had been eliminated. The me thod as here applied s eems to have marked advantages over the
conventional broadcas ting of ins ecticides. The pois on, an organic phos phorus chemical, is
confined to s quares of fiberboard which are unlikely to be eaten by wildlife; its residues ,
moreove r, are quickly dis s ipated and s o are not potential contaminants of soil or water.
But not all communication in the ins ect world is by s cents that lure or re pel. Sound als o may be
a warning or an attraction. The constant stream of ultrasonic sound that issues from a bat in
flight (serving as a radar system to guide it through darknes s ) is heard by certain moths ,
enabling them to avoid capture. The wing s ounds of approaching parasitic flies warn the larvae
of s ome s awflies to herd togethe r for protection. On the other hand, the s ounds made by
certain wood-boring ins ects enable their paras ites to find them, and to the male mos quito the
wingbeat of the female is a siren s ong.
What us e, if any, can be made of this ability of the ins ect to detect and react to s ound? As yet in
the experi mental stage, but nonetheless interesting, is the initial success in attracting male
mos quitoes to playback recordings of the flight s ound of the female. The males were lured to a
charged grid and s o killed. The repellent effect of burs ts of ultras onic s ound is being tes ted in
Canada agains t corn borer and cutworm moths. Two authorities on animal s ound, Profes s ors
Hubert and Mable Frings of the University of Hawaii, believe that a field method of influencing
the behavior of ins ects with s ound only awaits dis covery of the prope r key to unlock and apply
the vas t exis ting knowledge of ins ect s ound production and reception. Repellent s ounds may
offer greater possibilities than attractants. The Fringses are known for their discovery that
starlings scatter in alarm before a recordi ng of the dis tress cry of one of their fellows ; perhaps
s omewhe re in this fact is a central truth that may be applied to insects. To practical men of
industry the possibilities seem real enough so that at least one major electronic corporation is
prepa ring to s et up a laboratory to tes t them.
Sound is als o being tes ted as an agent of direct des truction. Ultras onic s ound will kill all
mosquito larvae in a laboratory tank; however, it kills other aquatic organisms as well. In other
experiments, blowflies, mealworms, and yellow fever mosquitoes have been killed by airborne
ultras onic s ound in a ma tter of s econds. All s uch experimen ts are firs t s teps toward wholly new
concepts of insect control which the miracles of electronics may some day make a reality....
The new biotic control of insects is not wholly a matter of electronics and gamma radiation and
othe r products of man’s inventive mind. Some of its methods have ancient roots , bas ed on the
knowledge that, like ours elves , ins ects are s ubject to disease. Bacterial infections sweep
through their populations like the plagues of old; under the ons et of a virus their hordes s ic k e n
and die. The occurrence of dis eas e in ins ects was known before the time of A ris totle; the
maladies of the s ilkworm we re celebrate d in me dieval poetry; and through s tudy of the
dis eas es of this s ame ins ect the firs t unders tanding of the principles of infectious dis eas e came
to Pas teur. Ins ects are bes et not only by virus es and bacteria but als o by fungi, protozoa,
micros copic worms , and othe r beings from all that unseen world of minute life that, by and
large, befriends mankind. For the microbes include not only disease organis ms but thos e that
destroy waste matter, make soils fertile, and enter into countless biological processes like
ferme ntation and nitrification. Why s hould the y not als o aid us in the control of ins ects? One of
the firs t to envis ion s uch us e of microorganis ms was the 19th-century zoologist Elie
Metchnikoff. During the concluding decades of the 19th and the firs t half of the 20th centuries
the idea of microbial control was slowly taking form. The firs t conclusive proof that an ins ect
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