334 SYSTEMATIC ARRANGEMENT 



JOPPA PICTA. 

 PLATE XXXI. Fig. 3. 



THIS and the species delineated on the following 

 plate, afford examples of the very extensive family 

 of the Ichneumonidae, whose economy is so remark- 

 able. They deposit their eggs in the bodies of other 

 insects, particularly caterpillars, which are there 

 hatched, and the young feed on the entrails of the 

 unfortunate victim. To enable them to convey their 

 eggs into holes and fissures where caterpillars or 

 pupae often lurk, they are generally provided with a 

 long ovipositor, which is usually very slender, and 

 too weak to pierce the skin of the hand, although 

 the insects often make the attempt when seized. 

 As this weapon generally appears tripartite, these 

 insects were formerly named Muscce tripiles, and, 

 from their habit of vibrating their antennae, Muscoa 

 mbrantes. They may, in general, be known by their 

 narrow elongated form, attenuated, and, in most 

 cases, petiolated abdomen, with its hair-like appen- 

 dages behind, and long many-jointed antennae, which 

 are often recurved and annulated. The Ichneumonidse 

 are a very numerous tribe, no fewer than 1300 

 European species having been described by Graven- 

 horst in his monograph of this family, and of these 

 a large proportion occur in Britain. Our British 

 species, however, have not yet been carefully inves- 

 tigated, and it is much to be desired that some com- 

 petent observer would undertake the task. These 

 insects perform an essential service by destroying so 



