Wasps, Bees, and Ants 
477 
classification, together with their (mostly) small size and the slight and 
hardly recognizable differences on which their scientific distinction rests, 
would make their systematic study nearly impossible for the amateur. On 
the other hand the interesting character and the biologic and economic 
importance of their habits of life make it desirable to know as much as may 
be about their life-history. I shall, therefore, give the little space which our 
book can afford to these insects almost exclusively to a consideration of the 
ecologic aspects of their study. 
Fig. 670.—Hairy caterpillar killed by parasitic ichneumon-flies which have left the 
body through small holes in the skin. (Natural size.) 
The superfamilies and families meant to be included among the insects 
referred to when the general term “parasitic Hymenoptera” is used are 
(using Ashmead’s classification) the 
superfamily Proctotrypoidea, a great 
group of mostly minute species, many 
of which pass all their immature life 
within the eggs of other insects; the 
superfamily Chalcidoidea, an even 
larger group, also of small species, 
but with a few forms which are gall- 
makers and not parasites; and the 
superfamily Ichneumonoidea, including 
the larger parasitic Hymenoptera. 
Each of these superfamilies includes a 
number of families, and the three 
together comprise an enormous host 
of mostly little-known insect species. 
At the present time much diversity 
exists in the arrangement of the various 
parasitic families in entomological 
manuals. In the older books the para¬ 
sitic habit has been looked to as in¬ 
dicating an affinity of relationship 
among them all; in more recent books 
and papers is adopted an arrangement 
proposed by Ashmead which indicates ; 
Fig. 671.—Caterpillar killed by Hymen- 
opterous parasites which have issued 
from the cocoons attached to the skin 
of the caterpillar; upper figure one of 
the adult parasites. (After Jordan and 
Kellogg; caterpillar and cocoons natu¬ 
ral size; adult parasite much enlarged.) 
nearer relationship on the part of 
