MORE ABOUT INSECTS 79 



until those that survive are large and strong and fierce enough 

 to face the outside world. 



Few of us I hope, no matter how sorely pressed by hunger, 

 would eat our mothers, and yet this is the fixed habit of 

 several insects. Perhaps the strangest of these is a little fly, 

 one of the gall-midges, which as a grub is found beneath the 

 bark of trees. The grubs of this gall-midge produce a number 

 of young within their own bodies which immediately proceed 

 to eat their mother, and when she is but a memory they bore 

 out of her empty skin and start life on their own account. A 

 swift retribution overtakes them, however; for young appear 

 within them and they are devoured in the same way. This 

 process of progressive mother eating continues all the winter, 

 and at the beginning of spring the now very numerous grubs 

 transform into adults. 



Large, portly and ferocious wives, bloodthirsty in dispo- 

 sition, bring to an end the happy Hves of many insect hus- 

 bands, as among the mantises where the female always eats 

 her mate; while many female spiders, much larger and much 

 more powerful than the males, seem to take a keen delight 

 in killing or maiming them. 



For all the strange habits mentioned heretofore we can see 

 a reason, though perhaps that reason seems peculiar. But 

 the metal chewing habits of some other insects are not easily 

 explained. During the Crimean war much damage was 

 done to the lead bullets used by the French army through 

 the activities of an insect larva or grub which bored holes 

 through them. This circumstance first brought into general 

 notice the fact that various insects of a number of groups 

 eat metals and other mineral substances. About twenty 

 years ago the activities of lead boring insects working on the 

 lead sheathing of aerial telephone cables in California began 

 to attract attention, and later telephone fuses, underground 

 cables, and other structures in various places, especially 

 within the tropics, were found to suffer from insect depre- 

 dations. 



