THE INSECT WORLD. 



381 



when hatched, crawls along the burrow until it comes into contact 

 with its host. It then punctures the skin and remains fixed to 

 the outside, sucking the juices and gradually killing the borer. 



Fig. 438. 



Pimpla conquisitor . — a, larva ; c, pupa ; d, adult ; other references are to structural 



details. 



By no means all of our "ichneumons," even of those belong- 

 ing to the family IcJmeumonidcB , have external ovipositors ; yet 

 there is a distinctive character in their appearance which is easily 

 recognized but hard to de- 

 scribe. The species belong- 439- 

 ing to the typical genus Ich- 

 neumon have rather long, 

 slender forms, with flattened 

 abdomen and no external 

 ovipositor. They are often 

 gaudily colored, the antennae 

 are frequently banded with 

 yellow, and many are metallic 

 blue or green. The species 

 are usually parasites on cater- 

 pillars. One of the largest 

 and most frequently noted species is that which infests the larvae 

 of the common swallow-tail" butterflies. It is orange-yellow 

 in color, with smoky-black wings, the body nearly an inch in 



Tragus exesorius on a chrysalis of Papilio, 

 from which it has emerged. 



