Arlington's Great Meadows

On Monday local steward Holly Samuels reported a tree down across the path from Fottler to Brandon.

On Tuesday morning our rapid response stewards (Greg Shenstone and David Markun) came by and cleared the path.

Now it’s all clear again!

As of December 2024, iNaturalist has documented 674 species submitted by 122 observers at AGM, a mix of native, introduced, and invasive plants and animals. https://www.inaturalist.org/projects/arlington-s-great-meadows
Of these 674 species, few are considered rare. Finding a rare organism is exciting, but increasingly unlikely in our suburban area. Most of AGM’s residents are common.
So the question is, why?
Here is one of AGM’s most common inhabitants, the Common Drone Fly, Eristalis tenax, also common worldwide. What is the secret of its success?

Not what it seems

At first glance, it can be mistaken for a honeybee, which is no accident. It’s a Batesean mimic, a common strategy used by defenseless insects to avoid predation by resembling another insect, in this case the honeybee with its painful sting. https://en.wikipedia.org/wiki/Batesian_mimicry

A closer look at E. tenax reveals its fly identity — big eyes and tiny antenna, a thick “waist”, and two wings instead of four, as in bees and wasps. Males have larger eyes that meet at the top of the head, perhaps as an aid to finding females. E. tenax is a “flower fly”, also known as hover flies or syrphid flies. Like E. tenax, many are mimics of bees or wasps. They are also known for their exceptional flight, able to hover in mid air on nearly invisible wings, and disappear in a moment.

E. tenax is also common because its larva are not fussy. Larvae of of E. tenax live in polluted water such as drainage ditches, sewage, and other places where water is rich in organic matter the larva feeds on. Consequently, this medium has low oxygen content — a problem, because oxygen is required for the larva’s growth and survival. It has adapted by utilizing a siphon on its hind end (“rat-tail”) to access oxygen at the water’s surface, giving it its common name, “rat-tailed maggot”.
Complete metamorphosis
Like all flies and many other insects, E. tenax has multiple incarnations throughout its life, known as complete metamorphosis: egg, larva, pupa and adult. This radical yet ancient strategy for utilizing required resources at each stage of life is possible because of their relatively simple body plan and essential because of seasonal availabilities of resources and conditions for survival. For larvae, it’s all about eating — growing as quickly as possible. The pupal stage is a sort of super-charged puberty, completely rebuilding its body in its transition to adulthood. The adult fly is all about dispersal and reproduction, and its diet is mostly limited to nectar from flowers, made possible because of the more substantial diet of the maggot — as if in childhood, one ate only dinner, and in adulthood, only dessert.
The easy life
Like bees, the flower nectar-seeking habit of E. tenax and other flower flies makes them important pollinators. Bees need to collect pollen for their offspring and devote much of their time to raising their young and in the case of social bees, maintaining their colonies. Not so for the flower flies. Once the eggs are laid, the fly’s work is done.

References
https://www.inaturalist.org/projects/arlington-s-great-meadows
https://entnemdept.ufl.edu/creatures/livestock/rat-tailed_maggot.htm
https://en.wikipedia.org/wiki/Eristalis_tenax
https://www.syrphidae.com/name.php?id=0000ffcf-2e29-45b1-8da2-ed13eebbb650
https://repository.si.edu/bitstream/handle/10088/17482/521.pdf?sequence=1&isAllowed=y

Information provided by FoAGM volunteer Andrea Golden