G8 



NATURAL HISTORY OF INSECTS. 



the abdomen is generally long and slender (Figs. 39, 40, and 

 131); the ovipositor is sometimes exserted, and is frequently 

 as long and occasionally much longer than the body, (Figs. 39, 

 Fig. 185. 40. and 131). These insects are 



among the most beneficial insects 

 known, as their larvae live within 

 the bodies of caterpillars and other 

 injurious larvae (as the Bacon-fly 

 Parasite, Fig. 185, which preys 

 upon De Long's Moth) as well as in 

 the bodies of many perfect insects, 

 spiders, etc., ultimately causing 

 their death. The larvae are foot- 

 less, and usually spin cocoons wherein to undergo their trans- 

 formations. 



EGG-PARASITES (Proctotrupidae). These are minute insects, 

 with only a few veins in the wings (Fig. 186) frequently but 

 one; the antennae are sometimes elbowed; the ovipositor of 

 the female issues from the tip of the abdomen. They live in 

 their larval state within the eggs, larvae, or pupae of other 

 insects. The perfect insect seldom exceeds one twenty-eighth 

 of an inch in length. 



Fig. 186. 



BRASSLETS OB CHALCIS-FLIES (Chalcididse). These are very 

 small insects with elbowed antennae (as shown in Fig. 187), 

 and are frequently of a metallic color; the wings are usually 



