158 



occurred, the shoots with dead-hearts were cut back to ground and 

 the side shoots allowed to grow up. If caterpillars were still found 

 in the portion of the stump remaining in the ground they were picked 

 out and killed. Plants so treated gave a very good yield. An attempt 

 was made to rear the Tachinid parasites on a large scale in the insectary ; 

 oviposition, however, did not occur in the rearing cages, but further 

 trials are in progress. Unfortunately, these flies cannot be satis- 

 factorily reared in winter under artificial conditions. 



S. inferens does not kill the plant outright, but it decreases the 

 yield of grain in the ear-heads. After the crop is harvested, the 

 insects enter the offshoots given out from stumps remaining in the 

 ground, where they breed even in summer. During severe winter 

 weather the caterpillars hibernate in the stalks. After the harvest, 

 therefore, the stalks remaining in the ground should be dug out and 

 burnt, or split up and used for chaff. A Braconid parasite infests 

 these caterpillars, but it is not very efficient. The best remedy is 

 the immediate removal of the stumps remaining in the ground after 

 harvest, and burning them to prevent further breeding. Many borers 

 were found in the harvested stalks of Sorghum ; those that are being 

 dried and stored as fodder for cattle and that contain hibernating 

 larvae should, therefore, be made into chaff by power or hand-machine, 

 which will destroy the majority of the insects. 



Mr. T. Bainbrigge Fletcher, in discussing this paper, remarked 

 that the subject of sugar-cane borers is a very important one ; that 

 the names of many of them are still very uncertain, and that the 

 determination of the adults requires further study. ' 



HusAiN (M. A.) & Pruthi (H. S.). Preliminary Note on Winter 

 Spraying against Mango Hopper [Idiocerus spp.), vernacular name, 



Tela. — Rept. Proc. 4th Ent. Meeting, Pusa, February 1921, 

 Calcutta, 1921, pp. 148-152. 



The most serious pests of mangos in the Punjab are Idiocerus spp. 

 (mango hoppers), of which I. atkinsoni is the species most commonly 

 found. Hoppers that have survived the winter come out from under 

 the bark in the spring and cluster on the floral buds, where they 

 extract the sap from the growing inflorescence. Oviposition begins 

 when the blossom heads appear, about the second or third week in 

 February. N3miphs are first seen in March, and become adult in 

 about 18 to 20 days. There is apparently only one generation a year, 

 eleven months being spent as an adult, in which stage hibernation 

 occurs. As a result of the feeding of the nymphs, the flowers shrivel, 

 turn brown, and ultimately fall off. Old gardens, where the trees 

 are closely grown, and particularly in regions having a hot and slightly 

 moist climate, are especially affected. When mature, the hoppers 

 leave the blossoms for the stems, where they collect in large numbers 

 on the lower surfaces of the lower branches of the trees in the daytime, 

 and underneath the leaves in the morning and evening. During the 

 winter they are very inert and shelter in the crevices of the stems 

 or among leaves weljbed by spiders. 



As the breeding season coincides with the flowering of the trees, 

 spraying in the nymphal stage is likely to kill the flowers. The opened 

 mango flowers are too delicate to stand a forcible spray, even of warm 

 water. Winter sprays were, therefore, tried, and were used between 

 6 and 9.30 a.m., when the hoppers were least active. It was found 

 that resin, with a strong contact poison, such as soHgnum or crude oil 



