82 
Psyche 
[June-September 
baiting with attractants, and genetic disruption. In briefly discussing 
these topics, we should not overlook the possibility that there may exist 
entirely different modes of attacking the problem that have not yet 
occurred to anyone. 
Predators and parasites. As already mentioned, a number of 
predaceous, parasitic and parasitoid insects, mainly beetles, flies and 
wasplike types, have been successfully colonized in the United States 
after being brought from Europe and Asia. Different ones attack 
every stage of the moth, from egg through adult, but few of them are 
strictly specific to the gypsy moth. The efficacy of the parasites is 
now open to question, since they have obviously not prevented serious 
outbreaks in areas where they are known to be established. Never- 
theless, some natural enemies are known to be very effective at high 
densities of the host, and their value in the absence of possibly disturb- 
ing chemical control has not been thoroughly checked in recent years. 
Furthermore, it is likely that the established introductions represent 
only a fraction of the potentially useful arthropod enemies of the moth 
existing in Eurasia or elsewhere. In theory at least, there remains the 
possibility of keeping the moth at a tolerable population level by 
means of natural enemies, especially if used in conjunction with other 
biological control methods. Further research on natural enemies of 
the moth would certainly be desirable. 
Disease propagation. The gypsy moth larva is susceptible to certain 
bacterial and viral diseases, among which Bacillus thuringiensis shows 
enough promise to have stimulated large-scale tests by Federal and 
state agencies. These tests, only partly completed, employ a “sticker” 
of tung oil or one of the improved English Eovol products to fasten 
the bacterial spores to the foliage. The suspension of spores in sticker 
can be sprayed from the air, and presumably is not harmful to plants 
or wildlife. So far, results have not been encouraging. 
Attractants. The female gypsy moth, as already stated, can flutter 
along the ground or over low plants, but she cannot truly fly for any 
distance. The strong-flying males, like those of many moths, are 
strongly activated, even over long distances, by scent released by the 
female from the terminal segments or “tip” of her abdomen. Upon 
sensing even minute amounts of this scent, the male responds by flying 
upwind, in this way automatically approaching the scent-producing 
female, and ultimately coming near enough to mate with her. The 
scent obtained by extracting the female tips in benzol has been used 
for years as a lure in metal or paper traps to survey suspected areas 
in order to determine whether males, and therefore a likely infestation, 
are present. The female tips are obtained by the laborious and 
extremely expensive rearing of thousands of hand-collected female 
