112 BRITISH INSECTS 



or no cruelty or acute suffering connected with this 

 mode of life. The victim attacked is not eaten, the 

 parasites in the interior taking in the lymph of the cater- 

 pillar either by the mouth or by endosmosis (i.e., through 

 the skin), but not biting their host. The latter displays 

 no sign of sickness, but eats voraciously, so that it serves 

 merely as a sort of intermediary between the juices of 

 the plant and the larvae inside itself. 



The families Chalcidida and Pvoctotvypidcz comprise 

 enormous numbers of tiny Hymenoptera. They are 

 so diminutive that they are rarely noticed, save by the 

 few entomologists who make them their special study. 

 Nevertheless, they are of the utmost importance to 

 agriculturists, since many of the species are very de- 

 structive to field and garden pests. On the whole, 

 their habits resemble those of the ichneumons, but 

 their range of attack is much wider. Some of the 

 Chalcids, for instance, oviposit in aphides, one egg 

 being inserted into each victim. Many of the Procto- 

 trypidcB are egg-parasites. They lay their eggs in 

 those of larger insects, and in some instances half a 

 dozen or more parasite grubs find sufficient nutriment 

 for their development in a single moth's egg a fact 

 which bears eloquent testimony to the extreme minute- 

 ness of the adult insect. Among the smallest species 

 of all are some that enter the water in order to lay 

 their eggs in those of dragon -flies. 



The pretty ruby -wasps l are noted for their brilliant 

 metallic hues blue, green, and crimson. They lay 

 their eggs in the nests of bees and wasps, and their 

 grubs were formerly believed to feed as " cuckoo 

 parasites," eating up the food stored for the benefit 

 of the rightful occupants of the nest ; but there is now 

 1 Chrysididce. 



