Death Cycle Part 3: The Insects

Photography by Parker Grice
Within half an hour of its death, the roadkilled squirrel was agleam with golden-green blowflies. They clustered especially around the bloody face. I could see them packing themselves into the mouth. Others were clustered under the belly. Maybe the squirrel had been wounded there, though I hadn't noticed any wounds when I placed the carcass on the roof.

Blowflies are often the first scavengers to arrive at a kill. They can smell death from miles away. Their mission is not only to eat, but to lay eggs. Their maggots often do more than any other animal to dismantle a carcass. In hot weather, their eggs may progress to larvae and then to pupae in only a few days.

I wasn't surprised to see the flies, but I was surprised by what I saw flying among them. It was a yellow-and-black wasp. I don't know the name of the species, though I've seen it many times buzzing innocuously around my yard. It's a smallish wasp, hardly bigger than the blowflies. I'd really never even been concerned about its sting, because I see so many more formidable wasps. I'd also never given much thought to what this kind of wasp eats.

As the wasp flew around, it seemed remarkably clumsy, because it kept colliding with flies. I thought it was trying to muscle through the flies for a better feeding position on the carcass. Then the wasp and a blowfly fell struggling to the shed roof, grappling on the shingle. In a moment the wasp flew away, graceful now, and the blowfly was in her grip. Since they were roughly equal in size, I was surprised the wasp could lift her victim and cruise away with such apparent ease.

The wasp, or one who looked just like her, returned and took another victim. This time I saw her flying among the flies but didn't see her grapple with one. She flew away and I thought she was going empty-handed, but as she turned in the air I saw the dark gleam of a blowfly.

A wasp, depending on its species, make several uses of a fly. Some worker wasps chew up other insects as food for the young of the hive, spitting it directly into the waving mouthparts of the larvae. Among solitary wasps, many paralyze other arthropods with a sting, lay eggs on them, and seal them up in nest of some sort. The hatchling wasp larva then eats the victim, usually without killing it for a long time.

I saw several of these wasps at work over the course of this little adventure. They were the first scavengers to arrive when light came the next day, three of them struggling to get into the squirrel's mouth or under its belly. I wasn't sure what they were doing at that point, since there were no blowflies to prey on at that cool hour. They may have been eating flesh from the carcass. Or could they have been interested in the eggs and larvae of the flies?

There's more to come, including a startling scavenger in the night.




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