30 



■obtained it appears that dusting is rather more effective than sprajdng, 

 but it was not possible to estimate accurately the relative expense of 

 the two methods. 



A small number of predacious spiders were collected in material 

 from the sprayed and dusted plots, but generally they appeared to 

 be resistant. In only one case were the leafhopper egg parasites 

 found in numbers. On one dusted plot 80 Ootetrastichiis heatus, 

 50 0. formosanns and 270 Mymarid parasites were found, and on 

 the same plot about a week later 90 0. beatus, 26 0. formosanus and 

 100 Mymarids. 



During 1921 the infestation has been light, and observations show 

 that heavier infestations occur in fields of 6-12 months' growth, where 

 the difficulties of artificial control are increased. 



Smith (L. B.). Breeding Mosaic Resistant Spinach and Notes on 



Malnutrition. — Virginia Truck Expt. Sta., Norfolk, Bulls. 31 and 



32, April- July 1920, pp. 137-160, 5 figs., 5 tables. TReceived 



11th November 1921.] 



The chief agents in the transmission of the mosaic disease of spinach 



are Macrosiphum solanifolii (pink and green aphis) and Myzus 



persicae (green peach or spinach aphis). Parthenogenetic generations 



of these species occur throughout the year and may cause severe loss 



to crops. They can be controlled by spraying on spinach that is 



harvested before 1st December, but this is not practicable in the case 



of late crops. At present no other remedial measures are known. 



Experiments prove that the Manchurian spinach is distasteful to these 



Aphids, and that they are less abundant on the hybrid stock than 



on the commercial strains of Savoy spinach. 



Smith (L. B.) & Zimmerley (H. H.). Relation of Pressure to Effec- 

 tiveness in Spraying Tomatoes. — Virginia Truck Expt. Sta., 

 Norfolk, Bulls. 33 and 34, October 1920-January 1921, pp. 163- 

 190, 10 figs., 8 tables. [Received 11th November 1921.] 



For many years the authors have endeavoured to devise a practical 

 spraying scheme for the control of insect and fungus pests of tomatos, 

 which are one of the chief crops in Virginia. One of the most serious 

 pests is Heliothis (Chloridea) obsolcta, Hbn. The adult moths emerge 

 in early May and deposit eggs on the plants, which are in full bloom 

 between 15th May and 1st June. The larvae begin to feed when 

 the earliest fruit is set, eating through the skin into the pulp. These 

 punctures also permit the entrance of fungi. 



The spraying experiments undertaken in 1919 and 1920 on the 

 early crops are detailed. In 1919 the average percentage of infestation 

 on plots sprayed with lead arsenate and Bordeaux mixture at pressures 

 of 200, 140 and 75 lb. was 16-25 per cent., 16-51 per cent, and 16-81 

 per cent, respectively, while on unsprayed plots it was 25-23 per cent. 

 In 1920, spraying at pressures of 200, 140 and 75 lb. showed infestation 

 of 11-70 per cent., 14-24 per cent, and 15-12 per cent, respectively, 

 unsprayed plots showing 21-39 per cent. 



CooLEY (R. a.). Department of Entomology. — 27th Ann. Rept. 

 {1919-20) Montana Agric. Expt. Sta., Bozeman, February 1921, 

 pp. 27-29. [Received 12th November 1921.] 



One of the chief pests in Montana is the pale western cutworm 

 [Porosagrotis orthogonia], which caused over ^^600,000 worth of damage 



