42 



on basket willows in Britain has proved a complete failure. A 

 nicotine-soap solution has been found efl&cient, and this is also the best 

 contact insecticide for Aphids and destroys to some extent the moth 

 caterpillars in the shoots. Sometimes as many as three api^lications 

 are made, but if the willows are well sprayed in late May or early 

 June, it is seldom necessary to spray again in the same year. A form 

 of the Continental apparatus by means of which insects are shaken 

 ofE the trees into trays might be of service in the case of Cryj)torrhynchi(s 

 lapathi, against which sprays are useless. Against the midges causing 

 " button top " no successful treatment has been found, but assuming 

 that the insects pass the winter in the buttons it is undesirable that 

 infested rods should be left in the neighbourhood of the beds until the 

 late spring, when the midges will emerge and attack the new crop. 

 Precautionary measures include the burning of all rubbish, old bark, 

 etc., during the wnter, while old pollarded mllows should not be 

 allowed to remain close to ^villow beds, as they are invariably infested 

 by willow-feeding insects of ail kinds. Neglected and decayed willows, 

 poplars or alders are all undesirable in the neighbourhood of willow 

 beds. Willow stumps that are partly dead or weak should be removed 

 and burnt as soon as the rods are cut. 



Storey (G.). Machines for the Treatment of Cotton Seed against Pink 

 Boll Worm {Gelechia gossypiella, Saund.) — Minist. Agric, Cairo, 

 Tech. & Scient. Service, Bull. no. 14 (Entom. Sect.), 23rd July 

 1917, 29 pp. [Eeceived 23rd November 1917.] 



The question of destroying the larvae of Pectino'phora {Gelechia) 

 gossyjnella (pinli bollworm) in cotton seed has occupied the attention 

 of the entomological section of the Ministry of Agriculture in Egypt 

 since 1912, and since the passing of the law which makes the treatment 

 of cotton seed against this pest compulsory, a great many suggestions 

 for machines for treating cotton seed have been received. These are 

 all briefly described in this paper. 



Fumigation is frequently objected to on account of the poisonous 

 nature of the gases used and the danger involved in the process. The 

 fumigating machines described include the Ministry of Agriculture's 

 original machine [see this Review, Ser. A, iii, p. 505], and one proposed 

 by M. Gayet, both involving the use of carbon bisulphide ; M. Mosseri's 

 fumigator, and an adaptation of the iVmerican baled cotton fumigator, 

 both employing hydrocyanic acid gas. and a machine proposed by 

 Messrs. Wells and Hayman, in which the fumes from the distillation 

 of cotton sticks are used as the killing agent. 



With regard to hot-air machines, some general problems in 

 connection with this method of treatment are discussed. The difficulty 

 of answering the question as to what temperature kills the larvae and 

 what length of time is necessary, is illustrated by a table recording 

 experiments which show the mortality of the caterpillars at difierent 

 temperatures with various methods of treatment. Examination of 

 these results leads to the conclusion that if seed be maintained for 

 five minutes or more at the maximum temperature actually reached 

 by the seed containing the larvae, the latter are killed at temperatures 

 from about 124° F., upwards. If, however, the seed be immediately 

 cooled after reaching its maximum, a temperature of at least 140° F. is 



