Much of the attention given to insect pollinators focuses on bees and butterflies with a passing interest given to moths and perhaps wasps. Flies and beetles are sometimes depicted when a photo to promote bee conservation is mistakenly a syrphid, bee fly or, on the rare occasion, a flower longhorn beetle. The diverse array of flower-visiting flies and beetles are overlooked. True bugs (e.g., stink bugs, plant bugs, and assassin bugs) are never mentioned.
Documenting Flower-Visiting Insects
In 2018, I developed a long-term research project using photography surveys to document likely pollinators and other flower visitors (also known as anthophiles) in permanently protected nature preserves in West Central Illinois. The overarching goal was and is to collect data to determine potential impacts on pollinator diversity and abundance due to management and/or other landscape-scale changes. The study is also meant to address the “we don’t know enough” excuse that has delayed progress in insect conservation.
The study initially comprised six sites visited four times each year (during different parts of the growing season), for 60 to 90 minutes each visit. I planned to visit six new sites each year for a total of 30 sites in five years and then to repeat the process every five years. For the research project, I recorded all bees, butterflies and skippers regardless of flower visitations. I also recorded all other insects that appeared to be foraging on pollen or nectar or that were transporting pollen on their body: That is, those insects that might be contributing to pollination. I photographed as many flower-visiting insects as possible and manually documented the others, also noting which flower species each insect was visiting. In my sixth year (the first year of repeated surveys) I switched over to voice-recording to allow myself more time to photograph insects and to better document each insect-flower interaction rather than just the plant visited by each type of insect.
Creating an Archive
Most of my photographs have been uploaded to I-Naturalist.org for identification or confirmation assistance, and to provide permanent documentation of the different insects at each preserve. Additionally, a few dozen bees were collected to obtain species identification in the lab, as many bees cannot be identified to the species level with just a photograph. Photographs were identified to the lowest taxa level possible: species, subgenus, genus, tribe, or family.
The purpose of selecting photography over lethal collection was based on my experience with butterfly surveys (I learned to do all my observations by sight and photo documentation) and lack of time and resources necessary to collect, process, and identify thousands of dead insects. For me, photographs were simply easier to archive and share. Image identification also aligns with my role as a Natural Preservation Specialist with the Illinois Nature Preserves Commission as my primary job duty is to preserve native diversity within high quality remnants and habitats supporting rare species or communities.
A Surprising Range of Insects Visit Flowers
With the increased interest in wild pollinators there has been some attention given to syrphid (flower) flies and bee flies as most members of these families feed on pollen and nectar. However, as part of my study, I observed many other types of flower-visiting flies worthy of attention. These include soldier flies, midges, male mosquitoes, crane flies, mydas flies, tachinid (bristle) flies, muscid flies, blow flies, dance flies, and thick-headed flies, to name a few.
Beetles also made up a large percentage of the individuals and taxa observed on flowers. Of the beetles, flower longhorns may be the best known as these beetles are relatively large and enjoyable to photograph. However, I also observed other less famous, often smaller beetles such as weevils, flower scarabs, carpet beetles, sap feeding beetles, fireflies, soldier beetles, foliage ground beetles, blister beetles, click beetles, and more.
When I started the project I did not expected to find true bugs. True bugs of the suborder Heteroptera are known to feed on plant juices or seeds. Some, such as assassin bugs, prey on other insects. However, true bugs have a much more varied diet than is generally known. Many, including some of the predatory assassin bugs, will sip on nectar or consume flower pollen.
Interestingly, in the process of conducting my surveys, I found many bugs showed a preference for a particular flower species, genus, or family. This was true not just of the small and large milkweed bugs—which are well known to have an association with Asclepius—but also stilt bugs, stink bugs, seed bugs, plant bugs, scentless plant bugs, lace bugs, and assassin bugs. I found that often the ties were so strong that if I examined certain plants, I was likely to find the associated bugs as well.
A Sampling of Insect-Flower Associations
Some of the best examples of strong insect-flower associations I observed were, 1) rattlesnake master stink bug, 2) mountain mint seed bug, 3) stilt bug on biennial gaura, 4) false milkweed bug on ox-eye false sunflower, and 5) large milkweed bug.
Other bugs showed a preference for a certain group of plants, but were not strictly attached to those plants. These included, 1) Piezogaster (leaf-footed bug nymph) on tick trefoils, 2) green stink bug nymph on orange jewelweed, 3) pink scentless plant bug on daisy fleabane, and, 4) twice-stabbed stink bug on obedient plant.
Finally, generalist bugs visited many different flower types with seemingly no preferences. These included, 1) brown stink bug, 2) ebony bug, 3) white-margined burrower bug, 4) tarnished plant bug, 5) Sinea (assassin bug), and 6) helmeted squash bug.
From my photography pollinator study, Heteroptera (true bugs) represented about seven percent of the flower-visiting insects. While they likely make only a small contribution to the transfer of pollen needed for plant reproduction, it is likely we do not yet fully understand the role and significance of true bugs and their associations with flowering plants.
Recommendations for Attracting Flower-Associated Insects to Your Landscape
If you are interested in attracting more bugs to your backyard plantings, the advice I have is the same as that for attracting other pollinator insects. Plant more native plants! Focus on the plants that historically belong in your area such as by checking to see which ones grow in nearby remnants. (I used to explore railroad corridors and roadsides to see what natives were present.) These plants are more likely to thrive in your yard are are more likely to be utilized by the native insects in your area.
My absolute favorite plants for my area are mountain mints (Pycnanthemum) and golden Alexanders (Zizea aurea). I am a big proponent of planting more native spring bloomers as the early emerging insects often lack food. This is especially true as our winters become warmer and our springs arrive earlier. Prairie ragwort (Packera), pussytoes (Antennaria), blue-eyed grass (Sisyrinchium), cream wild indigo (Baptisia bracteata), wild hyacinth (Camassia), spiderwort (Tradescantia), wild geranium (Gernaium maculatum), and sweet cicely (Osmorhiza) are all excellent attractants in my region.
Diversity is the key. I like to pack in as many types of plants as my area will support given soil type, moisture, slope, shade or sun, etc. If given the opportunity to do so, planting native reconstructions adjacent to remnant sites allows insects more room to expand outward from isolated parks and preserves. The more habitat available, the more the insects can cope with increasing threats from pesticides, urbanization, invasive species, and a changing climate.
I want to encourage everyone reading this to do what you can to plant native, learn to appreciate all native flower-visiting insects (even the bugs), and take photos and share them on I-Naturalist or through other web-based citizen science groups collecting data. There is not enough funding and expertise to learn what is needed to help protect insect diversity. These insects need our help.
—Angella Moorehouse
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Angella Moorehouse is the author of the book, Flower Bugs, A Guide to Flower-Associated True Bugs of the Midwest, published by Pollination Press. Flower Bugs is intended to spark a greater interest and appreciation for flower-visiting true bugs by showcasing the connections between native plants and their insect companions. Angella is a Natural Areas Preservation Specialist with the Illinois Nature Preserves Commission and works as a field representative. She prepares conservation easements to protect high quality natural areas and assists in the management and monitoring of these sites. She has been conducting photography surveys of flower-visiting insects on 30 protected preserves in West Central Illinois since 2018. Angella has published several Rapid Field Guides on wasps, bees, flies, and moths with the Field Museum. These Guides are available as free downloads at Field Guides. All images in this article are courtesy of Angella Moorehouse.