The Ichneumon Flies 



Life History of an Ichneumon Fly 



(Pimpla inquisitor, Say.^ 



« 



This important but widespread parasite of caterpillars 



occurs in California, Texas, Iowa, Illinois, Missouri, Ohio, New 

 York, New Hampshire, Massachusetts, Virginia, District of 

 Columbia, and is probably to be found in all parts of the United 



Fig. 38. — Pimpla inquisitor ; a, b, c, larvae at left ; e, male abdomen. 

 ( Author^s illustration.) 



States except possibly in the very coldest portions. It is para- 

 sitic upon a large number of different kinds of larvae of moths 

 feeding upon such concealed spinners as the tent caterpillar of 

 the orchard and the army worm of the forest (Clisiocampa 

 americana and C. disstria) and upon certain stalk borers and gall 

 makers, leaf folders and certain of the larger leaf miners. It is by 

 far the most abundant of the parasites of the white marked tus- 

 sock moth (Orgyia leucostigma), a famous shade tree enemy of 

 the northeastern United States. The adult Pimpla is shiny black 

 in color and has a wing spread of, on the average, three-quarters 

 of an inch, the length of its body being about one-half an inch, 

 but it varies greatly in size, the adults issuing from well fed larvae 

 exceeding these measurements and under-fed specimens trans- 

 forming into much smaller adults. Upon the tussock moth 

 caterpillar and upon the army worm of the forest the female 

 Pimpla will lay her eggs when the larvae are full grown or just after 



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