Tony Thomas sent this note along with the photos at left:

This larva is "infected" with about 30 eggs of a tachinid fly. They haven't hatched yet and if I leave them they will kill the caterpillar (incidentally they are therefor parasitoids rather than parasites; parasitoids kill, parasites rarely do so). They can't be removed but I will pierce each egg with a pin and this will kill them. There are 10 eggs on the thorax, lots more out of view.

I potted up a Tamarack tree and placed it inside a huge stainless steel bowl. When the larvae hatched, I placed 14 on this tree. I also put 10 larvae, in a large jar, on a cut Tamarack branch that was stuck in a film container of water. The jar was covered with a nylon stocking remnant and a rubber band. In two days the larvae on the living tree were dried up, dead, gone. They just disappeared. Never saw them crawling away. The 10 larvae on the cut Tamarack branch thrived very well. Interesting enough, they never crawled off their branch but just kept munching in the position they were in. In other words, they did not stray off the branch. They all survived and eventually pupated. -- Janice Stiefel