EFFECTS PRODUCED BY PINK BOLLWORM ON THE YIELD OF COTTON SEED. 313 



It occasionally happens that cotton grown in basin lands in Upper Egypt becomes 

 submerged at the end of the season. In 1917 some samples of bolls which had been 

 submerged one week were examined. Forty-three Gelechia larvae were found, of 

 which five were still living. The same bolls contained two dead Earias larvae. 

 Another sample, submerged for two weeks, contained forty-three Gelechia and three 

 Earias larvae, all of which were dead. 



C. Gelechia in Seed Stores. 



During the summer of 1917 we have had the opportunity of making some 

 observations on Gelechia moths in seed-stores at Alexandria. 



On entering a seed-store in the day-time and examining it for Gelechia moths, 

 one never or only very rarely sees moths flying. In order to find living moths it is 

 necessary to look in the darkest places, as the moths hide away during the day-time. 

 If there is a plank or similar object lying on the floor, one almost certainly finds 

 them hiding under it. On being disturbed, they make no attempt to fly, but hurry 

 away, Tunning to find shelter again under some suitable object, such as a board or in 

 a crack in the wall or floor. 



Dead moths may frequently be found by examining under a closed sky-light. In 

 such places the floor is usually littered with them. Other places in the same store 

 may be examined carefully without finding any trace of them. In one store the 

 inner window-sills, which are nearly one metre wide, were found in June to be covered 

 several layers deep with dead Gelechia moths. These windows had the regulation 

 wire screens on their outer aspect, not being closed by glass. 



Where seed was stored in sacks, the angle between two sacks resting on each other 

 appeared to be the favourite place for the larvae to pupate. 



A serious outbreak of Pediculoides ventricosus was raging amongst the Gelechia 

 larvae in Alexandria in June, with unpleasant results to workmen and others whose 

 duties led them into the seed-stores at that period. 



Through the kindness of Messrs. Carver Brothers, Ltd., we were permitted to carry 

 out a trapping experiment in one of their stores at Alexandria during the year June 

 1917 to June 1918. I take this opportunity of thanking this firm for their valuable 

 aid. In this experiment a twenty-five candle-power electric lamp was suspended 

 about 15 cm. above a basin of water, on the surface of which a few spoonfuls of 

 paraffin oil was poured. The basin was about 90 cm. above the ground. The light 

 was allowed to burn all night. Its position was such that only a part of the store 

 was illuminated. Table XXIII gives the details of the weekty catches made by this 

 light, which however do not represent the total numbers of moths present in the store 

 on any day, and must only be taken to represent the comparative frequency. 



The greatest numbers were taken in September, October and November. These 

 constituted almost exclusively short generation moths, whose larvae had been 

 introduced into the store along with the seed. The sudden increase observed during 

 the last week of August and the first week of September was preceded three weeks 

 before by the filling of the store with fresh crop seed from the Fayum. One week 

 before that the store had been quite empty, but had yet given 19 moths in the seven 

 days during which it contained no seed. It will be seen that in the period December 

 to April very few were observed. The quantities of seed in the stores were constantly 

 varying. 



