HYMENOPTERA. 
23 
black, with reddish legs, the wings being better furnished with nervures than in other 
members of the family. In the chrysalis-stinger ( Pteromalus puparu/m) the egg 
is laid in the chrysalis of several common butterflies during summer, while the 
larvae remain in their host all through the winter, sometimes to the number of fifty. 
1, gouty-legged wasp ; 2, chrysalis-stinger ; 3, Sketches of various Chalcididce (enlarged). 
The Ichneumox-Wasps,— Family I ciinaumonid^e. 
The species included in this vast family number upwards of six thousand, and 
doubtless more remain to be discovered. The majority are parasitic on the larvae 
of Lepidoptera, rendering good service to the agriculturist and gardener by holding 
in check the enormous quantities of larvae hatched every year. Some, however, 
attack other insects as well as spiders. The family is distinguished by the 
variation of the wings, though these characters vary too slightly to be of much 
value for generic or specific purposes. The antennae are of uniform thickness, 
many-jointed, and, as a rule, filiform, though in some exceptional cases club-shaped. 
The ichneumon-wasps do not hum, either when quiescent or on the wing, and are 
thus enabled to approach the victim within whose body they wish to lay their 
eggs with a greater chance of success. Having selected a suitable caterpillar, 
the female deposits an egg with her ovipositor either on or beneath its skin. The 
egg soon hatches, and the grubs feed upon the tissues of the larvae until full fed, 
when they pupate in or around the now almost empty skin of the caterpillar. The 
family has been divided into five groups, sufficiently distinguished from each other 
in their typical forms, but merging into one another through transitional species. 
Our first example is the ichneumon ( Exenterus marginatorius ) figured in the 
illustration on p. 24, which belongs to the subfamily Tryphonince, and is 
found chiefly in pine-woods, where it is parasitic on Lophyrus pini, described on 
p. 16. The female attaches an egg by means of a booklet to the skin of the green 
larva3, when nearly full grown. When the insect forms its barrel-shaped pupa, in 
which to pass the winter, the parasite remains attached to the skin of the larva, 
whose tissues it gradually absorbs. The perfect insect makes a small hole in the 
pupa-case when it emerges, and does not, as does L. pini, bite off a little cap at 
the top. Another type is Bassus albosignatus, which frequents the honey-dew 
dropped by aphid colonies. It lays its eggs on various larvae which feed upon the 
