33 



the increased number of moths which are able to escape in perfect con- 

 dition from a moist, wet soil, as compared with a dry and harder one. 



Abundance of suitable food appears to be a vital necessity for the 

 normal longevity of the moths. Thus, during July and August moths 

 kept without food in the laboratory lived for about six days, which 

 was about half the length of life of females supplied with food. Fur- 

 ther, laboratory records show that oviposition does not really begin until 

 after the female has been able to partake of food. The food of boll- 

 worm moths during the months of July and August, under outdoor 

 conditions, consists partly of such nectar as may be obtained from 

 flowers, but principally of nectar from the nectaries of cotton flowers 

 and squares, and it would appear reasonable that during periods of 

 drought this nectar supply would be far less copious than during 

 rainy weather. Occasional showers would at leas't furnish an abun- 

 dance of water collected at the base of flowers and elsewhere, which 

 the moths have been frequently observed to feed upon. So far as the 

 adult stage of the insect is concerned, there would appear to be some 

 foundation for the belief that the insects are more successful during 

 rainy than dr}^ weather. 



There is but little information bearing on the influence of climatic 

 conditions on the pupal stage of the insect except that pertaining to 

 the effect of low temperatures, which will not be discussed here. 



During the larval or bollworm stage it is most exposed to the attack 

 of parasitic and predaceous insect and other enemies which, on the 

 whole, are much more active during dry than rainy weather. Various 

 species of wasps, principally of the genus Polistes, are very effective 

 predatory enemies of the bollworm. From early in the morning until 

 late in the evening, during fair weather, these insects may be seen 

 busily searching the cotton plants for larvae, and the sum total of boll- 

 worms destroj^ed by these hunters in the course of a single day must 

 result in considerable pecuniary gain to the planter. Rainy weather 

 keeps the large majority of these wasps from the fields, and the boll- 

 worms are thus permitted to develop to that extent unmolested. 

 Other predatory enemies, as tiger and ground beetles and their larvae, 

 robber flies, etc., are also noticeably more active in fair than rainy 

 weather, and the cessation of the attacks of these species during such 

 weather is doubtless an important reason for the more serious depre- 

 dations of the bollworm. 



An important hymenopterous parasite of the smaller bollworms, 

 when on cotton or other plants where the}^ feed more or less exposed, 

 namely, Microplitts nigripennis Ashm., appears, from general observa- 

 tions made during the season of 1904, to be out in greatest abundance 

 during clcjar weather; and this is probabh^ true of other parasitic 

 insects, such as Tachinid and other flies. 



