While at my parents’ recently, taking photos of dandelions for a previous post, I happened to notice a fly on one of the flowers. It was diving in and burying its head among the petals, I assume collecting nectar. It was a metallic green, small and hairy. I had seen many of these before; I believe they’re greenbottle flies, quite possibly Lucilia sericata, and are a very common species found across the continent.
I decided to see how many different types of flies I could turn up in a quick tour of the property. I’ll add a disclaimer here that these IDs are all tentative, and I may have them incorrect – flies, like many groups of insects, are a notoriously difficult bunch to ID well. They’re easy to tell apart from other insect groups because they only have one pair of wings (unlike bees, wasps, mantids, butterflies, dragonflies, etc, etc, which have two pairs). Flies evolved from a four-winged insect, but their second pair of wings is reduced to vestigial knobs that serve the purpose of stabilizing the insect while in flight (I’m not quite sure how this is accomplished, beyond that it’s a sort of gyroscope effect).
The greenbottles were common. Another common fly was this one, which I think is a flesh fly, perhaps Sarcophaga sp. The group name suggests a connection to animal flesh, and many species do lay their eggs in open wounds or in carrion. However, there are also many that will parasitize invertebrates of many sorts, or will lay their eggs in dung or manure. In the case of this genus, the females lay their eggs mostly in carrion. Blow flies are the first maggots to appear in a roadkill, with the Sarcophaga arriving later. However, the latter will lay live larvae, rather than eggs, to make up for that time difference.
There are 250 species of Sarcophaga in North America, which even though it sounds like a lot, is just a drop in the bucket compared to the total number of dipteran flies on the continent – about 17,000 species, more than the moths I’m attempting to learn, and utilizing a broader set of ecosystem resources – moths generally don’t have much to do with animals, while many flies, as we know, are common nuisances.
One of the things I love about this photo is you can see the sucker pads on the fly’s feet. These are what allow flies to walk along a wall or the ceiling, seeming to defy gravity.
This particular individual was grooming itself, and had its mouthparts exposed for cleaning. Most flies have some sort of sucker-like mouthpart that they use either for sponging up food (such as nectar), sort of in the manner a cat will lick up a bowl of milk, but some have a piercing mouthpart that they use to pierce and suck up their food, such as with biting flies like black flies. Mosquitoes, even though they don’t look it, are actually a type of fly as well.
Despite their reputation for spreading disease, most flies are fastidious groomers. There are some groups that inhabit unsanitary conditions and are attracted to manure, sweat, dead animals, and other things we tend to think of as dirty. However, the majority of flies don’t have much to do with such things, instead frequenting flowers or other food sources. If you watch a resting fly, chances are it will groom itself while it’s sitting there, running its legs over its wings, eyes, and other legs.
One of those flower-visiting flies is this bee fly, probably Bombylius major. They’re named bee flies not for their resemblence to bees (which they superficially do, particularly the bumblebees), but rather for their habit of parasitizing ground-nesting bees. This species is very widespread and relatively common. I watched it for some time visiting the forget-me-nots. It never strayed far from this patch, which was handy, because when I first spotted it I didn’t have my camera on me (I forget what I was doing now, but it was not related to photographing things), and it allowed me to run inside to grab it. It would hover in front of the flowers it was visiting, rather than landing on them to feed.
Many of the “true” flower flies, belonging to the group Syrphidae, are mimics of bees and wasps. This presumably affords them some measure of protection against creatures who would ordinarily view non-stinging flies as a food item. They’re also known in some regions as hover flies for their habit of hovering in front of flowers, but not all hovering flies are Syrphids, and not all Syrphids hover. The group are valuable pollinators of flowers, and the larvae of many species prey on aphids. This one, probably Helophilus fasciatus, I think is likely a male – the females have longer abdomens with an extra black band than the male, and a long black stripe between the eyes that the male lacks.
This fly looks albino, with its overall pink colouration and orangey-pink eyes, but I believe its actually a normally-pigmented member of the myzid fly group, in the genus Suillia. There are 100 species in this family in North America, eight in this genus, but the life cycles of most aren’t well-known. In those where they have been studied, larvae are found in a variety of habitats where animal droppings can be found, such as in burrows, bird nests, or bat caves, or on carrion, dung piles, or rotting fungi.
Crane flies, those long, gangly insects that look like oversized-mosquitoes, are actually members of the Diptera group as well. They’re kind of creepy in their long-leggedness, but are harmless. They are an extremely difficult group to identify beyond family, and even family is tricky, so I won’t try. Like skinks that will lose their tail if threatened, crane flies easily drop legs, so many individuals have fewer than six. Interestingly, there is a group of wingless crane flies that can be found on the snow surface in northern North America in the middle of winter. Larvae are, for the most part, herbivores or detritivores, and can be a major food source for many sandpipers and other shorebirds, especially in the arctic.
And finally, one of our favourites – the black fly. The have the other common name of “buffalo gnats” for their somewhat humpbacked appearance (presumably they would also bother buffalo, along with everything else). They bite people and other animals for the protein in the blood they take, which allows them to develop their eggs more successfully, although most species can produce viable eggs without taking blood. Larvae are aquatic filter-feeders, securing themselves on a rock or piece of vegetation by a sucker-like bit on their abdomen, and using a string of silk to tether themselves should get get swept off (much the way a spider that gets knocked off doesn’t usually fall all the way to the ground). There are 165 species of black flly just north of Mexico, primarily in the north, which amazes me. This particular individual was dead. Partly because it made it easier to photograph, but also partly because it’s hard not to swat at the things when they bite you. They’re the subject of a popular Ontario folk song:
The black flies, the little black flies
Always the black fly no matter where I go
I’ll die with the black fly a-pickin’ my bones
In north Ontario-io
In north Ontario
seabrookeleckie.com 
Seventeen thousand species, and we recognize only the ones biting us, dancing around dead raccoons, or prancing through the butter. No wonder they have such a bad rep.
Hi – just found your blog through Nature Blog Network, and as an entomologist I really enjoyed this post. Very good job by a non-specialist at researching and assembling into an informative but entertaining post. Great pictures! I’ve linked and will come back to read your previous posts. Best regards, Ted
It does seem a little unfair, doesn’t it, Lavenderbay?
I’m glad you enjoyed the post, Ted! Thanks for stopping by, and I hope you continue to visit!
Your posts have so much good information! I learn a lot by stopping by here! That one on the forget-me-not is beautiful!
Not Suillia , the two orbital bristles are present in Scoliocentra.
The specimen is a female and has been ID as Scoliocentra tincta