By Sam Burbach, Education & Programming Coordinator – 06/25/2020
While bees carry out the most pollination services and butterflies and moths are some of the most beautiful pollinators, there are other insects that play an important role in pollination. Let’s look at two of the largest groups of insect pollinators outside of bees, butterflies, and moths: beetles and flies!
Beetles have been pollinating flowers since prehistoric times and are some of the first insect pollinators, dating back to the Mesozoic Era about 200 million years ago. When angiosperms (flowering plants) evolved about 125 million years ago, beetles were very important pollinators because bees and butterflies had not evolved yet. Beetles visit flowers to feed on nectar, pollen and sometimes the flower itself, which has led to beetle-pollinated flowers evolving to include some very important traits, such as excess pollen production and thicker petals and flower parts.
Beetles prefer flowers with open or cup-shaped flowers, and exposed pollen. Flowers that attract beetles for pollination often have a strong fragrance that can be sweet, spicy, musty, or even fermented. It is most common to have plants that rely on beetle pollination in tropical areas, but in our area plants such as magnolias, tulip trees, and water lilies also rely on beetle pollination.
Beetles have been pollinating magnolia blossoms for millions of years. (Photograph by Adrian Scottow, Flickr Creative Commons)
Red-necked false blister beetle, Asclera ruficollis. (Photograph by Beatriz Moisset)
Flies are often thought of as pests but many of them are beneficial insects and carry out important pollination services. Flies might visit flowers to feed on nectar or pollen, to lay eggs, or even to feed on smaller insects visiting the flower. Flies are attracted to more putrid fragrances, such as rotting meat, dung, humus/decomposing plant matter, and blood. Flowers that rely on flies for pollination have adapted to produce these odors and sometimes even share the same color as meat, such as red, maroon or purple-brown.
The Pawpaw tree is an example of a plant that relies of flies and beetles for pollination. The flowers have a faint odor which resembles rotting meat and are a maroon to purple-brown color to mimic the appearance of meat. Flies and carrion beetles are attracted to these flowers since their diet includes dead and decaying animals.
A group of flies that are highly hated are biting midges. These tiny insects have a painful bite and can easily spread disease making many people wish their existence would just go away; and yet, many people couldn’t exist (figuratively, that is) without at least one genus of midges. The tiny, pinhead sized flies from the Forcipomyia genus of the midge family are believed to be the only creatures to pollinate the flowers of the beloved Theobroma cacao, or cacao tree. The flowers of the cacao tree are rather intricate and require a very small pollinator to initiate the development of some of our favorite seeds. Without these chocolate midges we would no longer have chocolate, so the next time you enjoy some chocolate say a little thank you to midges!
A gall midge pollinates cacao, the plant that provides the main ingredient for chocolate. The most famous cacao pollinator is the chocolate midge. (Photograph by Mark Moffett, National Geographic Creative)
House fly pollinating pawpaw flower. (Photograph by Peterson Pawpaws)