The distribution and natural history of the gopher tortoise robber fly (Machimus polyphemi Bullington and Beck) (Diptera: Asilidae)

Abstract

The gopher tortoise robber fly, Machimus polyphemi Bullington and Beck (Diptera: Asilidae), is one of 12 species of obligate invertebrate commensals that inhabit burrows excavated by the gopher tortoise (Gopherus polyphemus Daudin), a medium-large terrestrial turtle native to the Coastal Plain of the southeastern United States. Described in 1991, the ecology and distribution of M. polyphemi remains poorly known. From 2019–2025, using a simple method we developed to flush flies from their resident burrows, we detected M. polyphemi at 43 sites in four states, including the first records for Alabama and South Carolina. These data, combined with historic records and community scientist website observations, show that M. polyphemi is more widely distributed than previously thought and essentially a longleaf pine (Pinus palustris Mill.) ecosystem endemic. The majority of sites where M. polyphemi has been documented are sandhill communities, including grossly disturbed examples of this habitat type. We provide size data for adult M. polyphemi, summarize the species’ natural history, and discuss the conservation status of this fascinating insect.

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