LEAF-EATING CATERPILLARS. 185 



brood in July, another in September and then hibernation. Such 

 general statements can only be accepted very cautiously as the habits 

 vary with individual species. 



It is not possible to give a list of the species which attack indivi- 

 dual crops and such a list would serve no useful purpose. A detailed 

 account has been given of several species (pages 96, 159, etc.). Rice is the 

 food of many species, which are also grass feeders; the large area under rice 

 usually allows for a large number of such caterpillars being widely spread 

 so that the damage is distributed, but exceptionally they are so abundant 

 as to cause serious injury. Some crops are apparently not attacked by 

 caterpillars,, such as the various yams (Lioscorea and Colocasia), and the 

 tapioca (Manihot). Leaf -eating caterpillars are destructive principally in 

 small areas of irrigated crops or in patches of special crops not 

 generally grown in the district. The fields of mixed crops, grown to 

 a limited extent in April, May and June, usually with well irrigation, 

 suffer heavily from this pest, as many moths emerge from hibernation 

 at this time and lay eggs on a small area of crop. Later in the year 

 the same caterpillars may be spread over a far larger area of staple crops 

 with no appreciable harm. The same may be said of special crops of 

 which only a small area is grown ; this applies particularly to experi- 

 mental farms and is one of the reasons why crops grown on experimental 

 farms suffer to so large an extent from insect pests. 



In general, each species of caterpillar feeds only on a few closely 

 related plants ; thus there are species which feed only on cotton, bhindi, 

 ambadi (Hibiscus cannaliiius] and hibiscus, others on maize and sorghum 

 or on cabbage, rape and mustard. A small number have a greater 

 range of food-plants, such as the omnivorous Gram Caterpillar (page 144) 

 which eats gram, opium, tobacco, tipari, tomato, maize, etc. It may 

 be remembered that the caterpillars have no choice of food-plant in 

 most cases, since they can move over only short distances, but the moths 

 seek out the right plant on which to lay their eggs, their instinct 

 telling them on which plants their young will be able to feed. If no 

 plants are found the moths can live for a considerable period before 

 laying eggs. 



Treatment. There are several simple methods of checking leaf- 

 eating caterpillars and of preventing them from becoming serious 

 pests. The simplest method is to pick them off by hand ; it is of course 

 useless then to liberate them near the field from which they were taken 

 as the cultivator sometimes does, but they must be destroyed. In most 

 cases the destruction of the first brood prevents the injury caused by the 

 otherwise large second brood j unfortunately the first brood commonly 



