THE HYMENOPTERA 



353 



parasites laying many eggs regularly attack only those species of insects 

 large enough to provide for the progeny, while those which lay only one 

 egg in or on a host require all the food provided there for the single 

 parasite. No case is known where a parasite normally laying many eggs 

 in a host will select a smaller one and deposit only one or a few in it. 



FIG. 368. Hawk-moth larva with cocoons of parasites which have fed upon it, on its back. 

 (From Felt, N. Y. State Mus. Mem. 8.) 



Variations in the location of the pupa also occur. Some parasites 

 pupate within the body of the host; others on its surface (Fig. 368) while 

 still others leave the insect entirely, pupating singly or in groups, away 

 from it. Tomato worms and other large caterpillars are often seen in 

 the fall, either dead or dying, and with many small, white, oval bodies 

 on their backs. These are cases where the numerous parasites after 

 having completed feeding within the body of the host, have come out and 

 pupated on its back, the white bodies being the cocoons of the parasites. 



Superfamily Chrysidoidea (The Cuckoo Wasps). This is a rather 

 small group of the Hymenoptera, the insects (Fig. 369) being seldom over- 

 half an inch in length and generally considerably 

 smaller. Their bodies are green, of a metallic or 

 bluish shade which quickly distinguishes them 

 from certain of the bees which are also green 

 but brighter. The surface of the body is gen- 

 erally closely covered with fine indentations 

 which give it a roughened appearance. 



These insects are able to sting but no poison 

 gland seems to be present. The abdomen which 

 has only a few (three to five) visible segments, is flat beneath, and 

 when attacked the insect can roll itself into a ball for protection. 



The Chrysids are parasitic, chiefly on wasps and bees, though a 

 few are claimed to attack saw-flies and one is a parasite on the Oriental 

 Moth. The parent Chrysid watches its opportunity to visit the nest of 

 its host and lays an egg in a cell with that of the host. On hatching 



23 



FIG. 369. Cuckoo Wasp 



(Chrysididae) , somewhat 

 enlarged. (From Bischoff.) 



