Maine’s Department of Inland Fish & Wildlife (DIFW) recently completed an update of its Species of Special Concern list, and added three rare and unusual insects known as flower flies.
The state maintains a list of Species of Special Concern, which it defines as “any species of fish or wildlife that does not meet the criteria of an endangered or threatened species but is particularly vulnerable, and could easily become, an endangered, threatened, or extirpated species due to restricted distribution, low or declining numbers, specialized habitat needs or limits, or other factors.”
In its update this fall, the department proposed the addition of three insects: Holarctic Bristleside (Parasyrphus tarsatus), Hourglass Drone Fly (Eristalis brousii), and Slosson’s Pond Fly (Sericomyia slossonae). They belong to a group of bugs known as flower flies, also called hoverflies or Syrphid flies. They’re an underappreciated but fascinating group of critters, vital to the pollination of flowers around the world but experiencing a severe decline.
There are more than 6,000 known species around the world, and they fill critical ecological niches throughout their life cycles. As larvae, hoverflies are important predators. They prey upon plant-pests such as aphids, scale insects and thrips, and are therefore an important natural biological control for agriculture. As adults, flower flies switch their diets to pollen, and then become crucial pollinators for flowers across the globe. Studies have shown that hoverflies visit at least 72% of global food crops and more than 70% of animal-pollinated wildflowers.
Flower flies are also famous for their hovering, as their other common name, “hoverflies,” implies. Unlike hummingbirds, these flies don’t hover to eat (they simply land on the flower like a bee), but are believed to hover to inspect potential sites to lay eggs, spot food, and to impress mates. In the latter instance, male flower flies will hover in one spot above the ground – the longer and steadier it can hold its position, the better.
However, like many insects, flower flies are in decline. As part of his in-progress report detailing arthropod declines in Maine, entomologist and University of Maine professor emeritus Dr. Francis Drummond wrote that flower fly surveys:
“[S]howed decline in total abundance over the sampling period from 1882-2020, with the decline appearing to start in the 1970s. The number of species or species richness showed no evidence for decline from 1882-2020. When the most common species … were investigated, 6 species showed evidence of decline and 1 showed evidence of increase.”
It’s a dire picture. This fall, Maine Audubon delivered a comment in support of DIFW’s suggested updates to the Species of Special Concern list. We hope that the additional conservation status can help these insects get the recognition and protection they deserve.
As a final note, DIFW’s rulemaking also proposed to remove a damselfly (Citrine Forktail) due to its questionable residency status in Maine; and remove five birds, one bat, one beetle, and one bee from the Species of Special Concern List, an administrative decision after the agency uplisted those species to the Maine Endangered Species List in 2023.
