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Celebrating Our Unsung Pollinator Heroes

When it comes to pollination, bees tend to get all of the buzz. While they are crucial to pollinating many crops, it is important to note that bees aren’t the only pollinators working hard to provide the ecosystem services we rely on to support our food system. In fact, one out of every three bites of food we take is made possible by pollinators. In order to raise awareness for the unsung pollinator heroes all around us, Beyond Pesticides created the Polli-NATION Campaign, which highlights the important work of a relatively unknown pollinator each month. With it, we will raise public awareness about these pollinators, their contribution to plant health and productivity and the preservation of natural resources, and the threats they face in their daily lives, including toxic pesticides and habitat loss. Polli-NATION members include species like butterflies, wasps, flies, beetles, birds, bats, and more. By taking the time to read about our featured Polli-NATION pollinator, you will not only learn about the many diverse species we call pollinators, but also discover what you can do in your daily life to help ensure their survival.

May 2017: Mexican Long-Tongued Bat

Name

The Mexican long tongued bat, scientific name Choeronycteris mexicana, is a species of bat aptly named for its tongue, which has the remarkable ability to extend to nearly a body length. It is less-commonly referred to as the hog-nosed bat.

Range

The Mexican long-tongued bat’s range extends from the southwest of the United States through Mexico and into Central America, according to the International Union for Conservation of Nature (IUCN). In the United States, the bat is restricted to the far-south of California, Arizona, Nevada, New Mexico, and Texas. It is found in most areas of Mexico but is absent from the Yucatan peninsula and the gulf coast. Further south, the bat is also found in southern Guatemala and El Salvador in addition to northern Nicaragua. The Mexican long-tongued bat participates in seasonal migrations rather than hibernation. The Texas Parks and Wildlife Department admits that the study of the bat’s migratory patterns has been inadequate. However, it is known that the females establish maternity roosts in the southwest of the United States in late spring. They and their young depart for Mexico and Central America with the onset of cold weather in October and November. There is some evidence that a few individuals will remain in warmer northern areas over the winter.

Diet and Pollination

Mexican long-tongued bats feed primarily on the nectar and pollen of night-blooming flowers. Favorites include agave and cacti. They are also known to eat cactus fruit as well as insects found on flowers and fruit where they feed. Their preferences for agave and cactus makes them an important pollinator as they carry pollen from one plant to another. The United States Department of Agriculture Forest Service notes that bats primarily pollinate large flowers that produce strong fragrance and large volumes of nectar. Over three-hundred species of fruit-bearing plants depend on the Mexican long-tongued bat and other bat species for pollination.

Physiology

The Mexican long-tongued bat belongs to the group of phyllostomid or “leaf nosed” bats. These bats are characterized by a projection from the end of the nose that looks like a leaf. The Texas Parks and Wildlife Department advises that the Mexican long-tongued bat can be distinguished from other “leaf nosed” bats by their short ears, narrow snout, and presence of a small tail. The Smithsonia Museum of Natural History notes that the nose leaf may help direct the bat’s echolocation signals. The National Science Research Library at Texas Tech University describes the Mexican long-tongued bat as medium sized – between three and four inches in length and weighing less than a tenth of a pound – with sooty-gray to brown coloration. Their extendable, long, tapering, brush-tipped tongues allow them to access nectar from deep within a great variety of night-blooming flowers while hovering.

Ecological Role

The Mexican long-tongued bat plays a multifaceted ecological role as predator, prey, and pollinator. Their diet largely consists of agave nectar and they play a major role in the pollination of non-cultivated agave. While nectar and pollen are their primary food source, they also prey on any insects who are present when they are feeding at a flower. In addition to their role in pollination, the bats also contribute to the survival of cacti by dispersing their seeds. According to the food-web site, What Eats, bats play an ecological role as part of the diet of a number of predators. Predatory birds, like hawks and owls, in addition to snakes and predatory mammals are known to include bats among their prey.

The role of the Mexican long-tongued bat in pollination has been somewhat diminished by the expansion of agriculture in its range. According to a 2014 Wired article, cultivated agave is actively pruned to prevent flowering. These agave reproduce via proliferation of plantlets. The Mexican-long tongued bat and other bat species mentioned in the article do not play a primary role in producing commercial agave “nectar,” which is not floral nectar, but a synthetic syrup made from the sap of the agave plant. In fact, destruction of habitat to create commercial agave fields may actually be hurting the bat populations.

Threats to Existence

The International Union for Conservation of Nature’s Red List categorizes the Mexican long-tongued bat status as “near threatened.” This means that the species is not currently endangered or vulnerable but is close to qualifying for those designations and is expected to move to a threatened category in the near future. The IUCN cites its wide range across North and Central America as an encouraging point but also cites concerns regarding the species dependence on fragile agave populations which are subject to infringement by livestock grazing and the practice of prescribed fires.

In addition to danger relating to the availability of agave, the Mexican long-tongued bat is subject to the threat of loss of roosting sites. The caves which harbor these bats are increasingly being invaded by miners and caving tourists which render the caves inhospitable. The Texas Parks and Wildlife Department clarifies that the bats are very sensitive and, when disturbed, will abandon their roost.

A recent study in Taiwan connected the use of imidacloprid, a neonicotinoid pesticide, to diminished ability to echolocate among bats. They found that bats who fed on insects exposed to imidacloprid developed difficulty travelling on established paths and frequently became lost while hunting. The researcher noted “When toxic substances accumulate to a certain level, they damage the bats’ neurons and destroy their echolocation system.”

Threats to bat species are particularly concerning because of their slow rate of reproduction. Bat mothers only give birth to a single pup each year. This renders bat populations particularly vulnerable to factors that might disturb food sources or prevent successful migration during mating season.

How to Protect the Species

Mexican long-tongued bats live in a range of environments including scrub and saguaro desert, deciduous, pine, and oak forests, and canyons. Preservation of these habitats as well as food sources is imperative to protect the future of the Mexican long-tongued bat. Similarly, insisting on habitat preservation and personally fostering food sources for your local bats is necessary to protect your regions species. Even if the Mexican long-tongued bat’s range doesn’t reach your region, there are many other species of bats who act as beneficial pollinators. Consult these species profiles to determine which bats contribute to pollination in your area.

It is also critical to avoid planting any seeds or flowers that have been coated in pollinator-toxic neonicotinoids. As established in the aforementioned study which linked imidacloprid to loss of ability to echolocate in bats, these chemicals can undermine your intent to provide habitat for wild pollinators. See Beyond Pesticides’ Pollinator Friendly Seed and Nursery Directory to source safe seeds. For more information, see the webpage on Managing Landscapes with Pollinators in Mind. You can also get active in your community to protect these pollinators by holding native planting days in the spring, and advocating for changes to community pesticide policies.

In addition to actively opposing destruction of habitat and food sources, you can provide personal support to local bat populations. One option is to install a bat house on your property. You can build your bat house yourself or order one online to provide non-traditional habitat for your region’s species.

Further, Mexican long-tongued bats and other bat species have been known to visit hummingbird feeders. If you do host a number of local species at your hummingbird feeder, refer to this recipe, endorsed by the Smithsonian’s National Zoo, to ensure the health of hummingbirds and bats alike. Make sure to use organic sugar to avoid exposing visitors to unnecessary pesticides. The Texas Parks and Wildlife Department supports the use of feeders to support bats which arrive too early in spring or which remain through the winter. However, they also note that sugar water, while helpful sustenance, will not support long-term survival of bats because it lacks important nutrients.

It is important to educate others to dispel the myths surrounding bats in your community. Bats are an important part of local ecosystems and play a large role in pollination and control of insect populations. There are only three species of bats feeding primarily on blood. These species are not found in the United States but have created a widespread fear around the larger 1,200 species order. Another myth is that bats are a common carrier of rabies. Bats, like all mammals, are capable of carrying rabies. However, infection is not widespread and the odds of a bat exposing you to rabies are very low. Know that individual bats who are active during daylight hours and those who are not disturbed when approached by humans are more likely to be infected. Remember, bats are wild animals and should only be handled by trained professionals. The organization Bat Conservation International has more information on bat myths here.

Citations

Chen, Chi-chung and Elizabeth Hsu, Research finds pesticide impairs echolocation ability in bats http://focustaiwan.tw/news/asoc/201701110013.aspx

Godínez-Alvarez, H., Valiente-Banuet, A. and Rojas-Martínez, A., 2002. The role of seed dispersers in the population dynamics of the columnar cactus Neobuxbaumia tetetzo. Ecology, 83(9), pp.2617-2629.International Union for Conservation of Nature, Redlist of Threatened Species: Choeronycteris mexicana   http://www.iucnredlist.org/details/4776/0

Pearson, Gwen, Tequila, Booze, and Bats https://www.wired.com/2014/06/tequila-booze-and-bats/

Smithsonian National Museum of Natural History, North American Mammals: Choeronycteris mexicana https://naturalhistory.si.edu/mna/image_info.cfm?species_id=43

Texas Parks and Wildlife Department, Mexican Long-tongued Bat http://tpwd.texas.gov/huntwild/wild/species/mexlong/

Texas Tech University, National Science Research Library, Mexican Long-tongued Bat http://www.nsrl.ttu.edu/tmot1/choemexi.htm

USDA Forest Service, Bat Pollination https://www.fs.fed.us/wildflowers/pollinators/animals/bats.shtml

What Eats, What Eats a Bat? http://www.whateats.com/what-eats-a-bat

Winter, Y. and von Helversen, O., 2003. Operational tongue length in phyllostomid nectar-feeding bats. Journal of mammalogy, 84(3), pp.886-896.

April 2017: Tumbling Flower Beetle

Name

Tumbling flower beetle is the common name for Mordellidae, a family of beetles comprising over 1,500 species, 200 of which are found in North America according to the Field Guide to Beetles of California. Their common name is derived from the movement pattern they exhibit when disturbed. The beetles use their large rear legs to kick, jump, and tumble in an erratic pattern to the confusion of predators and the amusement of human observers.

Range

The differentiation in this large family lends itself to near ubiquity. According to the Encyclopedia of Life, the tumbling flower beetle can be found on every continent except Antarctica. Texas A&M notes the individual species are not overly adapted to specific environments and a number of species frequently overlap within a single ecosystem.

Diet and Pollination

Beetles are frequently overlooked in the world of pollinators. According to the United States Department of Agriculture’s Forest Service, the tumbling flower beetle’s ancestors were some of the earliest insects to utilize flowers for food and habitat. In doing so, these ancient pollinators began an important collaboration between flowers and beetles which continues today. Mature tumbling flower beetles feed on the pollen of flowering plants. They pollinate as they feed, transporting pollen on their body from a previous flower to successive locations. Idaho State University notes that beetles play a more important role in the pollination of tropical regions than in temperate ones. Even so, there are approximately 50 native plant species in the United States and Canada which depend upon beetle pollination.

Physiology

The large number of tumbling flower beetle species are unified by general appearance. Texas A&M describes the beetles as small, narrow, and wedge-shaped at just 1/4 inches long. Most species are black or dark brown but some are yellow or reddish and can exhibit thick bands, small stripes, and even spots. Their bodies are covered in fine hair which, in some species, becomes iridescent in sunlight. The tumbling action, for which the beetle is named, is caused by their jumping technique. They are equipped with large and strong rear legs for powerful jumping. Interestingly, they use a single leg of the rear pair to apply an uneven force to the ground and cause their body to both roll and somersault. According to the Encyclopedia of Life, the beetle uses this action to reposition its body for takeoff and may make successive tumbles until the correct position is achieved. Tumbling flower beetles are strong fliers but also frequently elect to tumble to the safety of ground from their perch.

Ecological Role

The guidebook Attracting Native Pollinators notes that the life cycle of the tumbling flower beetle revolves around the flowers it pollinates. With the onset of spring, the beetles reach maturity and begin to mate. In most species, the females lay their eggs in the stalk and stems of those same flowers. There, the larvae will develop and feed until the following spring when they emerge and repeat the process.  Some other species prefer to lay their eggs in decomposing wood where larvae play a limited role in recycling dead plant material. The tumbling flower beetle also plays an important ecological role as prey to other creatures. The article Bird predation and the host-plant shift by the goldenrod stem galler notes that downy woodpeckers and other birds eat tumbling flower beetle larvae. Adults are hypothesized to be prey to birds as well in A mordellid-meloid mimicry. Further, crab spiders are known ambush predators of a wide range of insects which frequent flowers.

Threats to Existence

The tumbling flower beetle family of species is currently thriving and is not listed on the International Union for Conservation’s Red List of Threatened Species. This means there is no evidence that the existence of the family is currently at risk. Even though the tumbling flower beetle is not in immediate danger, conservation efforts to protect its future should not be ignored. According to Kansas State University and Texas A&M, the tumbling flower beetle does little to no damage to crops and is not considered an agricultural pest. However, its larvae do bore into stalks and may be grouped with other stalk-boring insects which collectively cause crop damage. The crops which house the tumbling flower beetle larvae may be treated with pesticides targeting more destructive insects to the detriment of tumbling flower beetle populations. However, the stem-boring habit of the larvae generally protects them from non-systemic pesticides.

How to Protect the Species

There are steps that can be taken to ensure that the tumbling flower beetle continues to thrive. Noted favorite plants in the Field Guide to Beetles of California are buckwheat and sunflowers. Texas A&M suggests the composite and umbelliferous flower families are also popular. Planting these preferred varieties of flowers is a great way you can support the tumbling flower beetle. They will use the plants’ stems to host their larvae and their pollen as a food source. The females will insert their eggs beneath the skin on stems. According to Kansas State University, as many as 40 larvae may be distributed throughout the plant in this way. Avoiding the use of pesticides is paramount in protecting beneficial pollinators in your area. Tumbling flower beetles can be exposed by interacting with plants, soil, or air that have been subjected to pesticides. You should be aware of the chemicals used in your gardening solutions and avoid buying products that that contain neonicotinoids, a class of chemicals linked to pollinator declines. For more information on the impact pesticides have on non-target organisms read Beyond Pesticides’ report on Bees, Birds, and Beneficials, which can be found here. Switching to organic means of pest control around your home and garden is the best way to protect the health of pollinator populations in your community. For more information on how you can get involved in pollinator conservation throughout the nation, see Beyond Pesticides BEE Protective webpage.

Citations:

Deyrup, M. and Eisner, T., 1987. A mordellid-meloid mimicry. Psyche (Cambridge, Massachusetts), 94(3), pp.215-218. http://biostor.org/reference/175288

Encyclopedia Britannica https://www.britannica.com/animal/tumbling-flower-beetle

Encyclopedia of Life http://eol.org/pages/399/overview

Evans, Arthur V. and Hogue, James M., Field Guide to Beetles of California. Click here to see citation.

Idaho State University http://www2.isu.edu/~fultjess/Pollinators/Beetles.html

Kansas State University, Department of Entomology http://entomology.k-state.edu/extension/insect-information/crop-pests/sunflowers/tumbling-flower-beetle.html

Morse, D.H., 1986. Predatory risk to insects foraging at flowers. Oikos, pp.223-228. https://www.jstor.org/stable/3548353?seq=1#page_scan_tab_contents

Poff, A.C., Haynes, K.J., Szymanski, M., Back, D., Williams, M.A. and Cronin, J.T., 2002. Bird predation and the host-plant shift by the goldenrod stem galler. The Canadian Entomologist, 134(02), pp.215-227 http://www.jcronin.biology.lsu.edu/publications/canent02.PDF

Shepherd, Matthew and Vaughn, Mace, Attracting Native Pollinators. Click here to see citation.

Texas A&M Agrilife Extension http://texasinsects.tamu.edu/bimg162.html

USDA Forest Service https://www.fs.fed.us/wildflowers/pollinators/animals/beetles.shtml

March 2017: Fig Wasp

Name

The Fig wasp is a highly evolved pollinator crucial to the life cycle of the fig tree.  Part of the chalcidoid family, the Fig wasp is a member of the agaonidae sub family, which consists of both mutualistic pollinating, and parasitic, non-pollinating, fig wasps. 

Fig wasps have a mutually beneficially relationship with fig trees, as both the tree and the wasp rely on each other for reproduction.  According to the Encyclopedia Britannica, there are about 900 species of pollinating fig wasps that are responsible for pollinating 900 different fig tree species. The relationship between fig trees and fig wasps is so evolved that each type of fig wasp pollinates only one specific type of fig tree, creating a beautiful and interdependent evolutionary partnership.

Range

The range of the fig wasp is dependent on the range of fig trees, which, according to the Encyclopedia of Life, are mainly found in the tropical and subtropical areas of the southern hemisphere. The most widely known fig tree, the common fig tree, or Ficus carica, is native to southwest Asia and the Mediterranean, and range anywhere from Afghanistan to Portugal.  The strong demand and high commercial value of the fig fruit has led to the naturalization of the common fig tree in additional parts of the world that have the requisite mild and semi-arid climate required for the species to grow.  California, Oregon, Texas, Utah and Washington all commercially produce the common fig tree.

Western consumers predominately eat figs from the common fig tree. This is due largely to the fact that this variety does not require pollination to the same extent as other fig species, making them easy to grow at home or in climates without naturally occurring fig wasp populations. However, there are two species of fig wasps that have been introduced in North America, which are typically used to pollinate the commercially valuable Smyrna fig.

Diet, Pollination, and Life Cycle

The fig wasp, as mentioned earlier, exclusively coexists with fig trees, which makes the fig fruit their primary source of nutrition.  In order to understand the diet and method of pollination of the fig wasp it is important to understand their life cycle, which is heavily intertwined with the fig fruit. Fig wasps can be separated into two different groups, pollinating and non-pollinating, each of which plays an important role in the life cycle of a fig. Pollinating wasps provide a mutually beneficial service to the trees in the form of pollination, while non-pollinating wasps use the plant as a source of food, and often act as a parasites to either the fig plant or the pollinating wasps. 

The first stage in the fig wasp’s life cycle occurs when a female fig wasp first enters an unripe fig fruit through a small opening known as the ostiole, and travels to the synconium, or inner part of the fig fruit, which contains both male and female flowers. Once inside, she will lay her eggs in the shorter flower structures. The longer flower structures remain unfertilized and eventually develop into the seeds you see inside of a fig. While laying her eggs, the female fig wasp inadvertently pollinates the female flowers found inside the fig fruit by transferring traces of pollen particles from the fig fruit in which she originally hatched. Once their eggs are laid, female fig wasps die within the fig. 

As the fig fruit and the eggs mature, male wasps hatch and emerge from their eggs, known as galls, traveling within the fruit towards the synconium in search of females to fertilize. After doing his part to fertilize the female, a male fig wasp will begin digging escape tunnels for the females once they hatch, though he will never get to benefit from them himself, as males die within the fig fruit during this process. Because they never leave the fruit in which they were born, male fig wasps do not have wings.

As all of this is happening, the male flowers are maturing and creating pollen for the new batch of female fig wasps to transfer to the next fig fruit. Once the female hatches she makes her way through one of the escape tunnels dug by the males, picking up pollen from the male flowers in the process. With pollen now in tow via her body, the female emerges in search of a new fruit to lay her eggs in, pollinating another fig in the process and starting the cycle all over again. It is through this process that the highly specialized and enclosed flowers within the figs are pollinated, further demonstrating the interdependence between the life cycle of the fig wasp and the fig tree.

Physiology

Fig wasps are much smaller than common wasp species and more closely resemble a fruit fly, with body lengths reaching only 1-2 mm in length.  With around 900 different species of fig wasps there are physical differences from one species to the next due to coevolution with their host fig tree species.  Despite this highly evolved individuality, fig wasps do share some general some characteristics across the species.

Female fig wasps are larger in size than male fig wasps and, as mentioned above, females have wings while males do not, as they do not leave the fig within their life cycle.  However, because one of their primary roles is to create tunnels for female wasps to exit the fig, male fig wasps have strong, specialized mandibles built to chew through the fig’s tough outer flesh.  Females, on the other hand, are equipped with wings to travel to another fig tree or fig fruit to lay eggs. 

According to the Encyclopedia of Life the female fig wasp’s body has evolved over time to fit into the ostiole of the fig.  There are special appendages on her head that help her body inch through the tight opening on the fig.  Additionally, some species of female fig wasps have evolved to have an extremely long ovipositor, the body part responsible for laying eggs.  This allows the female to lay her eggs from the outside of the fig without entering and trapping herself within the fruit.  Fig wasps have very short life spans, living only between 1-2 days once hatched from their eggs.

Ecological Role

The fig wasp may seem like a menial pollinator given that they only pollinate one type of plant, but that is far from the case!  The fig wasp is an integral species, as the fig tree has been identified as a keystone species in tropical rainforests where they help maintain the population and diversity of a variety of species.  The Encyclopedia of Life defines a keystone species as “a species within the ecosystem that exerts a major influence on the composition and dynamics of the ecosystem of which it lives.”  This means that the fig tree is a species that has a disproportionally large effect on its environment, relative to its abundance within the ecosystem.  

Many species rely on the fig fruit and its leaves as their main source of nutrients.  The Encyclopedia of Life lists the fig as a key resource for many fruit eating animals including fruit bats, several species of monkeys, and a plethora of birds.  Insects like caterpillars, moths and beetles all feed on the leaves of the fig tree. In fact, over 1,200 different species of birds and mammals have been recorded to eat fig fruits.

Threats to Existence and How to Protect Species

Currently the fig wasp and the fig tree are not in immediate danger, however some scientists are concerned that climate change and global warming could have a negative impact on fig wasp populations.  In a study done in Singapore in 2013, researchers studying fig wasps discovered that fig wasp survivability drastically reduced in climates that were warmer than their desired habitats.  More extreme climates could threaten the productivity of fig wasps, possibly causing a decline in fig tree populations.  They hypothesize that as climate change continues to intensify, the insects will alter their behavior in order to adapt to warmer climates. However, if the changes in temperature take place too quickly for these adaptations to occur, it could conceivably threaten the existence of the fig wasp.

Tropical rainforest deforestation also poses a threat to fig wasps.  As human development and agricultural activity continues to expand, forests around the world are being cleared at alarming rates, especially in developing countries where most of the world’s tropical rainforests are located.  Fig trees and their companion pollinators are incredibly important to rainforest ecosystems, as they provide a popular source of food and attract seed dispersing animals.

There are a few things that can be done within your community to protect and foster fig wasps and fig tree populations.  For starters, if you live in an area with an appropriate climate, consider planting a fig tree in your yard, garden, or community! The next vital step in protecting fig wasps and fig trees is to avoid the use of pesticides in your community.  You should be aware of the chemicals used in your gardening solutions and avoid buying products that that contain neonicotinoids, a class of chemicals linked to pollinator declines. Neonicotinoids are systemic by nature, and if sprayed near a fig tree could be transported through the roots into the flower of the plant, threatening the fig wasps who live inside. For more information on the impact pesticides have on non-target organisms read Beyond Pesticides’ report on Bees, Birds, and Beneficials, which can be found here.

Switching to organic means to control pests around your home and garden is the best way to protect the health of pollinator populations in your community.  For more information on how you can get involved in pollinator conservation throughout the nation, see Beyond Pesticides BEE Protective webpage.

Citations

Cook, James M. and West, Stuart A. Figs and Fig Wasps. Current Biology Vol 15, No 24. http://www.zoo.ox.ac.uk/group/west/pdf/Cook&West_05.pdf

Encyclopedia Britannica https://www.britannica.com/animal/fig-wasp

Encyclopedia of Life (Fig Wasp) http://eol.org/pages/736/details

Encyclopedia of Life (Fig Tree) http://eol.org/pages/60627/details

Jevanandam N, Goh AGR, Corlett RT. 2013 Climate warming and the potential extinction of fig wasps, the obligate pollinators of figs. Biol Lett 9: 20130041. http://dx.doi.org/10.1098/rsbl.2013.0041

February 2017: Ruby Throated Hummingbird

Name

A quick flash of red and green will likely be the most you’ll see of the Ruby Throated Hummingbird.  They are one of nature’s most nimble and agile birds, hovering over flowers for just a second or less before moving on to the next.  The Ruby Throated Hummingbird, or Archilochus colubris, is the most abundant species of hummingbird specific to the eastern half of North America.  They are named after the coloration of ruby red feathers around their throat.

Range

The Ruby Throated Hummingbird is the most populous hummingbird found east of the Mississippi.  They enjoy mild habitats such as pine and deciduous forests, and can also be found zipping around urban and suburban gardens and orchards.  Ruby Throated Hummingbirds “winter,” meaning they migrate to warmer parts of the globe during the colder winter months.  They typically spend that time in parts of Central America and southern Mexico, but have been known to travel as far south as Costa Rica and the West Indies, according to Animal Diversity Web.  They will often migrate without stopping, traveling distances as great as 1600 km in one trip.

According to the Encyclopedia of Life, the hummingbird’s mating grounds are typically east of the 100th meridian in the United States and parts of southern Canada.  Their ability to inhabit such a diverse range of habitats make them an important pollinator to many ecosystems across eastern North America.

Diet and Pollination

Nectar from flowering plants comprises the majority of the Ruby Throated Hummingbird’s diet, but fat and protein are supplied by small insects, including mosquitoes, spiders, gnats, fruit flies, and small species of bees. They have also been observed eating tree sap, and their northern limit is probably determined by the availability of sap provided by the drilling of sapsuckers.

According to the Encyclopedia of Life, Ruby Throated Hummingbirds have adapted to be able to see the UV spectrum of light in addition to the visible light spectrum, which helps them locate and differentiate between a variety flowers. Their favorites include:  Red Buckeye, Jewel Weed, Trumpet Creeper, Red Morning Glory, Coral Honeysuckle and the Cardinal Flower, just to name a few.

Physiology

Most hummingbirds are small statured compared to their other avian counterparts, and the Ruby Throated Hummingbird is no exception. Ranging in length from 7 to 9 cm and weighing only a few grams, the bird can easily fit in the palm of your hand.  Their incredible flying abilities are attributed to their lightweight and stream line bodies. Spectacular as those abilities are, however, they can be taxing on the bird and require a lot of energy. Because of this, the Ruby Throated Hummingbird will consume twice their body weight in food each day.

Ruby Throated Hummingbird’s coloration is striking, featuring beautiful shades of green, white and red. Males can be distinguished from females by their tail feathers, as males have a forked feather configuration while females boast a square feather configuration with white tips. Males additionally have the characteristic red, ruby throat while females will have a duller, grayish-red colored throat. Females are larger than their male counterparts.

Ruby Throated Hummingbirds are migratory birds, returning to their breeding grounds in eastern North America each spring. Males generally return to the breeding grounds ahead of females to stake out their territory for mating. Once a female enters a male’s territory, the male bird will court the female with a dive display meant to impress the female. As part of this display, the male will do a variety of loops and acrobatic flying maneuvers, beating its wings up to 200 times per second. After successful breeding, the female constructs a nest for her eggs out of bud scales and lichen, held together with spider’s silk and lined with plant down. There the female will lay one to three eggs, which are incubated for 10-14 days before they hatch, a cycle that is repeated two or three times per breeding season. The average lifespan of the Ruby Throated Hummingbird is about nine years.

Ecological Role

Ruby Throated Hummingbirds live on a diet of nectar from a variety of flowering plants and, as previously stated, consume up to twice their bodyweight in nectar each day. This requires constant foraging for sources of nectar and the birds spend most of their day flying flower to flower in search of this food source. They are equipped with a long, skinny modified beak that allows them to access nectar, as well as a long tongue that can further be extended into the flower.

While foraging for nectar the hummingbird simultaneously contaminates itself with pollen particles from the flower. The pollen sticks to the birds’ feathers and beak, allowing the bird to transport it to the next flower it visits. Once that pollen comes in to contact with a new flower, the plant is inadvertently cross-pollinated, allowing the plant to reproduce. The abundance of Ruby Throated Hummingbirds make them an integral pollinator to ecosystems across the eastern United States and parts of Canada. Partners for flight, an organization that tracks land birds for conservation purposes, estimates the Ruby Throated Hummingbird population in North America and Canada is as great as 34 million.

Threats to Existence

The Ruby Throated Hummingbird is currently a thriving species, labeled as a species with “Least Concern” by the International Union for Conservation. This simply means their existence is not currently at risk. The United States Geological Service Patuxent Wildlife research center, which has been tracking land bird species since the 1960’s, has found that Ruby Throated Hummingbird populations have been on the rise since their studies began. Even though the species is not currently at risk, however, conservation efforts to protect the birds’ future success should not be ignored. Destruction of natural habitat is a primary risk that can affect the hummingbird’s ability to prepare for migration, as well as diminish the bird’s breeding grounds and disrupt its reproductive success. The bird’s exposure to systemic pesticides that move through a plant’s vascular and is expressed in nectar is of particular concern.

How to Protect the Species

There are steps that can be taken to protect Ruby Throated Hummingbirds, one of the most popular being to install a hummingbird feeder in your yard or garden. Simple actions, like placing your hummingbird feeders away from windows to prevent collisions, or situating feeders in places where cats and other neighborhood predators will have a difficult time reaching the birds, are important ways to help hummingbirds thrive.  Routine cleaning of hummingbird feeders is also important, as rancid feeders can be detrimental to hummingbird health. Supplying your hummingbird feeder with the right nectar solution is also important. You can find a trusted nectar recipe recommended by the Smithsonian National Zoo by clicking here!  Be sure to use organic sugar in your mix, as it will ensure that your nectar solution is free of pesticides and additives.

Planting the aforementioned flowers preferred by the Ruby Throated Hummingbird is another way you can preserve hummingbird populations, as they require nectar for survival.  Avoiding the use of pesticides is also paramount in protecting bird populations in your backyard.  Birds can be exposed to pesticides indirectly through the ingestion of insects that have been in contact with pesticides, or directly by interacting with plants that have been subjected to pesticides. You should be aware of the chemicals used in your gardening solutions and avoid buying products that that contain neonicotinoids, a class of chemicals linked to pollinator declines. For more information on the impact pesticides have on non-target organisms read Beyond Pesticides’ report on Bees, Birds, and Beneficials, which can be found here.

Switching to organic means to control pests around your home and garden is the best way to protect the health of bird populations in your community.  For more information on how you can get involved in pollinator conservation throughout the nation, see Beyond Pesticides BEE Protective webpage.

Citations

Animal Diversity Web, Encyclopedia of Life, The Birder's Handbook by Paul Ehrlich, David Dobkin, and Darryl Wheye (1988).

January 2017: Bee Flies

Name

Over 5,000 species of Bombyliidae (Bee Flies), a large family within the order Diptera, can be found across the globe. While few of these species have been researched in great depth, they all have similarities that tie them to their classification. The vast majority of Bee Fly species have larvae that are parasitoids, and all adults feed on a diet of pollen and/or nectar, making them important pollinators.

Photo by AJC1 on Flikr

Range

Bee Flies have been discovered on every continent but Antarctica. The most diverse group of species can be found in semi-arid and arid (desert) environments such as western North America, southern parts of South America, along the equatorial lines of Africa, and the mid latitudes of Eurasia.

Diet and Pollination

Most Bee Flies in their larval stage are parasitoids to the larvae of other soil-inhabiting insects. As opposed to parasites, which usually live off their host, but do not always cause death, parasitoids like the Bee Fly always kill their host. According to the World Catalog of Bee Flies, larvae of some Bombyliidae species prey on major agricultural pests, such as locusts, grasshoppers, armyworms, slugs, and caterpillars. However, select species have been found to be parasitoids of other pollinators like solitary bumblebees. And a small number species of Bee Fly larvae simply prey on insect eggs.

Most adult Bee Flies, once fully mature, feed on nectar from a variety of native flowering plants. Females are required to consume pollen in order to provide the protein and nourishment necessary for the development of eggs and reproduction. Bee Flies are thought to be responsible for what are called “pollination syndromes,” meaning many native flowering plants coevolved and adapted with Bee Flies.

Physiology

Adult Bee Flies are adapted for a pollen and nectar diet, and their physiology shows it. They have small bodies which range in length from 1mm to 2.5cm, depending on the species. Their wingspan can be as small as 1.5mm, though larger species can have a span of more than 60mm.  Many species utilize biomimicry, in terms of their coloration, often resembling bees (hence their common name as the Bee Fly) or wasps. This offers them protection, as their predators assume that they have the temperament of a more aggressive species. Nonetheless, some species simply have a solid coloration of grey or rusted brown. Bee Flies’ wings appear swept back when at rest, and their legs are generally long and skinny compared to their body, with bristles at the ends. Many Bee flies are equipped with a very long proboscis (tubes that enable them to lap up nectar) that allows them to collect nectar from flowers with long narrow floral tubes. The Bee Flies’ proboscis is fixed, and cannot be retracted, giving it a tusk-like resemblance.  

Ecological Role

Bee flies play an important ecological role as pollinators, particularly for flowering desert plants in the U.S. Southwest. Although the Bombyliidae family is understudied, the World Catalog of Bee Flies notes that because many flowering plants require Bee Fly pollination in order to propagate, some endangered plant species are likely reliant on the conservation of certain bee fly species. In addition to providing valuable pollinator services as adults, as noted earlier, Bee Fly larvae can play an important role in pest control. In addition to controlling agricultural pests like slugs and locusts, some species prey on the tste fly, which are infamous for their ability to transmit human diseases like trypanosomiasis, or sleeping sickness.

Threats to Existence

A literature review by the Bureau of Land Management (BLM) notes, “At any single locality a population of bee flies may be considered to be endangered, but throughout the desert areas they may not appear to be so because of their apparent wide distribution.” Because their interaction between specific flowers and certain Bee Fly species is so closely intertwined, habitat loss represents a significant threat to the Bombyliidae family. BLM’s literature review provides an example of the importance of maintaining habitat in the Algodones Dunes near Imperial County, CA. Areas open to recreational vehicles like ATVs resulted in the loss of a majority of flowering plants. While Bee Fly numbers in these areas became locally extinct, areas adjacent to the recreational area maintained their population numbers.

Pesticides, particularly persistent, systemic neonicotonoid insecticides, also represent a serious threat to many Bombyliidae species. Because many species feed on agricultural pests, they are more likely to be exposed to pesticides in these areas. Although the impacts of neonicotinoids and other pesticides on wild pollinator species are understudied when compared to investigations on honey bees, research that has been performed is cause for concern.

How to Protect the Species

There are a few simple ways to protect Bee Fly populations. Providing habitat by planting native flowers is an important first step for Bombyliidae conservation. Providing native habitat is especially important for individuals in arid or semi-arid regions of the U.S. Southwest, and these flowers are relatively easy to maintain as they do not require a lot of water and there is plentiful sun.

It is also critical to avoid planting any seeds or flowers that may be coated in pollinator-toxic neonicotinoids, as these chemicals can undermine your intent to provide forage and habitat for wild pollinators. See Beyond Pesticides’ Pollinator Friendly Seed and Nursery Directory as a starting place. And for more information, see the webpage on Managing Landscapes with Pollinators in Mind. You can also get active in your community to protect these pollinators by holding native planting days in the spring, and advocating for changes to community pesticide policies. Lastly, by buying organic, you can support an agricultural system that eschews the use of toxic pesticides like neonicotinoids that harm native pollinators.

For more information on how you can get involved in pollinator conservation throughout the nation, see Beyond Pesticides BEE Protective webpage.

Citation/Additional Resources

Evenhuis, N.L. 2015. World catalog of bee flies (Diptera: Bombyliidae) web site. http://hbs.bishopmuseum.org/bombcat/

Hall, J. 1979. Review of literature and museums for groups of the bombyliidae, bee flies, and outline of the districution fo rate and potentially endangered species in the California Desert Conservation Area. http://www.biodiversitylibrary.org/item/121097#page/1/mode/1up

Yeates, D and Lambkin, C. 2004. Tree of Life web project. http://www.tolweb.org/Bombyliidae