420 



of this forest are virgin, but the greater part shows traces of human 

 action of slight importance, such as the removal of dead wood. The 

 chief differences between normal German forests and this area are 

 its enormous extent — about 320,000 acres, the mixture of many 

 varieties of trees, the absence of clearings and plantations, the 

 untouched soil-covering and the marshy character of extensive tracts. 



As regards insect infestation it was found that prmiary pests were 

 not common. Injury to leaves and needles was rare ; for instance very 

 few spruce showed traces of [Eucosma] tedella or other Tortricids. 

 Still rarer were such Hymenoptera as Lyda,Lophyrus and Nematus, and 

 the Coleoptera, Brachyderes, Strophosomus, Phyllobius, etc. Only a 

 few oaks were badly infested by the oak miner, Tinea complanella. 

 Galls were not numerous ; in one case galls of Chermes were abundant 

 on a spruce covered with PhysoJaermes piceae. In spite of the number 

 of oaks, oak-galls were very rare, only one type, those of the C}Tiipid, 

 Neuroterus nmnismalis, being noticed. Willows and poplars also were 

 almost free from galls ; in one instance those of Pontania salicis were 

 seen on Salix purpurea. The leaf-galls of Eriosoma {Schizoneura) uhni 

 occurred on elms in the grounds of Bialowies castle. The absence of 

 injury by Hylobius to the root-crowns of spruce and pine was remark- 

 able. Of the more harmful Lepidoptera the nun moth [Lipa7-is 

 monachal alone seems to find conditions favourable to an occasional 

 outbreak. 



In striking contrast was the remarkable abundance of secondar}^ 

 pests. The chief of these are Scolytid, Buprestid and Cerambycid 

 beetles, which predominate over all others. Among the Cerambycid ae 

 were Prionus coriarius, Leptura rubra, L. dubia, Monochanius sartor, 

 M. galloprovincialis, Necydales uhni, Saperda perforata, Clytanthvs 

 varius, Acanthoderes davipes, Acanihocinus griseus, Liopns nebulosus, 

 etc. The Buprestids included Buprestis rustica, B. maculata, B. hae- 

 morrhoidalis and Pliaenops cyanea, all four of which were seen together 

 in large numbers on one occasion. The number of Scolytid beetles, 

 however, greatly exceeded those of the above two families. One pine 

 trunk harboured Myelophihis piniperda, M. minor, Ips {Toniicus) 

 sexdentatus and /. (T.) laricis, besides Buprestids and Cerambycids, and 

 this appeared to be the general rule. Of the bark-beetles of conifers 

 /. (T.) laricis was the most frec[uently met with, other species found in 

 abundance being /. [T.) typographus, I. {T.) amitinns, M. piniperda, 

 M. minor, Pityogenes bidentatus, P. quadridens, P. chalcographus and 

 Polygraphus poligraphus. Hylastes ater, H. opacus, H. palliatus and 

 Dryocoetes autograjjhus were fairly common and a few specimens of 

 Ips {Tornicus) suturalis, I. {T.) dnjjlicatus, I. {T.) JongicoUis and 

 Polygraphus subopacvs were found. Compared with species breeding 

 in the bark the timber-infesting beetles were few in number, only a few 

 specimens of Xyloterus lineatus being observed in fallen or standing 

 dead conifers. The bark-breeding genus Pissodes was almost com- 

 pletely absent, and no adult individuals were seen, though a few mines 

 of P. piniphilus and some pupae of P. notatus were observed, (r: iWiti - 



Secondary pests were of common occurrence in the case of deciduous 

 trees also, Scolytiis ratzeburgi was particularly abundant in birch and 

 in many situations it appeared to be a prmiary pest. Xyloterus 

 signatns was also often noticed in birch. Poplars and aspens were 

 sometimes severely infested with secondary enemies ; in one case a 



