May. I9IO. The hish Naiiiralisf. 89 



THE ECONOMIC IMPORTANCE OF SCOLYTIDAE 



IN IRISH FORESTRY. 



by a. c. forbes. 

 [Plate 2.] 



Although no particular group of insects can be regarded as 

 .strictly confined to forest trees in their use of feeding or breed- 

 ing material, the family of the Scolytidae, perhaps, occupies 

 such a position more nearly than any other. Of several 

 hundred species enumerated by Eichhoff^ as indigenous to 

 Europe, only some half dozen feed on other than trees or 

 woody plants, the remainder almost entirely confining their 

 operations to the wood or bast layers of their hosts, and rareh' 

 being seen on the surface except at pairing time. For this 

 reason they have probably escaped the notice of the ordinary 

 collector to some extent, unless he may have made a special 

 stud\' of tree pests, or been brought into close contact with 

 felled timber. In fact, a saw-miller of an entomological 

 turn of mind would possibly see more of this family in a year 

 than the professional entomologist in a life-time, and they are 

 brought more prominenth' to the notice of the practical 

 forester than hundreds of genera of greater importance from a 

 cultural stand-point. 



In economic entomology it is customary to regard this 

 family as injurious. A close acquaintance with any typical 

 species, however, must lead one to the conclusion that this 

 adjective is scarcely correct when applied coUectiveh' to the 

 whole of the genera comprised in it. With one or two 

 exceptions the}- should rather be regarded as natural scavengers 

 performing similar functions to those of saprophytes amongst 

 fungi, and by hastening the decay of dead material assisting 

 the econoni}' of nature to a very great extent. The fact that 

 the}^ are often found in dying or dead trees may be partly 

 responsible for the idea that they have brought about the 

 destruction of their host ; but so far as the writers observations 

 have gone, no health}^ tree is ever attacked by anj^ species, 

 except in such of its parts or branches as have finished 

 their work, or are more or less immaterial to the existence of 

 the plant. 



It is the purpose of this note to mention a few species of 

 bark beetles which may, under certain exceptional circum- 



' " Die Europaischen Borkenkafer. "' 



