90 OENERA OF HYMENOPTERA. 



combined, slender, cylindrical at base, gradually widened towards the 

 apex, the second and following segments becoming gradually shorter 

 to a|)ex. 



The females are common where they occur, while the males are 

 exceedingly rare. Their habits are unknown, but are doubtless 

 parasitic. 



TUBULIFERA 



This group of insects contains the single family Chrysididae, char- 

 acterized by the abdomen having apjiarently very few segments, 

 from three to five, the remainder being modified into a telescopic and 

 retractile tube, which is drawn within the body when not required 

 for its legitimate purjjose ; it is furnished at the extremity in the 

 males with the organs of generation and in the females with a minute 

 sting-like ovipositor. 



These insects, although of niodeiate size, are among the most 

 beautiful of our hymenoptera, being adorned with brilliant metallic 

 blue, green and ruby. The body is often deeply punctured, the ab- 

 domen in some genera being almost rounded or semicircular and 

 entire at apex, while in other genera, e. g. Ckrysis, it is usually ter- 

 minated by a series of teeth, varying in number from two to six, the 

 apical margin being preceded by a transverse row of deep pits. 



In their economy the Chrysidida; are said to differ from the pre- 

 ceding tribe in that the females do not deposit their eggs in the bodies 

 of other insects, but cuckoo-like, place them in the already provis- 

 ioned nests of other hymenoptera, chiefly those of solitary wasps and 

 bees, and being first hatched, these larvae feed upon and devour the 

 supply of food stored up for the support of the others, which are 

 thus starved and destroyed. 



Family CHRYSIDIDiE. 



The following synoptic table is compiled from an excellent mono- 

 graph of the family by Mr. S. F. Aaron, jjublished in the I'ith vol- 

 ume of these Transactions and illustrated by several plates of well 

 drawn figures, leaving the compiler little or nothing to do but to 

 copy the characters given of the subfamilies and genera. 



The family is divisible into four subfamilies, as follows : 



