(Diptera: Sciaridae) Larvae - mass processions

snake worms

A number of sightings of strange migrating "worms" were reported from at least five sites in and around Fairbanks, Alaska during mid to late July, 2007 and in subsequent years. Three of these sites are close to one another (within 10 miles) around Old Nenana highway and Ester. One sighting was made off Ballaine Road in Fairbanks and a third in North Pole.

These worms turned out to be larvae of a species of dusky winged fungus gnat (Order: Diptera, Family: Sciaridae). The behavior is rare and poorly understood. It is also completely fascinating! As far as is known, this is the first sighting of this behavior in Alaska (although these fungus gnats certainly are a normal member of the fauna - they don't normally migrate like this).

Such migrations have been reported before from various parts of the world, and the larvae are sometimes referred to as "Army Worms" in Europe and "Snakeworms" in North America.

One of the better write-ups of the phenomenon was written by Brues in 1951 based on an experience he had with them in the Philippines. A link to this paper follows:

C. T. Brues. A Migrating Army of Sciarid Larvae in the Philippines. Psyche 58:73-76, 1951.
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In 2023 this investigation was published as a research article describing the Alaskan snakeworm gnats as a new species: Sciara serpens Pereira, Heller, Sutou

Thalles P. Lavinscky Pereira, Kai Heller, Mitsuaki Sutou, and Derek S. Sikes (2023) "Discovery of snakeworm gnats in Alaska: a new species of Sciara Meigen (Diptera: Sciaridae) based on morphological, molecular, and citizen science data," Integrative Systematics: Stuttgart Contributions to Natural History 6(2), 91-111, (30 December 2023). https://doi.org/10.18476/2023.673937

Dr. Derek S. Sikes, Curator of Insects at the University of Alaska Museum has been recording information on these sightings. If you have seen snakeworms migrating, please call Dr. Sikes at 907-474-6278 or email at dssikes@alaska.edu