90 



These analyses do not, however, give any real insight into the 

 significance of the altered cUmatic conditions, and the author, after 

 reviewing the work of other writers on this question, points out that 

 a solution of these problems can be arrived at only by further 

 investigations. 



Tragardh (Ivar). Undersokningar over gran- och tallkottarnes 

 skadeinsekter. [Investigations on the Insects injurious to Spruce 

 and Pine Cones.] — Meddelande fran Statens Skogsforsoksanstalt, 

 Stockholm, 1917, Hafte 13-14, pp. 1141-1404, cxxxvii-cxlvi, 44 figs. 

 English Summary. [Received 16th February 1917.] 



In this paper, which forms the introductory portion of the investiga- 

 tions, only the most common of the injurious insects which are found 

 on spruce cones collected during the winter and their parasites are 

 dealt with. The investigations were based on about 14,000 cones 

 collected from different parts of Sweden and kept in breeding cages of 

 the so-called American type. 



Cydia {Laspeyresia) strobilella, L., occurs all over the country. The 

 parasites of this moth previously known were : — Nemeritis cremastoides, 

 Holm., Ephialtes glabratus, Ratz., and Bracon anthracinus, Nees (?). 

 To this number the author w^as able to add only one species, Epiurus 

 geniculatus, Kby. Of these parasites Nemeritis cremastmdes is 

 distributed all over the country and occurs in 78 per cent, of the 

 locahties, in many of which it attacked more than 20 per cent, of the 

 larvae. Ephialtes glabratus seems to be far less common, occurring in 

 only 25 per cent, of the locahties, in only one of which did parasitism 

 reach more than 20 per cent., while in 73 per cent, of the localities in 

 which it occurred only 5 per cent, of the caterpillars were attacked. 

 Bracon sp., formerly referred to as B. anthracinus, is not yet definitely 

 identified, though it is closely allied to that species. It is common 

 all over the country, having been found in 67 per cent, of the localities. 

 The importance of these species is considerably increased by the fact 

 that they occur together and in many localities more than 39 per cent, 

 of the caterpillars was parasitised by one or the other of them. Epiurus 

 geniculatus is very rare, having been found only in three localities. 

 It seems likely that it is in reality a parasite of Dioryctria [Phycis) 

 abietella and has only occasionally been present in the cones because 

 its host was killed before it had time to leave them. 



The spruce-seed midge, Perrisia strobi, Winn., was bred from cones 

 as long ago as 1848, but nothing was known regarding the feeding 

 habits of the larva. In 1895 Nitsche found the larvae of a gall midge 

 in spruce seeds, but failed to breed them, and in Germany no further 

 attempts seem to have been made to solve this problem [see however 

 this Review, Ser. A, vi, p. 5]. In Finland Sahlberg in 1890 bred a gall 

 midge from spruce seeds which he identified with P. strobi. The fact 

 that investigators on the one hand found larvae in the seed, which they 

 failed to breed, and on the other found cocoons in the scales from which 

 gall midges emerged, gave rise to the view that two different species 

 occm-red. This, however, is not the case ; the larvae feed in the seeds, 

 leaving these before pupation and entering the scales, where they form 

 the characteristic white cocoons. These cocoons are easily found on 

 cutting a cone in two ; they are flask-shaped, rounded at the bottom 

 and tapering towards the mouth, which corresponds to an irregular 



