280 DR. L. H. GOUGH. 



The larval stage is passed, almost entirely, inside the part of the plant attacked. 

 The time required for this stage as given by Willcocks is 9-19 days ; Busck gives 

 20-30 days. The feeding period is immediately followed in summer by spinning up 

 and pupation ; but in the case of larvae whose feeding period closes in the late autumn 

 or winter it is followed by a resting period, which can last as long as two and a half 

 years, and perhaps longer. We apply the terms " short cycle " larvae to those 

 which pupate immediately after feeding and " long cycle " or " resting " larvae 

 to such as intercalate a long period of rest between feeding and pupating. Resting 

 larvae are usually found spun up inside hollow seeds, or " double " seeds. A 

 " double " seed is produced in the following manner. The larva having hollowed 

 out a seed, attaches another seed to the hollow one, uniting the edges of the opening 

 of the hollow seed to the new seed by silk threads. The attachment of the two seeds 

 to each other is very firm and resists the action of the gins. The second seed is 

 usually eaten into. When no second seed is used, resting larvae spin up the opening 

 of the seed they inhabit ; double seeds often contain two caterpillars. It is not 

 an infrequent occurrence for larvae to use more than two seeds for their resting shelter ; 

 as many as six seeds have been found utilised in this way. The seeds composing 

 " double " seeds usually vary in their state of maturity. The original hollow one 

 is generally in the red unripe stage of development, the next seed or seeds being 

 black or ripe. 



The presence of Gelechia* larvae in attacked green bolls cannot be noticed without 

 cutting open the boll, as the entrance hole made by the larva is very minute, and 

 the larva does not keep it open or enlarge it in order to void the frass as Earias larvae 

 do. For this reason it is not possible to control the pink bollworm by collecting 

 attacked green bolls. When full-fed, short-cycle larvae leave the bolls by a hole 

 which might be mistaken for the work of an Earias larva, but that the frass left 

 by such larvae is wanting. 



The resting stage does not appear to be entered into by many larvae (in Egypt) 

 at the time of the first picking ; on the other hand many, if not most, of the larvae 

 present at the time of the second picking are either already resting, or intercalate 

 a resting period between feeding and pupating. This stage, as already mentioned, 

 may last as long as two and a half years. 



It is the resting stage larvae which (in Egypt) serve to carry the species over from 

 one year to the other. They are found almost exclusively in seed, whether in seed 

 cotton, ginned seed or in abandoned bolls in the field. Besting larvae probably do 

 not feed, as they lose weight continuously from February to June (see below). 



The resting stage is the only period of the life-cycle of the pink bollworm during 

 which it can be controlled, and acting on the advice of the Entomological Section 

 of the Ministry of Agriculture, the Egyptian legislator has seized the opportunity 

 afforded by the insect to ensure its destruction, (a) in the cotton field, by ordering the 

 pulling up of the cotton-sticks and the destruction of the remaining bolls after the 

 last picking, and consequently ensuring the elimination of the larvae left in the field ; 

 (b) by the treatment by heat or fumigation of the seed in the ginneries ; and (c) by 



* The generic name Gelechia has been retained throughout, as being more familiar, 

 especially to Egyptian readers. 



mu. 



