120 INSECT ARTIZANS AND THEIR WORK 



but as the carpenter's gimlet. This beetle (Try- 

 fian&us) differs from most of its congeners in being 

 cylindrical. Its object is to tap the burrows of 

 other wood borers and eat them in their retreats. 

 He says, " They drill holes into solid wood, and 

 look like tiny animated gimlets when at work, their 

 pointed heads being fixed in the wood, whilst their 

 smooth, glossy bodies work rapidly round, so as to 

 create little streams of sawdust from the holes." 



But enough of these carpenter beetles ; we must 

 glance at a few moths whose caterpillars have 

 adopted this industry as a livelihood. First of 

 these, on account of its superior size, is the larva 

 of the Goat Moth (Trypanus cossus), which ordinarily 

 attains a length of four inches, with a thickness of 

 half an inch. It spends three years boring tunnels 

 into the heart of sound trees, including poplar, 

 willow, oak, elm, and ash. So vigorous a tree as 

 an oak may take several generations of Goat cater- 

 pillars to kill, but when the tree is dead the cater- 

 pillars are said to leave it. Before each winter it 

 hollows out a space in its tunnel, and spins a com- 

 fortable temporary cocoon in which it lies inactive 

 during the cold weather. 



When full-fed it leaves its burrow, and seeks 

 about for light loose material in which to spin its 

 final cocoon. This may be in some rotten wood 

 of the tree whose hard parts it has been eating, 

 but as a" rule it has to wander away to find what 

 it wants. At such times (in autumn) one may find 

 them wandering about roads. On one occasion, in 



