Thursday, July 13, 2017
Monarch Caterpillar Fly Parasite
But in nature there are many battles every species needs to constantly fight to have its population stay healthy and survive to reproduce the next generation.
For the Monarch a parasitic tachinid fly is one of the battles it must face.
The eggs hatch and burrow into the insides of the caterpillar, feeding on non-vital tissue, so the caterpillar can stay healthy enough to keep eating, providing more food for these parasites.
The fly larvae, which are small white maggots, continue to eat inside the caterpillar until they are ready to pupate, the stage of metamorphosis in which they will prepare to turn into adult flies. To do this the maggots have to leave the caterpillar and drop to the ground.
After the fly maggots eat an exit hole in the caterpillar or chrysalis, and drop to the ground, the Monarch caterpillar or chrysalis always dies. Its vital organs finally having been eaten by the maggots before they left.
Below are eight pupae of the parasitic tachinid fly shortly after they emerged from a Monarch chrysalis 11 days ago.
They stayed like this for ten days, and began to emerge as adult flies yesterday.
The two gray antenna on the front of the face seem slightly different than other flies.
The pattern on the back seems a little more pronounced than some flies.
The face down below would only be appealing to another tachinid fly.