38 NEW ZEALAND ENTOMOLOGY. 



introduce their eggs into their hosts, 1 is not at present 

 known to entomologists, but it seems at least probable 

 that they are deposited in the eggs of the parasitic Dip- 

 teron before these gain access to the caterpillar of the 

 moth. 



Family ICHNEUMONID.E. 



Ichneumon sollicitorius (Plate III., fig. 6). 



This is the most abundant of our ichneumon-flies, and 

 may be taken amongst herbage from August till May. Its 

 larva is parasitic in the caterpillars of various Noctuae, 

 having occurred in the following species : Mamesna 

 composita, M. mutans, and M. ustistriga. The pupa may 

 be frequently discovered inside that of the moth, and is 

 quite white in its early stages, but as age advances all the 

 colours of the future insect can be seen through the thin 

 pellicle which invests it. The perfect insect makes its 

 escape through a circular hole, which it drills in the upper 

 end of the unfortunate moth pupa it has destroyed. The 

 sexes of all ichneumon-flies may be at once recognized by 

 the females possessing an ovipositor 2 differing consider- 

 ably in length among the various species, but nearly 

 always plainly visible. 



Family ICHNEUMONID^:. 

 Ichneumon deceptus (Plate III., fig. 7). 



This conspicuous insect is chiefly mentioned on account 

 of a very curious habit possessed by the females of con- 

 gregating in large numbers on matai trees, as many as fifty 

 or sixty specimens being often found huddled together 

 under a single flake of the bark. The males are occasion- 

 ally taken flying in the open, but I have never seen any 

 amongst these large assemblages of females. Whether the 



1 " Host " is a term applied to any animal harbouring a parasite. 



2 Ovipositor, a boring instrument employed in depositing the eggs. 



