PARASITISM 



881 



FIG. 373. Larva of the Catalpa sphinx moth frdm which are issuing the larva* 

 of ichneumon flies. The Avhite ovoid bodies are the cocoons in which the 

 larvae transform to adults. Over a hundred parasites were present in this host. 

 Photograph about life size. 



butterflies collected in late summer or autumn nearly one 

 half will usually be found to contain the parasites of 

 either the ichneumon or chalcis flies. 



The chalcis flies are small, and some species deposit 

 their eggs on the skin instead of within the insect, and 



FIG. 374. Thalessa, an ichneumon inserting its two-inch ovipositor in a beech tree 

 to lay an egg in the burrow of the horn tail, a wood borer upon which the young 

 ichneumon will feed. The two curved hairlike supports steady the ovipositor. 

 Photograph. 



