COLEOPTERA. 123 



vary its intensity at pleasure. This faculty of emitting 

 light is one of the most puzzling circumstances in their 

 history, nor is it easy to conjecture what end it serves. 

 The suggestion frequently advanced, that its purpose is 

 to guide the winged male to the apterous female in the 

 darkness of the night, is by no means a satisfactory ex- 

 planation : for, besides the fact that other nocturnal 

 insects need no such aid, in many species of the genus 

 both sexes are luminous, and both furnished with wings. 

 The light of these foreign species (as for example, the 

 lucciole of Italy and the fire-flies of North America) far 

 surpasses the feeble glimmer of our own, and when the 

 air is filled with myriads of them intersecting each other's 

 path in every direction, the scene is one of indescribable 

 beauty 



The Death Watches (Ptinus)* are a race of small in- 

 sects, often formidable on account of the ravages they 

 commit upon our property. Many species of this genus 

 inhabit the interior of our houses, 

 where, in their larva condition, they 

 cause much damage by boring into 

 wood. Nothing of a vegetable nature 

 comes amiss to them planks, rafters, 

 beams, chairs, and tables, and even 

 books, all fall a prey to their hungry 

 industry ; they bore them through and 

 through with holes as sharply cut as if 

 they had been drilled with the finest 

 instruments. Some devote their special 

 energies to farinaceous substances, and devour the very 

 wafers in our desks : others, more formidable still to the 

 naturalist, attack our collections of birds and insects, and 

 commit sad havoc in our museums. 



In some species both sexes, by way of calling their 

 mates, are in the habit of rapping sharply and quickly 

 with their mandibles upon the wood that they frequent, 

 and replying* to each other in the same manner. The 

 noise thus produced, which somewhat resembles the tick- 

 ing of a watch, has gained for them, from the ignorant and 

 superstitious, the name of the " Death-watch," by which 

 they are familiarly known. 



The fourth section of Coleopterous Pentamerans 



* iTTt)v6s, ptenos, winged. 



G 2 



