White Bluffs Spokesman

Finds Parasite That Destroys Black Widows' Eggs; May Control the Creature

Spread of the black widow spider may soon be controlled by the laboratory propagation of a rare and tiny parasitic fly that preys on the egg sac of the spider, writes George Elwood Jenks in Nature Magazine.
The fly, known to science as Gaurax araneae, was discovered in Los Angeles about 40 years ago, but apparently was forgotten until Jenks rediscovered it in the spider's egg sacs.
Nature has checks on the undue increase of many creatures in the form of parasites, and it is this minute fly that controls the black widow. Probably assisted by settlement, however, the black widow has been increasing in numbers despite the activities of Gaurax.
The spider spins her sac about the eggs she deposits and remains on guard throughout the incubation period, but it sometimes happens the parasite evades her watchful eyes and succeeds in laying its own eggs on the surface of the sac.
These eggs soon hatch, and the tiny maggots, provided with instinctive knowledge at birth, at once bore through the tough walls of the egg sac to feast on the eggs within
Jenks has experimented in an attempt to propagate this parasite, and has succeeded in raising several thousand under artificial conditions.
The main problem at present is the preparation of a synthetic food for the larval flies that will substitute for the egg sacs of the spider. When this problem is solved, he believes it will be possible to propagate the parasites in insectaries by the million for widespread distribution and thus check the increase of the black widow.