450 



from six to nine days. The feeding period covers about four weeks in 

 summer, but there are considerable variations in the duration of the 

 hfe-cycle. From early September onwards it begins to lengthen, and 

 continues throughout the winter, though only the more hardy individuals 

 survive and development is much retarded. Hibernation occurs in 

 the egg-stage, ovisacs being found in numbers in crevices of the bark. 

 Males never occur in any quantity, the maximum being reached in 

 September, when the proportion is about 1 to ever}- 500 females. 

 Reproduction during the summer is parthenogenetic ; the males 

 appearing late in the year may give rise to a hardier generation to 

 meet winter conditions. 



Fumigation is effective against P. hirsutus, but a heavier dose is 

 required than for the black scale of orange [Saissetia oleae], and it is 

 almost impracticable owing to the variation in the nature and size of 

 the trees attacked. Spraying with paraffin emulsion is effective when 

 accompanied by pruning, but reinfestation, which almost invariably 

 follows in Cairo, is then worse than before. Moreover, the young 

 growing shoots become so gnarled in consequence of infestation that 

 no spray can penetrate. The substitution of less susceptible varieties 

 of trees is recommended. Legislation enacted during the past three 

 years, prohibiting transport of infected plants and fruits and enforcing 

 the cleaning of infested areas, has done much to prevent the spread 

 of the pest. 



Debski (B.). Descriptions d'une Cecidie et de I'Insecte qui la provoque : 

 Psectrosema alfierii, nov. spec. (Cecidomyidae), comparees a celles 



du Psectrosema debskii (Kieffer 1912). — Bull. Soc. Ent. d' Egvpte, 

 Cairo, xiv (1921), 1922, pp. 32-51. 



A description is given of Psectrosema alfierii, sp. n., forming galls on 

 Tamarix spp., and of the resulting deformation of the tree. 



Bedford (H. W.). The Asal of Cotton and its Causes in the Sudan. — 



Wellcome Trop. Res. Lab., Khartoum, Ent. Sec, Bull. 17, 

 November 1921, 8 pp., 2 figs. [Received 5th July 1922.] 



The sticky substance sometimes found on cotton plants in the Sudan, 

 where it is known as asal, may be due to an excessive secretion of sticky 

 fluid by the plant itself or to the presence of insects that secrete a 

 similar substance. 



The secretion has a definitely injurious effect on the plant. The 

 various sources of it are briefly described, the insects involved being 

 Aphis gossypii, Glov. (cotton aphis), Heliothrips indicus, Bagn. (cotton 

 thrips) and Aleurodids. 



Bedford (H. W.). The Cotton Thrips {Heliothrips indicus, Bagiiall) 

 in the Sudan. — Wellcome Trop. Res. Lab., Khartoum, Ent. Sec, 

 Bull. 18, November 1921, 52 pp., 5 plates. Price 2s. [Received 

 5th July 1922.] 



The life-history and habits of Heliothrips indicus, Bagn., in the 

 Gezira are described, most of the information having alreadv been 

 noticed [R.A.E., A, vih, 497J. 



The natural enemies so far observed have not been seen in sufficiently 

 large numbers to keep the thrips under control. A brief account is 



