92 



in Entedon. Tliis species has not been definitely proved to be the- 

 parasite of Tonjmus azureus, though very strong circumstantial 

 evidence of this exists. A. strohilanae occurs all over the country and 

 seems to surpass even Platygaster in effectiveness. While the latter 

 in 63 per cent, of the localities only killed up to 20 per cent, of Penisia, 

 the corresponding figure for Aprostocetus occurs in 30 per cent, of the 

 localities. The curves of both species fall at 50-60 per cent, infection, 

 but while the largest number of localities for Platygaster is to be found 

 where there is no parasitism, the corresponding figure for Aprostocetus 

 coincides with a parasitism of 30-40 per cent. The curve of Aprostocetus, 

 however, at the higher percentage of parasitism is very peculiar, 

 rising from 71 to 80 per cent., so that no less than 12 per cent, of the 

 localities show an infestation of 91-100 per cent. The localities 

 where there is such high percentage prove on examination to be 

 precisely those where Perrisia strobi was very numerous, while 

 Platygaster was either very scarce or did not occur at all. This seems 

 to show that some correlation exists between these facts. The larvae 

 of Perrisia and Torymus both live in the seeds of the spruce and 

 consequently compete for the same food-supply. The data of bred 

 individuals show that the former appears earlier than the latter, and 

 there is no reason to suppose that this succession is altered under natural 

 conditions. Hence, if a high percentage of the seeds are attacked by 

 Perrisia the possibility of Torymus finding a sufficient supj)ly of seeds 

 decreases, and its number is reduced. At the same time the increase 

 of Platygaster contorticornis, the normal parasite of Perrisia, has been 

 checked, presumably owing to climatic conditions. When therefore, 

 Aprostocetus appears, it finds a large number of seeds attacked by 

 Perrisia larvae that are not parasitised, and only a few Torymus, and 

 in consequence it is forced to attack the former instead of the latter. 



Kemner (N. a.). Gulhariga skinnarbaggen {Blitophaga opaca L.) — 

 Centralanstaltenfor Jordbruksforsok, Flygblad no. 62, June 1916; 

 Entomologiska Avdelningen, no. 15, 4 pp., 2 figs. [Received 

 14th February 1918.] 



This SUphid beetle has repeatedly injured sugar-beet, potatoes and 

 barley in Sweden. The adults hibernate in the ground under stones 

 and moss and are markedly nocturnal in their habits, being very 

 sluggish during daytime and, when disturbed, dropping to the ground 

 and hiding themselves under stones. The eggs are deposited in the 

 ground with the aid of the ovipositor and covered with earth. The 

 larvae are full-grown in about three weeks and pupate in the soil, the 

 adults emerging after about a fortnight. There is only one generation 

 a year. This beetle occurs all over Sweden, attacking sugar-beet in 

 the south and barley in the north. Suggested remedies are sprajdng 

 with lead arsenate and rolhng the ground. 



Kemner (N. A.). Artvivein {Sitona lineatus L.) — Centralanstalten for 

 Jordbruksforsok, Flygblad no. 63, June 1917; Entomologiska 

 Avdelningen, Stockholm, 1917, no. 16, 4 pp., 5 figs. [Received 

 14th February 1918.] 



This paper contains a short description of the biology of Sitones 

 {Sitona) lineatus and the remedies employed to deal with it. The 



