1961] 
Insect Control Programs 
83 
pupae, many of them imported from Europe and North Africa. Costs 
have ranged up to a half dollar per tip in poor collecting years. 
In i960, after producing several moderately effective synthetic 
lures, M. Jacobson and his co-workers of the Entomology Research 
Division, Agricultural Research Service, USDA, succeeded in isolating 
the principal sex attractant from some half a million female gypsy 
moth tips collected in Connecticut and Spain. The substance was 
prepared synthetically and found to be an ester alcohol with 16 carbon 
atoms in its main chain. In the course of preparing the natural lure, 
a closely related substance (with 18 carbon atoms in its main chain) 
was also found to act as a strong gypsy moth lure. 17 This preparation, 
named gypl-ure , has the advantage that it can be synthesized cheaply 
and in quantity from ricinoleic acid, a common component of castor 
oil. Tested in field traps, quantities of this substance as small as one 
microgram proved equal in luring power to traps baited with the 
natural lure. In 1961, as this is written, field trials are being carried 
out to test the efficacy of gyplure-toxicant combination baits in re- 
ducing moth populations. Included in this program; are “confusion” 
tests with saturated levels of gyplure in granular and spray formula- 
tions. Initial technical difficulties have been met, but it is hoped that 
these can be cleared up during the 1962 season. It will be appreciated 
that many hopes ride on these crucial trials. 
Genetic methods. The success of the screwworm eradication pro- 
gram (see below) has raised the possibility that the release of sterilized 
males might be used to control or eradicate gypsy moth populations. 
This possibility remains to be explored by further studies of the 
moths’ mating behavior and physiology and the practicability of 
rearing, sterilization and release procedures. Sterile male release 
might be made much more effective after reduction of the population 
by bait attractants or other means. 
Other theoretical possibilities for control rest in the fact, discovered 
years ago by R. B. Goldschmidt, that certain different native Old 
World populations of P. dispar differ in their sex-determining mech- 
anisms in such a way that crosses made between them produce inter- 
sexes. It can be argued that the overall fitness of a population might 
be cut by introducing north Japanese strains into the American 
populations, which originated in France. The possibility is worth 
investigation despite some theoretical difficulties. 
THE IMPORTED FIRE ANT 
Introduction 
The fire ants belong to seven or eight New World species in the 
gerninata group of genus Solenopsis. The group as a whole has a 
