606 



This parasite does not appear to attack more than one larva, and 

 three or four days after destroying its host it pupates in the rape 

 pod witliout making a cocoon. The pupal stage lasts 8-10 days. 



Kleine (R). Wie lasst sich der Frass von GrapJwlitha dorsana 

 vermeiden ? [How is Injury by Cydia dorsana to be avoided?] 

 — ZeitscJir. angew. Ent., Berlin, viii, no. 1, September 1921, 

 pp. 112-118. 



Peas are an important crop in Gemiany, but are liable to severe 

 infestation by Cydia {Grapliolitha) dorsana. Different varieties of 

 pea vary in their demands on the soil, and a variety grown in unsuit- 

 able soil is weak and much exposed to attack. Even on good soil 

 infestation may be severe if rainfall and temperature are unfavourable. 

 General weather conditions are the chief factor, and a dry year favours 

 C. dorsana. 



This moth is on the wing in May and June, and the larva appears in 

 June and July. 



It is very important that the crop should remain dry. In 1919 

 rain fell on 25th and 26th July during the harvest, and the peas mowed 

 after the rain were attacked, whilst those cut previously were not 

 infested. This shows that the age of the pea is immaterial, and that 

 a fully mature seed is attacked if it contains or reabsorbs sufficient 

 water. 



Mixed sowing is the one successful method of combating infestation, 

 and several years' observations show the advantage of a mixed 

 crop of oats and peas. Experimentally they were sown in equal 

 proportions, but the author believes that the proportion of pea 

 seed should not exceed one-third. The object is to have the peas 

 always protected b}^ the other plants, which should not be oats alone ; 

 barley, at least, should be added. Further experiments may show if 

 other Leguminosae could be included in a mixed crop. 



Herrmann ( — ). Arsensalze zur Bekampfung des Apfelwicklers 



[Carpocapsa pomonella, L.). [Arsenic Salts against Cydia ponion- 

 ella.] — Zeitschr. angeiv. Ent., Berlin, viii, no. 1, September 1921, 

 pp. 119-124. 



Cydia {Carpocapsa) pomonella, L., is one of the worst fruit pests 

 in Germany, and in spite of restrictive legislation, arsenical insecticides 

 are being increasingly employed against it. 



To test the value of arsenicals under German conditions experiments 

 were begun in 1914 and continued in 1919 and 1920, with the following 

 salts : Paris green containing 58 per cent, of arsenious acid and com- 

 mercially known as Urania green ; a lead arsenate containing 32-9 

 per cent, of arsenic acid ; and " Zabulon," a lead arsenate containing 

 arsenic acid. Spraying was done immediateh' after blossoming and 

 was repeated 3-4 weeks later. 



In 1914 spraying decreased the loss in fallen fruit by more than one- 

 half. In 1919, 26-9 per cent, of the fruit on unsprayed trees was 

 infested, 18-7 per cent, on trees sprayed with Urania green, and 

 15-8 per cent, on trees sprayed with the lead arsenate containing 

 32-9 per cent, of arsenic acid. In 1920 these two salts gave equally 

 good results, while " Zabulon " proved somewhat less efhcacious. 



