Subject: What is the name of this fly?
Location: Catalina Island
August 4, 2012 2:08 am
I saw this interesting fly on a plant on the Wrigley Botanical Garden and could not find it listed in any Catalina Island guidebook. I believe the order is Diptera. Can you identify the family, genus and species, please?
This is one of the Tachinid Flies in the family Tachinidae. Tachinid Flies are a diverse family, and according to Charles Hogue in Insects of the Los Angeles Basin: “Most species of this group resemble overgrown House Flies but are covered with extra-heavy stiff bristles. The thorax is usually a solid color and is not banded lengthwise as it is in other domestic flies. Tachinid Flies are often seen flying closely over or crawling through low vegetation in search of insect larvae (cutworms and the like) upon which to lay their eggs. The larvae are parasitoids that feed internally on the host; as the hosts are caterpillars, including cutworms and loopers, Tachinid Flies are considered beneficial to the gardener and farmer.” We believe this is the Spiny Tachina Fly, Paradejeania rutilioides, based on images posted to BugGuide and the range which is the southwest portion of North America. Often island populations evolve into distinct subspecies and we are not certain if this is the case with the Santa Catalina Island population. BugGuide lists the host as the larvae of Edwards’ Glassy-Wing, a species of Tiger Moth that feeds on oak in its larval stage.