MABON AND LEFfcOY. 367 



comes down to the soil, pupating on the leaf. This does not apply 

 to caterpillars feeding on low plants that a Mynah for instance can 

 get at, and for all caterpillars that pupate in the soil, as the Sphin- 

 gids, there is that risky period when they must descend and seek a 

 place to burrow into the soil. Most do so at night but many pro. 

 bably perish and in a big caterpillar attack, it is very striking to see 

 the birds collect to feed when the caterpillars descend to pupate ; 

 we use this in fighting caterpillar attacks by cutting bands of the 

 crop across which the caterpillars can pass only on the soil where 

 the birds can get them and from the rapidity with which birds come 

 it is evident they watch insects pretty closely. The reason so many 

 Noctuid larvaa hide during the day is probably simply to escape the 

 birds, and if one watches caterpillars one can get a picture of the 

 ceaseless watch kept by the birds and the ceaseless attempts of the 

 caterpillars to evade them. Apart from direct observation one can 

 infer it by the devices so common among caterpillars to escape 

 the observation of, not parasites, but birds. This is a subject that 

 could be discussed in very great detail, but would be out of place 

 here. 



In estimating the actual food of birds, one must remember that 

 caterpillars are soft, are very often squashed or torn by the bird 

 in or before the process of eating and are not easy to recognise at all. 

 Our knowledge of Indian caterpillars is not detailed ; we have had 

 to collect and compare caterpillars of many kinds in India to be able 

 to recognise even our pests from the caterpillar stage alone and as a 

 rule when a bird has taken caterpillars one cannot identify them ; 

 we have to rely more upon observation than upon detailed stomach 

 records. I attribute to birds a very great role in checking caterpil- 

 lars alone, and I believe that the reason why a big caterpillar out- 

 break is seldom followed by another big brood is due to the work 

 of birds in catching the pupating Iarva3 as much as to the action of 

 parasites. If this is true, then the direct action of birds in preserv- 

 ing crops is immensely important, but it is a matter difficult of direct 

 proof and must depend upon one's personal estimate of the influence 

 of birds. 



