EFFECTS PRODUCED BY PINK BOLLWOEM ON THE YIELD OF COTTON SEED. 281 



compulsory screening of all stores where seed cotton or cotton-seed is kept in the 

 period May to August. 



The pupa is enclosed in a silken cocoon, and is found sometimes in the lint of an 

 open boll, on the soil, under refuse in the fields or between dead leaves. Larvae 

 inhabiting green bolls almost invariably leave the bolls before pupating. During 

 the examination of several hundred thousand bolls in 1916 and 1917 only 2 or 3 

 pupae have been found in green bolls. Larvae which have arrived in a seed store 

 with the seed almost invariably leave the seed-sacks, and pupate in the angle between 

 the line of contact of two sacks or in crevices of the masonry of the walls, or between 

 the floor-boards. The pupal period has been observed to vary from 10 days to 2 weeks ; 

 Busck gives it 10 to 20 days. Control of the insect at this stage is not feasible, as 

 pupae are not easily found in seed stores, even when abundant, and are practically 

 unfindable outside. Before pupating, the caterpillar spins its cocoon, and requires 

 a few days for its transformation. 



Thus short-cycle larvae spin only one cocoon, that in which the pupation takes 

 place, whilst long-cycle larvae spin up inside hollow seeds for their resting period 

 and leave their resting place to spin their pupal cocoon. 



The moth is crepuscular or nocturnal in its habits. During the day it is very 

 difficult to find in fields, or in seed stores, where one knows it to be present ; if 

 disturbed, it escapes by running swiftly and hiding under any shelter it can find. 



During the day-time the moth very rarely takes wing ; but at night it can fly 

 long distances when circumstances are favourable, and is readily attracted to 

 artificial light. Unfortunately light-traps do not form a reliable method of control, 

 and no satisfactory measure against the adults seems possible. 



The pink bollworm breeds continuously from April onwards, as long as there are 

 cotton plants, and especially cotton bolls, for it to feed on. The generations overlap 

 each other, so that one cannot separate the broods. In this respect it resembles 

 Earias. A possible cause for this is the straggling way in which the long-cycle larvae 

 complete their resting stage. At Cairo the emergence of moths from the resting 

 larvae never absolutely ceases, and begins to rise in April, reaching its maximum 

 intensity in June after a gradual and continuous increase. At Alexandria the 

 maximum emergence of moths from resting larvae appears to take place in July. 

 The maximum emergence of moths belonging to short-cycle larvae takes place in 

 the autumn. 



The following general remarks concerning the control of Gelechia may be of use 

 or of interest. 



The campaign as planned in Egypt is directed entirely towards the destruction 

 of resting larvae. To be efficient it must be carried out thoroughly over the whole 

 country. The campaign could be much simplified by changes in cultural methods 

 tending to the production of an earlier crop, or by the introduction of earlier maturing 

 varieties. Should it be possible to force total ripening before the last week of 

 September, or to obtain a plant giving its crop before that date, then the long-cycle 

 larvae could be destroyed by pulling up the plants in the last week of September. 

 A further advantage of an early crop would lie in the fact that the damage due to the 

 attack is to some extent proportionate to the lateness of the harvest, and consequently 

 an early crop would be less likely to be badly damaged. 



