32 LIFE HISTORY AND HABITS. 



hibernation have one brood between the cold and hot weather and then 

 become torpid, either from absence of food or from the excessively hot 

 and dry conditions. In many cases this period is simply a continuation 

 of the hibernation ; the torpidity due in the first place to cold appears to 

 g-ive place to a torpidity due to heat and drought ; or we may consider 

 it as due to the absence of food. For many species there is food 

 only during' the wet season, so that insects emerg-ing- too soon would 



find no food. 



On the other hand, we find insects emerging" at the commencement 

 of the hot weather, living as imagines till the rains if food is not available, 

 but laying eggs and producing a new brood if food is available. This is 

 a ciTriously interesting fact not yet fully understood. For instance, if 

 cotton grows continuously through the cold weather and the hot weather, 

 we find its pests attacking it at the commencement of the hot weather ; 

 should the cotton however be dead, we find the same insects apparently 

 living as imagines or still hibernating. When well irrigation is practised 

 in the hot weather, there is food for some insects in the irrigated crops, 

 with the resiilt that these insects are found breeding in March or April ; 

 in the same district, where well irrigation is not practised, we find these 

 insects still hibernating or living in concealment as imagines. These are 

 perhaps the exceptional cases, but they are common among the crop- 

 destroying insects. 



A larger number of insects appear to continue torpid after the cold 

 weather and until the rains. But again, such is the variety of insect 

 life that general statements are of little use. Many insects are most 

 active in the dry hot weather ; the wasps make nests, the first parasites 

 appear, the dung-rolling beetles are seen. Ants, termites and other 

 insects are active. If we turn to crop pests, it is not far from the truth 

 to say that (1) they continue hibernation or (2) they emerge and lay 

 eggs on the crops if available or (3) they live as imagines until the rains. 

 The question of available food-plants is apparently the decisive factor ; 

 sugarcane pests are very active in the hot weather, but the conditions of 

 course approximate to those of the ]'ains, there being food and moisture 

 available. 



The result of these periods of rest is that for every species there is a 

 definite time during which the imagines emerge and lay eggs. IXiring 

 one week there will be an abundance of a particular moth emerged from 

 hibernation. The period may be longer or shorter, but there is for every 

 species some period, at the commencement of the rains or of the hot 

 weather, when ep-gs are laid, and shortly after which the first brood of 

 Caterpillars emerges. If all the imagines emerged on the same day, we 



