Parasitic Insects 



Parasites. — ^In addition to the insects that hunt 

 garden pests, there are many others that feed inside 

 them or in their eggs. These parasites belong to 

 various families of insects, but the most familiar are 

 the ichneumons. They are easily recognised by the 

 abdomen being attached to the body by a thin stalk, 

 by the long egg-laying apparatus projecting from 

 the end of the body, by which they penetrate the 

 body of their prey, and by their long quivering 

 antennae. The variety of these ichneumons is very 

 great, for most caterpillars are subject to the attacks 

 of one or more species of ichneumon, and generally 

 each species of parasite is confined to one species of 

 host, while many of the parasites are themselves 

 subject to the attack of other parasites. 



The eggs of the parasite are laid either in the egg 

 of the host or in the body of the larva. The grubs 

 that hatch from these eggs may pass their whole 

 life in the egg of their host, finding sufficient susten- 

 ance to secure f uU development therein ; others feed 

 in the body of the larvae until that is full-grown 

 without damaging any vital part. Some emerge 

 from it while still in the larval stage, others not 

 until it has assumed the chrysalis stage. The 

 masses of cocoons of one ichneumon are familiar to 

 every grower of cabbages. The caterpillars of the 

 cabbage-white butterfiy are parasitised by it, and 

 when they are fuU-fed the parasites eat their way 

 out through the skin, spin cocoons, and become 



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