Common spruce sawfly
| Common spruce sawfly | ||||||||||||
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| Cephalcia abietis | ||||||||||||
| ( Linnaeus , 1758) |
The common spruce sawfly ( Cephalcia abietis ) is a plant wasp from the family of the spruce sawfly (Pamphiliidae).
features
The genus Cephalcia comprises 12 species in Europe, of which all but two Nordic species occur in Central Europe; the species are difficult to distinguish from one another. The animals are 11 to 14 millimeters long, have a black head and thorax with yellow spots. The abdomen is red-yellow with a black base.
Cephalcia abietis has a broader, more robust abdomen than most other species of the genus with the exception of Cephalcia alashanica , the females can be distinguished from this species by the color of the clypeus (in C. abietis marginally without yellow sections), in the male by the color of the Abdomen sternites three to five (monochrome yellow-brown, in C. alashanica the front half is black). In addition, the temporal pits in the female are further removed from the edge of the eye. Further features to distinguish it from related species: the wing membrane of the females clearly clouded brown, but without a separate brown band, vertex of the males without yellow color markings.
The larvae are initially gray-green, green to golden yellow after the last moult and are about 20 millimeters in length.
Occurrence
The common spruce gall wasp occurs in central and northern Europe and in Siberia , eastwards to northern China. In Central Europe it prefers forests in the mountain regions, in the lowlands the related species Cephalcia arvensis is more common.
Way of life
The species lives in spruce forests. The main food crop in Europe is the Norway spruce , to the east there are also other spruce species ( Picea koraiensis , Picea jezoensis , Picea obovata ). Almost only older (one to three year old) needles are eaten; Buds and fresh needles are usually spared. However, there are indications that the May shoot is occasionally eaten (e.g. in Thuringia), which can then threaten the survival of the tree. The species is said to prefer young spruce over older trees, but occurs on spruces up to around 120 years old. The needles are eroded at the base and then eaten under the protection of the web.
In contrast to the lazy females, the males are active flyers. The females usually climb up the trunks after hatching in the ground. They are not very active in flight and attract the males with pheromones .
development
The females lay their eggs from April to June in small groups of 4 to 12 on the needles of the previous year. In total, a female lays around 80 to 120 eggs. The young larvae form groups that create a common web in which they live and eat, with each larva inhabiting its own tube within the web. The web is interspersed with excrement particles. The last larval stage drops to the ground in late August to early September and then burrows. Pupation takes place 5 to 25 centimeters deep in the ground in a cave without web. It often happens that the animals are two to five years old before the adults hatch. Adults can be found from around the beginning of May to the end of June.
Occasionally there are mass reproductions of this type, in which the trees can be devoured. Densities of up to 400 pupae per square meter of forest floor can be achieved. Although large numbers of pupae are dug up and eaten by wild boar during the mass infestation, the infestation cannot be effectively limited as it does not reach those in deeper soil layers. Webbing can occur on more than three quarters of the branches during such a mass increase and merge sideways into one another.
In forestry , the species is usually considered to be a minor pest. The trees rarely die, only the growth is reduced and the susceptibility to other pests increases. In the following year, the trees usually drive out later and / or caring. The control is usually carried out by spraying insecticides, for example Dimilin . The control of the species is made more difficult by the overlying animals in the soil, which cannot be controlled with chemical means.
Individual evidence
- ^ Andreas Taeger, Stephan M. Blank, Andrew D. Liston: European Sawflies (Hymenoptera: Symphyta) - A Species Checklist for the Countries. In: SM Blank, S. Schmidt & A. Taeger (editors) (2006): Recent Sawfly Research: Synthesis and Prospects. Goecke & Evers, Keltern - ISBN 3-937783-19-9
- ^ A b C van Achterberg & B. van Aartsen (1986): The European Pamphilidae (Hymenoptera: Symphyta) with special reference to The Netherlands. Zoological Negotiations Leiden 234: 1-98.
- ↑ A. Battisti & J.-h. Sun (1996): A survey of the spruce web-spinning sawflies of the genus Cephalcia Panzer in north-eastern China, with a guide to the identification of prepupae (Hym., Pamphiliidae). Journal of Applied Entomology 120: 275-280. doi : 10.1111 / j.1439-0418.1996.tb01606.x
- ↑ Andreas Taeger, Ewald Altenhofer, Stephan M. Blank, Ewald Jansen, Manfred Kraus, Hubert Pschorn-Walcher, Carsten Ritzau Comments on the biology, distribution and endangerment of the plant wasps in Germany (Hymenoptera, Symphyta). In: Taeger, A .; Blank, SM (1998) (Ed.): Plant wasps in Germany (Hymenoptera, Symphyta). Annotated inventory. - Goecke & Evers, Keltern, 364 + 3 pp.
- ↑ a b Ulf Baier & Lutz-Florian Otto (2000): Studies on the Great Spruce Leaf Wasp Cephalcia abietis L. Contributions to forest protection research in Thuringia. Notices from the State Institute for Forests and Forestry Issue 17/2000: 47-68.
- ↑ Hannes Lemme: The spruce wasp is currently raving about it. Focus on forest protection; Bayerische Waldschutz-Nachrichten No. 7, May 19, 2009. Published by: Bavarian State Institute for Forests and Forestry, Section Forest Protection.
- ↑ LWF: Characteristics of the Spruce Leaf Wasp ( Memento of the original from October 29, 2013 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. .
Web links
- Cephalcia abietis L. - Common spruce sawfly ( Memento from July 5, 2008 in the Internet Archive )