6o 



INSECTS 



between the prothorax and the rest of the body, and 

 their habit of snapping or springing up with a jerk 

 when turned on their backs. The wire-worms gain 

 their name from the tough leathery texture combined 

 with a slender wormlike form and most of them feed 

 underground, devouring the roots of many sorts of 

 plants, severely injuring or actually destroying such 

 as they attack. But there is also a large contingent 

 that lives in woody tissue — nearly always dead tissue 

 and quite generally such as is well advanced in decay. 

 The insects can scarcely be 

 called borers, because they are 

 hardly fitted to make their way 

 in sound wood ; but in logs and 

 stumps or even dead standing 

 trunks they are often found in 

 goodly numbers. 



Typical wood-borers are 

 found among the BuprestidcB, 

 which are usually metallic, hard- 

 shelled beetles, generally of good 

 size, often with handsomely sculptured wing-covers. In 

 the larval stage these are known as flat-headed borers 

 or "hammer-heads" because, immediately behind the 

 mouth structures the first thoracic segment is much en- 

 larged and often chitinized, giving the appearance of a 

 very broad, flattened head, followed by a long slender 

 body in which all the joints are well marked. These bor- 

 ers work in the bast and sap-wood of the trunks and 

 branches of trees and shrubs, making shallow galleries of 

 more or less characteristic shape and sometimes enor- 

 mous length. A single borer not over an inch and a 

 quarter long, may make a gallery an eighth of an inch 

 wide and over ten feet in length, leaving a trail of dead 

 tissue that the tree in many cases cannot replace or mend. 



Fig. 20.— Click-beetle and wire 

 worm from side and top. 



