288 iNJCTKiotrs insects 



optera. This order includes the parasitic Ichneumon- 

 flies, which range all the way from flies an inch or more 

 in length, to minute species scarcely visible to the naked 

 eye. The larger kinds deposit only one egg in each 

 victim, while some of the smaller leave their entire com- 

 plement of eggs on one caterpillar. A well-known 

 example, which is familiar to most gardeners, may be 

 found in the Tomato-worm. A small, black, microgas- 

 ter fly goes peering about among the tomato- vines until 

 it espies a worm, on which it lays its eggs. These soon 

 hatch, and the tiny larvas eat their way into the worm, 

 and are soon thickly packed between the skin and vital 

 organs, where they eat all the substance that would 

 otherwise go to make the future moth, and their pres- 

 ence does not prevent the worm from eating and growing 

 until the little parasites are full-fed, when they eat their 

 way out of their host, and each stands on end and spins 

 for itself a tiny white cocoon. Sometimes these cocoons 

 are so numerous that the back of the worm is almost 

 entirely covered with them, and now it shrivels and rap- 

 idly shrinks in size and soon dies. (See page 88. ) And 

 this work of destruction is constantly going on all around 

 us. Were it not for these parasites, vegetation could 

 scarcely exist on the earth. 



The great service of these Ichneumon-flies has long 

 been known, but are orchard ists and gardeners aware of 

 the untold numbers of noxious insects that a colonv of 

 White-faced Hornets (see fig. 169) will destroy in a 

 season ? They are somewhat troublesome friends, it is 

 true — hasty and hot-tempered, as one is pretty sure to 

 learn if he ventures too near their dwelling, and their 

 tempers have not been improved by coming in contact 

 with mankind, for have not their great paper nests ever 

 been a target for boys until they have inherited a dispo- 

 sition hostile to us, and which can scarcely be overcome 

 by the most gentle and kind treatment on our part ? But 



