376 ENTOMOLOGY 



Reproduction.- It goes without saying that constant feeding is 

 necessary in the case of long-lived prolific females, such as queen bees, 

 ants, or termites. 



With plant lice, it has long been known that the drying up of the 

 food plant causes the appearance of large numbers of winged, or migrant 

 females. In experiments with the. pea louse, Macrosiphum pisi, it 

 was found that the subjection of parthenogenetic (reproducing without 

 fertilization) females to periods of partial starvation induced the produc- 

 tion of winged offspring from the wingless mothers. These winged 

 young would otherwise have been wingless, as check experiments 

 showed. (L. H. Gregory.) 



In regard to the relation of food to the production of the males and 

 oviparous (egg-laying) females of plant lice, not much seems to be 

 definitely known. 



Fecundity. The kind and amount of food influence fecundity. If 

 female boll weevils are fed on leaves alone, eggs do not develop; while 

 a diet of squares leads to the development of eggs in about four days. 

 More eggs are laid when squares are abundant than when they are few. 

 (Hunter and Pierce.) 



Guyenot found that pomace flies (Drosophila) reared from aseptic 

 larvae on sterile potato (without yeast) did not produce offspring. The 

 flies themselves, if fed on potato alone, were much less prolific than when 

 fed on potato and yeast. 



Oviposition. With many adult insects feeding is not necessary for 

 oviposition;in fact the mouth parts are often rudimentary, as in some 

 of the moths. Such insects owe their activity to the presence of a 

 supply of food stored up by the larva. Other insects, however, must 

 feed in order to lay eggs; the queen honey bee, for example. 



Adults of Pteromalus puparum, a parasite of the cabbage butterfly, 

 Pieris rapa, if kept without food for three days, attempt to oviposit 

 but are physically unable to do so. If then fed, however, with honey- 

 water or with blood from punctured chrysalides (their natural food), 

 they succeed in drilling into the chrysalides of their hosts. When 

 supplied with fresh pupae one of these females may feed and lay eggs 

 for three weeks; and if given honey- water also, for two months. 

 (S. B. Doten.) 



Sex-determination. One of the most plausible of the theories of 

 sex-determination has been that high nutrition produces females and low 

 nutrition, males. In raising moths or butterflies from caterpillars 

 males and females occur in about equal numbers, as a rule. If, however, 



