Sunday, June 19, 2011
Flies as Decomposers-Disgusting but Necessary
A squirrel was killed by a car in front of my house this weekend, and I set it in the grass until I finished a short errand. One half hour later there were flies all around it.
So I set it on a table, like any normal person, so I could photograph the flies doing whatever they do.
I've seen this hundreds of times, but never really watched it up close.
Squirrel fur is a thick forest to flies trying to find a place to lay their eggs. So they focus on natural entry areas, in this case, the mouth and nose.
All of the flies present were the same species, as you can see in the pictures below, and the only thing they did was lay eggs. For 6 hours. In the nose and the mouth.
The female flies have a long tube at the end of their abdomen called an ovipositor. The eggs travel down this "tube" and are placed where the female's instincts tell her to place them-in this case, inside the dead squirrel's mouth and nose. That will give her babies access to the soft tissue as soon as they hatch.
You can see the flies in these two pictures pushing their abdomens into the openings of the mouth and nose, and the following picture shows how these openings were completely filled with eggs.
While not a pretty sight, just think what it would be like if nothing ate these dead animals! Flies are very busy cleaning things up for us and get very little credit for their unsavory jobs.
Eating for these flies is not chewing out a chunk of flesh and chewing it up. These flies have a fleshy appendage for a mouth with a sponge like blob on the end. They push this around on liquidy surfaces and soak up their food.
You can see this fly doing just that on the squirrel's eye in this picture from 11 AM this morning. These flies were wary and would not come close if I moved.
I may not continue this investigation, as the smell will not be welcomed by others nearby, not to mention my own enjoyment of my yard.
Keep doing your stuff, decomposers, down wind if possible.