482 PKOCEEUTNGS OF THE THIRD ENTOMOLOGICAL MEETING 



The following data were collected by Ballon when working at CairOy 

 relative to the time of flight of moth, as evidenced by traplight captures. 

 The number of moths caught were counted at half-hourly intervals 

 on eight different nights. 



On two occasions the light was turned on one hour before sun-set. 

 Nothing was caught on either of these occasions. 



The total number of moths caught during the eight nights was 4,278 ; 

 of these 3,321 were taken during the first hour after dark during which 

 the light was burning. In this respect it made httle difference whether 

 the light began shining before sun-set or up to two hours after. A later 

 time was not tested ; in every case the bulk of the catch came during 

 the first hour after sun-set during which the light was on. 



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 stragghng way in which the long-cycle larvae complete 

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

 larvee never absolutely ceases, and begins to rise in April, reaching 

 its maximum intensity between May and August, The maximum 

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

 autumn. 



It has already been stated that flowers and buds are attacked to a, 

 much less extent than bolls. A glance at Table II will show that 

 the absolute maximum of infestation of buds and flowers does not 

 coincide with the period of maximum presence of those organs. On 

 the contrary, the Pinl<: Bollworm more readily selects flowers and buds 

 at the end of the season long after their maximum has been passed. 

 The reason for this lies in the fact that at this time the absolute link 

 Bollworm population is greatest, and the supply of green bolls is falling. 

 What green bolls exist are frequently multiply infested. Apparently 

 the stress of over-population drives the insects into attacking buds and 

 flowers which might be considered to be unsuitable. 



Here it may also be remarked that in summer, when cotton bolls 

 are plentiful and not overpopulated, okroe and H. cmmabinus pods are 

 usually not attacked. In September and October when the cotton 

 boll production is falling off, oh'oe ^nd cannahinus pods are increasingly 

 attacked. The apparent immunity of these two species of Hibiscus 

 in summer is due to the cotton acting as a trap-crop and protecting 

 tliem, and not to direct immunity (see Table lY). 



Since 1916 the Entomological Laboratory has every summer made 

 an examination into the intensity of infestation of green bolls by the 



