388 COTTON 



quite possible that other cotton pests may have been 

 brought in at the same time and in the same way. 



The importation of Egyptian cotton seed into cotton- 

 growing countries zvhere Gelechia gossypiella does not 

 yet exist ought to be strictly prohibited, or else -history 

 may be expected to repeat itself. 



The life-history of the pink boll worm in Egypt is 

 already fairly well known, and in most respects resembles 

 the Indian. Apparently it is in a transition state between 

 a univoltine and a multivoltine insect. 



Some larvae resulting from the October or November 

 broods of moths pass the winter dormant as full-fed 

 larvae, pupating in spring, or even in summer. Out of 

 these pupae some moths emerge early in June and July, 

 others still later in the year, and it appears to be possible 

 (on the authority of Mr. Willcocks) that some specimens 

 emerge so late as to produce larvae that will again hiber- 

 nate. Such insects are consequently strictly single 

 brooded. On the other hand, a large number of the 

 spring pupae give rise to moths/ in June, the progeny of 

 these moths appear in their turn to fly in July and August, 

 and then generation seems to follow generation until 

 the second half of December. Of the larvae of the last 

 generation some pupate and emerge as adults late in 

 December and the first week in January; these are 

 probably lost for the purpose of propagation : others 

 hibernate as larvae, as already stated, and carry on the 

 life of the species. 



The exact length of time required for a generation can 

 consequently be seen to vary from one year to a few 

 weeks. Cold evidently has a retarding influence on the 

 larvae. A large number of larvae extracted from seeds at 

 the end of January were placed in glass tubes. Of these 

 some were kept in an incubator at 37 C., others at 

 27 C., still others at room temperatures varying from 

 10 to 15 C. All the larvae in the two lots at warm 

 temperatures had spun cocoons for themselves at the end 

 of two days; those kept at room temperatures remained 

 torpid, neither moving nor spinning for nine days, after 

 which they began to spin cocoons. Some of the larvae 

 kept at 37 C. started pupating after eight days, others 



