450 



In experimenrs conducted by the Government Experiment Station 

 the measures that proved effective against the larvae of Pieris included 

 Dufour's mixture (6 lb. soap, 3 lb. insect powder in 20 gals, water) and 

 dusting with insect powder and lime (1 : 4) or tobacco dust. 



Hammarlund (C). Blandade Besprutningsvatskor for samtidigt 



Bekampande av Skorv och Skadeinsekter pa Appletrad. [Mixed 



Sprays against Fungi and Insects on Apple Trees.] — Meddelande 



fran Centrahnstalten for Fdrsdksvdsendet pa J ordhruksomrddet, 



Stockholm, no. 134, Botaiska avdel. no. 12, 18 pp., 4 figs., 1916. 



The results are given of a series of experiments with mixed sprays 



carried out in the years 1914-1915 against the fungus, Venturica 



dendritica, and the moths, Cijdia (Carpocapsa) pomonella, L., and 



Argyresthia conjiigeUa, Z., the object being to find a combination which 



could be used simultaneously against both fungi and insects. 



The following mixtures were tried : lead arsenate and Bordeaux 

 mixture, copper arsenate and Bordeaux mixture, lead arsenate and 

 lime-sulphur, and copper arsenate and lime-sulphur. It was found 

 that the percentage of fruit infested by C. pomonella and A. conjugella 

 was reduced from 7-65% to 2-3% on the sprayed trees, the lowest 

 percentage arrived at being 1'18 when the trees had been sprayed with 

 lead arsenate and Bordeaux mixture on the first of June and on the 7th 

 of July. The author is however of opinion that the general infestation 

 was too small for any positive conclusions to be arrived at. 



Nielsen (J. C.) Tachin-Studier [Tachinid Studies]. — Videnskabelige 

 Meddel., Co2JenJiagen, Ixix, 1918, pp. 247-262. 

 This paper contains a review of the author's investigations on the 

 biology of the Tachinids, especially as regards their relation to their 

 hosts and their life-cycle. The geographical distribution of these 

 parasitic flies may be smaller than that of the host, e.g., Carcelia gnava 

 a parasite of Stilpnotia salicis. The opposite also occurs, and a given 

 species of Tachinid may be dependant on different hosts in various 

 parts of the world, e.g., Rhacodineura antiqua, parasitic in Russia on 

 Forficula tomis and in western Europe on F. auricularia. The hosts to 

 which a given Tachinid is adapted are in some cases only few species 

 or those within a single genus, e.g., Exorista hlepharipoda, which is 

 only^ found in larvae of Acronycta. Others will only infest insects 

 within a single family, e.g., Viviania cinerea, only attacking Carabids. 

 Many Tachinids can however be reared from insects quite different 

 from their principal host, e.g., Pelatachina from larvae of Vanessa, as 

 well as from those of Folia (Mamestra) oleracea. Most Tachinids 

 are polyphagous and can, for instance, attack Tenthredinid or 

 Chrysomelid larvae as well Lepidopterous ones. Tachinid eggs may 

 sometimes be found on unsuitable hosts. The suitability of a 

 given host is not connected with its systematic position but with 

 external conditions, e.g., the tender larvae of Tachina mella, though 

 normally parasitising Lepidopterous larvae, cannot pierce the skin 

 of those of Porthetria disjjar ; or with internal ones, the body fluid of 

 certain unsuitable hosts having specific properties that have a poisonous 

 effect on the parasite. Individual larvae of the same species of 

 Tachinid living in different hosts increase in size at varying rates 



