468 



■WiLLCocKS (F. C). What Effect has Flooding of a Cotton Field by 

 Infiltration from high Nile on the Numbers of the Pink Bollworm 

 in that Field? — Bull. Soc. Entom. d'Egypte, Cairo, no. 4, 

 October-December 1916, pp. 105-108. [Received 20th August 

 1917.] 



Records obtained from lamp-traps used as a possible means of 

 controlling the pink boll-worm, PectinopJiora (Gelechia) gossypiella, 

 appear to show that heavy infiltration from a high Nile is decidedly 

 unfavourable to this moth, as there was a sudden decrease in the 

 number of captures subsequent to the field being flooded. Since 

 P. gossypiella pupates to a very large extent on the ground amongst 

 fallen leaves, etc., it would seem probable that heavy flooding lasting 

 for weeks would be likely to cause the death of the pupae and 

 probably also of pupating larvae. The larvae of Farias insiilana 

 pupate to a much greater extent on the plants and flooding would 

 not affect them so much. This seems to be borne out by the lamp- 

 trap figures. 



GrOUGH (L.). On the Rate of Increase of Gelechia gossypiella Larvae 

 in green Bolls during 1916. — Bull. Soc. Entom. d'Egypte, Cairo, 

 no. 4, October-December 1916, pp. 113-115, 1 diagram. [Received 

 20th August 1917.] 



During the months July to November an investigation was carried 

 out by the Entomological Section of the Ministry of Agriculture with 

 the object of ascertaining the increase of severity of the attack of the 

 larvae of PectinopJiora (Gelechia) gossypiella in green cotton bolls. In 

 all over 120,000 bolls were examined for larvae of P. gossypiella and 

 Earias insiilana. The results are shown in three curves on the diagram 

 accompanying this paper. The first shows the average number of 

 green bolls per 1,000 cotton plants for each week from 8th July to 

 27th October 1916. It rises fairly fast until the first week in August 

 when 8,300 green bolls per 1,000 trees were found, the maximum of 

 nearly 10,200 bolls being reached at a somewhat slower rate during 

 the first week of September. From then it falls until the last date 

 calculated, viz. : — the last week in September, when only about 

 5,200 green bolls per 1,000 trees were recorded. 



The percentage curve for P. gossypiella remains fairly flat until the 

 second week in August (5-9 per cent.), when it rises at a fairly uniform 

 rate until the second week of October, at which time 86 per cent, 

 infestation of green bolls is reached. After this it begins to fall 

 irregularly. 



As against this, the actual number of infested bolls per 1,000 trees 

 increaees slowly from about 270 in the second week of July to about 

 .800 in the second week of August. After this it rises steadily until the 

 third week of September when about 4,500 infested bolls per 1,000 trees 

 is reached. From this time, the actual number falls. 



Earias insulana was relatively unimportant during 1916. It appears 

 to have sunk to the position of a minor pest not only relatively to 

 P. gossypiella, but probably also absolutely. 



