131 



•experiments are being undertaken. Control experiments have been 

 successfully conducted against the apple sucker [Psylla inali]. Some 

 progress has been made in investigations on the pea moth [Cydta 

 nigricana], onion maggot [Hylemyia antiqua], carrot rust fly [Psila 

 rosae], and other vegetable pests. 



EssiG (E. O.). Dust Insecticides in California. — //. Econ. Ent., 

 Geneva, N. Y., xiv, no. 5, October 1921, pp. 392-394. [Received 

 13th January 1922.] 



Black-leaf 40, used as a dust, has proved successful in the treatment 

 of various Aphids at a strength of 5 or 6 per cent. Against Aphis 

 malifoliae. Fitch (rosy apple aphis) dusting was begun as the leaf 

 buds opened. A dust containing 6 per cent. Black-leaf 40 was sufficient 

 against melon aphis {Aphis gossypii), Nysius ericae, ShilL, and nymphs 

 of Typhlocyba ( Erythroneura) comes, Say. Adults of the latter were 

 killed by a 10 per cent, mixture. 



The caterpillars of various Lepidoptera also readily succumb to 

 Nicodust treatment, including those of Malacosoma spp. (tent cater- 

 pillars), .Pseudohazis eglanterina, Boisd. (brown day moth), Hyphantria 

 cunea, Drury (fall webworm), and Pymmeis {Vanessa) car did, L. 



Lime liberates the volatile nicotine more readily than kaolin, and 

 is therefore used in preference to the latter as a base for nicotine dusts. 

 The addition of dry sulphur also increases the efficacy of the dust. 

 Black-leaf 40 and sulphur without lime are more efficacious than 

 nicotine and lime without sulphur, but the former mixture, owing to 

 its weight, is not so easily handled in the dusting machines. Nicodust 

 and powdered lead arsenate efficiently controlled caterpillars and flea- 

 beetles, especially the latter on tomatos. 



Morrill (A. W.). Notes on the Use of Nicotine Dusts. — //. Econ. 

 Ent., Geneva, N.Y., xiv, no. 5, October 1921, pp. 394-400. 

 [Received 13th January 1922.] 



As a result of the conflicting reports with regard to the effectiveness 

 of nicotine dusts against grape leaf -hoppers [Typhlocyba conies'] further 

 experiments were undertaken, details of which are described. In the 

 dust tested, 1\ per cent, and 10 per cent, of Black-leaf 40 were used, the 

 analyses showing 2 • 4 per cent, and 3 • 8 per cent, of nicotine respectively. 

 In the former the carrier consisted of 90 per cent, hydrated lime 

 and 10 per cent, sulphur, and in the latter about 75 per cent, sulphur 

 and 25 per cent. lime. Ordinary nicotine dusts appear to be of little 

 value against the adults, but stupify the n\'mphs and cause them to 

 drop. If there are no runners on the ground, and in the case of trellised 

 vines, this is probably equivalent to killing them. 



The results obtained against the melon aphis [Aphis gossypii, Glov.] 

 are similar to those recorded by Campbell [R. A.E., A, ix, 389]. For 

 scattered infestations the author advises dusts with not less than 

 7h per cent. Black-leaf 40. In the case of a general infestation through- 

 out the field it is advisable to use a dust containing only 4 or 5 per cent. 

 Black-leaf 40. The importance of locating incipient colonies of Aphids 

 by scouting early in the season, is emphasised. For cantaloup plants 

 the dust should not contain more than 10 per cent, sulphur to prevent 

 scorching. 



The dust does not apparently aftect natural enemies such as Hippo- 

 damia convergens and Syrphid larvae or the Hymenopterous parasite 

 Aphid ins testae eipes. 



