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(Diptera: Sciaridae) Larvae - mass processions

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. 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 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"

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

A photogallery of images taken by Museum Volunteer Margaret Billington and Dr. Sikes shows these larvae in detail:

Gallery

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