230 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



The moth is a dull olive-gray color with a wing expanse of 

 about 1 J inches, which sometimes have a purplish lustre, and which 

 are marked with darker lines as shown in Fig. 191. Like most of 

 the owlet moths it flies only after sunset, but unlike them, it is 

 not confined to the nectar of flowers for food, as its mouth is 

 peculiarly adapted to piercing the skin of ripe fruit and feeding 

 upon its juices. Injury by the cotton worm moth to ripened 

 peaches is frequently noticed in the peach orchards of West 

 Virginia and regions farther north. The moths are strong fliers, 

 those of the later broods being frequently found as far north as 

 Canada. 



The first two generations develop rapidly and in the extreme 

 South the moths emerge by early April and are carried north- 

 ward by the prevailing winds. Eggs deposited by them give 

 rise to a brood of moths which in turn fly farther northward, 

 and thus the worms are gradually found throughout the whole 

 cotton belt, though with a considerable confusion between the 

 various generations. At least seven generations occur on 

 the Gulf Coast, and three at the northern limit of the species. 

 Considering the number of eggs laid by each female and 

 this number of generations, it may be readily perceived how 

 such immense numbers of the caterpillars may arise by the latter 

 part of the season, in a region where practically none remain 

 over winter. If none was killed, the progeny of a single moth 

 after four generations would amount to over 300,000,000,000 

 individuals, or if placed end to end, the third generation would 

 be enough to encircle the earth at the equator over four times. 



Enemies. It is thus very fortunate that there are many 

 deadly enemies of the cotton worms, which commence their war- 

 fare upon them with their first appearance in spring and continue 

 it with increasing ardor throughout the season. One of the most 

 effective of these is a minute little insect, Trichogramma pretiosa, 

 which develops within the eggs. Mr. H. G. Hubbard once 

 observed that in Florida from 75 to 90 per cent of the fourth 

 brood of eggs were destroyed by this parasite, while only three 

 or four eggs in a hundred escaped in the sixth brood. Another 

 of the most useful parasites, Pimpla conquisitor, was noticed as 

 early as 1847 to destroy nearly all of the pupae of the last brood. 

 The eggs 'of the Pimpla are laid upon the caterpillar, and the 



