INSTITUTE, PUSA, FOR 1917-18 85 



present and damages the crop considerably. This latter 

 period covers the cotton-picking season and it is then that 

 P. gossypiella is at its worst. The bollworm parasite, 

 Microbracon — probably more than one species are con- 

 cerned — which normally parasitizes Earias, is also able to 

 parasitize the larvae of P. gossypiella whilst these are in the 

 shoots and pods of the plant; but it seems to be unable to 

 attack the larvae once these have got into the cotton-seeds. 

 Large numbers of the larvae in cotton-seeds were collected 

 and bred out in the quest for parasites but not a single 

 parasite was reared from these. It is undoubtedly owing 

 to the absence of control by"natural parasites that P. gossy- 

 piella is so destructive in some parts of India, notably the 

 United Provinces, and it seems likely that its control will 

 be best effected by the discovery and introduction of an 

 efficient natural parasite. This is not a problem which 

 affects India only, the control of this pest being equally 

 important to Egypt, the United States and practically all 

 the cotton-growing districts throughout the World ; but P. 

 gossypiella is apparently endemic in India and it therefore 

 seems possible that the required parasite, if such exists, is 

 most likely to be found in India. 



As in previous years, the best trap-crop for bollworm 

 larvae was Hibiscus abelmoschus. At the beginning of the 

 cotton season, when Earias were increasing, the pods and 

 shoots of H. abelmoschus were found to contain a relatively 

 larger number of parasitized bollworms than did either 

 cotton or any other trap-crop. The advantage, so far as 

 incidence of insect pests is concerned, of sowing cotton 

 intermixed with another crop was apparent as in the previ- 

 ous year, but Cajanus indicus (tur, arhar) is not a good 

 crop to be inter-sown with cotton. 



Pempheres affinis was very bad this year in the cotton 

 plots and many varieties suffered so badly that they had to 

 be removed. On some varieties Pseudococcus sp. was very 

 destructive, and others were attacked by Machcero.ta 

 planitim so badly that the infested plants had to be removed. 

 A mite, Eriophyes sp., was also bad on a few varieties. 



