ARTHROPOD MUSEUM NOTES

Number 57 • July 1, 2008 • Jeffrey K. Barnes


Snake-worm
Order: Diptera
Family: Sciaridae

snake worm

Snake-wormMembers of the fly family Sciaridae are known as darkwinged fungus gnats. They are often found in dark, shady places, such as forests, caves, and animal burrows.  Their larvae have a shiny black head capsule and a twelve-segmented, white-translucent body. They are scavengers, feeding on decaying plant material, animal excrement, or fungi.  Some are found in rotting wood or under the bark of fallen trees.  Mass migrations by larvae of some species have been well documented, but the purpose of these movements remains unknown.  In 1951, Harvard entomology professor Carles T. Brues published a note on the mass migration of an army of fungus-gnat larvae -- a snake-worm -- that he observed in a Philippines rain forest.  The individual larvae move on the bodies of their comrades.  Progression of the whole snake-worm is accomplished by the forward movement of the individuals on top of the worm.  As the mass moves forward, the larvae are constantly changing position with respect to one another.  Dr. Brues' snake-worm consisted of fully grown individuals of uniform size, suggesting that they were searching for a suitable pupation site on drier ground than that from which they were escaping.  Similar observations have been made several times in Europe, the United States, and elsewhere.  Snake-worms are usually little more than a foot long, but at least one observer reported a worm five feet long.