Current issue: 54(4)
In a locality in Southern Finland where the white-backed woodpecker, Dendrocopos leucotos (Bechst.), was previously breeding was found many conical borings excavated during the winter in young aspens (Populus tremula L.) on average 8.1 cm in diameter. Full-grown larvae of Saperda carcharias (L.) (Coleoptera, Cerambycidae) hibernated in pupal chambers constructed about 0.5 m above ground level. Below this chamber the larva has usually prepared an exit hole. After the larva has blocked itself in the pupating chamber it is easy to prey for the woodpecker during the whole winter.
There were usually 1–5 conical borings in the same trunk. The number of these borings did not correspond with the amounts of larvae eaten, since the woodpecker often made these borings in places from which it could not obtain a prey. The woodpeckers stopped excavating in those cases when the larvae in the galleries were dead. The exit holes and the conical borings occluded within a few years. The galleries within the tree will not heal and several years later a new larva may utilize them. In the wintering habitats of the white-backed woodpecker the availability of food could be improved by increasing the amount of S. sarcharias larvae. This is easily done by encouraging young aspens.
The PDF includes a summary in Finnish.
Hybrid aspen (Populus tremula L. x Populus tremuloides Michx.) has been grown in Finland for about 20 years, and the area of the stands is currently about 400 ha. Growing is planned to be greatly expanded to grow raw material for match industry. The aim of this investigation was to study susceptibility of hybrid aspen to insect damages. Insect damages in hybrid aspen, growing in Southern Finland, were examined in 15 stands in 1972. Saperda species were observed to be the most numerous and harmful insect species. Saperda carcharias L. occurred in 26% and Saperda populnea L. in 36% off trees inspected. Mass occurrence of Chionaspis salicis L. was observed in some sample areas.