67 



with death those not joining in the ceremony, and then as a further mark of degradation 

 "bury them in a different place, all together in one hole. 



Of all the Hymenoptera beneficial to the farmer, none bear comparison with the 

 several species of parasitic ichneumon flies, which lay their eggs in the bodies of other 



insects, in which the grubs live, and from the 

 juices of whose bodies they derive their nour- 

 ishment ; it is curious, too, that these unbidden 

 guests avoid most carefully all the vital parts 

 of their hosts, and frequently the larvae, with 

 their strange inhabitants, change into pupae 

 before the parasites are evolved. These flies 

 are, as a rule, very characteristic in appearance, 

 and thus easily recognized. Fig. 51 represents 

 one of these parasites (Macroceptrus delicatus), 

 with its long delicate sting, which attacks the 

 codling moth. For the most part they bear a 

 very long ovipositor, with which they insert 

 their eggs into the bodies of the insects which 

 are to form their nursery. The abdomen of 

 this family presents an almost endless variety 

 of forms, w^hich are adapted to the requirements 

 of its (Siief use, viz. : the support of the organs 

 of reproduction. In Pelecinus polycerator, the 

 scorpion fly, the abdomen of the female is long 

 and slender, w^hile that of the male is short and 

 club-shaped. In Rhyssa lunator, the hand- 

 somest of all our ichneumons, the ovipositor of 

 the female produced to the extraordinary length 

 of between three and four inches. It may 

 frequently be found dead upon trees, securely 

 fastened there by this organ, which it has been 

 unable to withdraw after having deposited an egg in the body of some larva lying hidden 

 beneath the bark. The genus Ichneumon proper is one of very great extent and use- 

 fulness. Two of its species are very common, and have been found to be the chief 

 checks upon the multiplication of the dreaded Army Worm (Leucania unipuncta). Figs. 

 52 and 53 show the Army Worm in both the larval and perfect conditions. These two 



Fig. 51. 



Fig. 52. Fig. 53. 



beneficial insects are I. sitturalis and /. paratus. It is probably safe to say that there is 

 no insect which is safe from the attacks of the ichneumons, and this statement also holds 

 good even with regard to themselves. 



To the genus aphidius belong several minute species which destroy the different kinds 

 of plant lice. 



There are even some which are parasitic upon the eggs of other insects, and which are 

 so small that a magnifying glass is required to distinguish their forms. 



Among the Chalcididae are some exceedingly interesting insects. All are of small 

 size and usually of shiny colours. The small species of parasitical Hymenoptera are par- 

 ticularly useful to man as checking many of the injurious species of Diptera, which from 



