SEP - 7 1914 



Division of Forestry 

 University of California 



INJURIES TO FORESTS AND FOREST PRODUCTS BY 

 ROUNDHEADED BORERS. 



By J. L. WEBB, 

 Agent and Expert, Forest Insect Investigations, Bureau of Entomology. 



FOREST INSECT DEPREDATIONS. 



In recent years much stress has been laid upon the conservation of 

 natural resources in the United States. Of these resources, the forests 

 have probably absorbed more attention than any other. Vast areas 

 have been set aside from the public domain as National Forests in 

 order that the timber supply of the country shall not become ex- 

 hausted. Much has been said on the subject of damage by fire to the 

 forests, and it is fully realized that this is an ever-present danger. 

 But a more insidious and equally relentless foe of the forests is found 

 in the form of insects which work terrible destruction, often unno- 

 ticed until the damage is done. The immense destruction to living 

 forests by certain scolytid barkbeetles, as well as the injurious work 

 of flat-headed borers, have been given attention in former Yearbook 

 articles. In this article another group containing many injurious 

 species is discussed, namely, roundheaded borers. The information 

 conveyed in this paper is based almost entirely on the material and 

 records of the forest insect collection of the Bureau of Entomology. 



ROUNDHEADED BORERS. 



Roundheaded borers are so called to distinguish them from the 

 flat-headed borers. 1 The general appearance is that of an elongate, 

 fleshy, yellowish-white grub, sometimes bearing three pairs of legs 

 and sometimes without legs. The head is more or less oval in shape, 

 though sometimes elongate, and often deeply retracted within the 

 first prothoracic segment, which is situated immediately behind the 

 head. The head is provided with a strong pair of jaws or mandibles, 

 >rown or black in color, for cutting through plant tissue. Some spe- 

 cies mine only in the bark of trees, some mine in both bark and 

 wood, and some confine themselves to herbaceous plants. In each 

 case the borer is hatched from an egg laid upon or in the bark or 



1 See " Injuries to forest trees by flat-headed borers," Yearbook, 1909, p. 399. 



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