Page:Life-histories of Indian insects - Microlepidoptera - T. Bainbrigge Fletcher.djvu/97

28 LIFE-HISTOKIES OF PTEROPHORID^ The following tables give normal life-histories in March- April ; the periods are longer in December- January as stated above : — Eggs laid j Eggs hatched 1 Larva? pupated. Moths emerged Total 23-III 24-III 25-III 27-III 28-III 29-III 14 to 17-IV 16-IV 14-IV 19 to 22-1 V 21-IV 17to]9-IV 27—30 28 23—25 Occurrence. In the life-history as detailed above, there is no stage in which long periods of rest would appear to be undergone and hibernation or any such resting stage would seem to be im-possible. Yet such resting periods must occur in actual fact ; the norm.al foodplant of this insect is the pigeon-pea (Cajanus indicus, known as arJiar, tur or red gram) which is sown with the monsoon^ say in July, and which flowers and bears pods in December- January in some parts of India, in March-April in others. There is thus abundant food for some months only, while this crop is coming into flower and pod, and it is then that it is found in abundance in all stages. The pest has been under fairly close observation in several places and there is a long gap between the crops of pigeon-pea which is apparently bridged in one of several ways. The leguminous plant hulihi or lablab bean {Dolichos lahlah) is an alternative foodplant found in the rains before the pigeon-pea is producing flower-buds, and to a very small extent this insect has been found breeding on this plant. This has not been recorded in Pusa and the only known way in which the moth is known to live over in Pusa from April to December is as an imago in shelter in thick grass. A considerable amount of attention has been paid to the fauna of thick grass and this species has been found occasionally during the months when it is known to breed. It has been found only in this way during this time and only in small numbers in the m.oth stage. We believe that normally it lives over from April to December as a m-oth in hiding, emerging when the pigeon-pea is coming into bud to breed ; in localities where there is a constant supply of its alternative foodplant, it emerges earlier and breeds in small numbers on this. That is, in some locali- ties where hulthi is regularly grown, a summer brood is found on it ; in other places it is not. We may contrast this with Sphenarches caffer which has these two foodplants, but also breeds on Cucurbitaceee, which are freely culti. vated from April to December, so that the latter can find foodplants throughout the year. It is possible that Exelastis atomosa has wild alternative foodplants, but there is as yet no evidence to support this and, had they occurred in Pusa^ we believe they would have been found.