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HoLSTE (G.). Fichtenzapf en- iind Fichtensamenbewohner Oberbayems. 



[Insects inhabiting Spruce Cones and Spruce Seed in Upper 

 Bavaria.] — Zcitschr. angew. Ent., Berlin, viii, no. 1, September 

 1921, pp. 125-160, 15 figs. 



These investigations were begun in 1919, having been suggested by 

 Tragardh's paper on the pests of spruce and pine cones [R.A.E., 

 A, vi, 90]. 



The injurious species may be divided into pests of seeds and pests 

 of cones. 



As regards the pests of the seed very httle can be added to Seitner's 

 results on Plemeliella ahietina, Seitn. (spruce-seed gall-midge). The 

 author found the larvae of P. ahietina only within the spruce seed, 

 or — in a few instances — working their way out of the seed that had 

 been husked. Pupation usually occurs within the seed, and in the 

 open is comparatively rare, but is possible in the case of fully mature 

 larvae that have been removed from seeds. Tragardh erroneously 

 referred larvae of Plemeliella, which he did not recognise as such, 

 to the early larval stage of Perrisia strobi. P. ahietina seems to occur 

 everywhere in Upper Bavaria, and as many as 68 larvae have been 

 found in a single cone. They appear to be more sensitive to dryness 

 than their parasite, Torynms azureus. Boh., for a sample of seed kept 

 quite dry up to 21st January 1920 yielded no midges, while two 

 specimens of T. azureus appeared in May. 



The larvae of the Chalcid, Megastigmus abietis, Seitn., were obtained 

 in several batches of seed. Feeding was found to be over by March 

 and April, the seeds being then quite empty, only a portion of the 

 skin being left. This is characteristic of M. ahietis, and does not occur 

 in the case of P. ahietina. The larva described by Tragardh as that 

 of Torymus azureus^ Boh., is certainly that of M. abietis. 



A beetle, Ernohius ahietis, F., is a common pest of spruce cones 

 and seeds. The statement of previous authors that the female 

 oviposits on cones on the trees appears to be correct, as fallen cones 

 were not infested in the breeding experiments. Destruction of the 

 seeds by E. ahietis is probably chiefly due to the young larvae ; six 

 per cent, of one batch of seeds was damaged by this beetle. 



The pests of cones comprise three different groups : those that 

 abandon the cones in autumn before they fall ; those that reach the 

 ground in the fallen cones and complete their development in them ; 

 and those that probably infest cones that have already fallen, completing 

 their development there. 



Dioryctria abietella, Schiff., is the sole representative of the first 

 group. As the cones examined were collected in winter and early 

 spring, no living stages were taken of this moth, which is on the wing 

 in July. The traces of infestation showed it to be generally distributed 

 in Upper Bavaria. Quite a number of cones that had been infested 

 remained on the trees instead of falling in autumn. 



The second group embraces Ernobins abietis, already dealt with, 

 Perrisia strobi, Winn., Camptoniyia strohi, Kieff., and Cydia [Las- 

 peyresia) strohilella, L. P. strohi (spruce-cone-scale gall-midge) has 

 been constantly confused with Plemeliella ahietina (spruce-seed gall- 

 midge), and even Tragardh came to incorrect conclusions on this point. 

 His minute description of the developmental stages and of the adults 

 of Perrisia strobi satisfy all requirements if it is borne in mind that 

 the larva in the spruce seeds is that of Plemeliella ahietina. This 

 discovery of the author's is confirmed by Seitner, who states, in a letter 



