One of the Wild-Caught Gulf Fritillary was Parasitized!

Today we witnessed three huge tachinid fly (Tachinidae) larvae crawling out of one of a Gulf Fritillary (Augraulis vanillae) chrysalis from a wild-caught caterpillar.

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Virtually every species of caterpillar have natural parisitoid enemies. Some species are routinely parasitized such as Monarchs (Danaus Plexippus) with tachinoid wasps (Tachinoidae) while it can be rare in other species. For the record, we have never had any problems with wild-caught Gulf Fritillary (Augraulis vanillae) caterpillars being parasitized -- until today. 

Today we had the honor of witnessing three ridiculously fat maggots eating and crawling their way out of our oldest Gulf Fritillary chrysalis that pupated on 6/29. The chrysalis was made by a wild-caught caterpillar that we caught in fifth instar which we noticed was significantly smaller than the three other wild-caught fifth instars we had (so far, we don't think these three have been parasitized). Being undersized is a typical symptom of being parasitized for pretty obvious reasons -- they are being eaten alive by the parasites!

After the maggots came out, they hardened into extremely round, dark brown pupariums. There are endless species of parasitoid wasps and flies (order Hymenoptera and Diptera) and it is close to impossible to identify them down to the exact genus and species until they emerge, and even then it is difficult. But we can say pretty safely that they are  probably just tachinid flies since parasitoid wasps rarely get this big. When they emerge a week or so later, we will be sure to take some more pics and report back!

- Brian