Show Finds Parasite That Tha Destroys Black Blade Widows Widows' Eggs May Control the Creature Spread of the black widow spider may soon oon be controlled by the laboratory laboratory laboratory labo labo- propagation of ot a rare and tiny parasitic fly that preys on the egg sac laC of the spider writes George Elwood Jenks Jenk in Nature Magazine The fly known to science clence as al Gau Gau- rax was discovered in Los Lol Angeles Angelea abou about 40 0 years year ago but apparently apparently ap ape patently was forgotten until Jenks rediscovered It in hi inthe the spiders spider's egg ell sate sacs Nature has checks on the undue Increase of many creatures In hi the form of parasites and It U is ts this minute fly that controls the black widow Probably assisted by settlement however the black wid wide widow ow has been Increasing in numbers despite the activities of The spider spins her sac ac about the eggs she he deposits and remains on guard throughout the incubation period but it sometimes happens the parasite evades evadel her watchful eyes and succeeds in laying its ODell own O eggs ell on the surface of the sac ac These eggs eggl soon oon hatch and the tiny maggots provided with instinctive instinctive tive knowledge at al birth at once onee bore through the tough walls waUa of the egg ell sac ac to feast on the eggs within Jenks has experimented experiment d in an attempt at ate tempt to propagate this parasite and has succeeded In raising several veral thousand under artificial conditions The main problem at present is U the preparation of a synthetic food for forthe forthe forthe the larval flies files that will substitute for the egg ell sacs ac of the spider When this problem is I. solved he believes lit it will b be possible to propagate the parasites In hi by the million rail mil lion for widespread distribution and thus thUi check the Increase of the black widow |