23; SKOGSENTOMOLOGISKA BIDRAG II 423 



juries caused by it must not be underestimated. The mode of oviposition, 

 the tunnels and the pupal chambers (fig. 8 & 9) are of the same type as 

 those of P. pini only smaller. The weevil has been found from Scania in 

 the South of Sweden to Norrbotten in the North. It attacks chiefly the crown 

 of the pine-trees but may also on smaller trees occur on the greater part of 

 the trunk. The importance of P. piniphilus is evident from the following 

 analyzes of dying or dead trees graphically drawn in figs. 10 — 12. In all 

 instances this pine weevil started the attack, in some cases, however, following 

 on Peridermium. In most instances JLvelophilus piniperda followed in the next 

 year in the lower part of the trunk, but when the attack of the pine-weevil 

 was very severe, as in no. 9 Table I, Hyhirgops palliatus succeded in the follo- 

 wing year. Sometimes Pissodes pini started attacking in the same year as P. 

 piniphilus, but in the lower part of the trunk (no. 3 table II and fig. 12), 

 and in some cases Carphoborus Cholodkovskvi succeded in the year following 

 upon the attack of the pine beetle (fig. 11 and no. 1, 4 and 5 table II). 



3. Orchestes testaccus Mull. 

 The adult, the larva and the pupa are delineated in figs. 13, 14 and 15 

 resp. The larva makes mines in the leaves of birch (fig. 16) and ålder (fig. 

 17). The oviposition takes place in the middle vein of the leaf, the larva 

 making at first a narrow tunnel towards the margin of the leaf, but subse- 

 quently excavating the mine into a blotch-mine in which låter on the circular 

 cocoon is conspicuous through its black colour. When the leaves are small 

 (fig. 16) the first narrow part of the mine is swallowed by the blotch-mine 

 causing the observer wrongly to believe that there is only a blotch-mine. Lo- 

 cally outbreaks of this species have been observed by the author, when al- 

 most all leaves were attacked. 



4. Trichogramma evancscens Westw an egg-parasite of Lyda [Cephaleia) signa/a Y. 



During an outbreak of Lyda signa/a at Dalby in the South of Sweden, this 

 parasite was bred from the Lrda-eggs. An minute comparison of the material 

 in mv position with Oophthora semblidis Auriv. of which species material was 

 put to my disposal by the courtesy of professor Y. Sjöstedt of the Museum 

 of Natural History, Stockholm and of specimens bred from eggs oi Are tia caja 

 by dr. F. Nordström failed to show any differences between them, and an 

 examination of the drawings of Trichogramma piniperda made by YVolff also 

 failed to reveal any distinguishing characteristics. My opinion that T. evanescens 

 Westw. is widely distributed and has many different hösts was subsequently 

 confirmed both by mr. Krvger of Copenhague, the wellknown authority on 

 Trichogammina. and by mr. J. Waterston, of the Brittish Museum. 



A compilation of the hösts of T. evanescens (s. 17) goes to show that it is 

 one of the most polyphagons egg-parasites hitherto recorded, with a list of 

 not less than 30 different species recorded (not to speak of all species not 

 recorded\ In Dalby the egg-parasite during several summers played an im- 

 portant part, in 19 19 killing about 90?/ of the eggs of the spruce saw-fly. 

 During the following years, as a consequence, the saw-fly was rather scarce 

 but in 1923 it increased in number again and this time the climatic con- 

 ditions were not favourable to the propagation of the parasite which in this 

 year only killed about 5 % of the eggs. 



