238 NORTH AMERICAN INSECTS. 
form themselves into white silken cocoons, which resemble 
rice-seeds in appearance, and which cover the whole body 
of the emaciated and dying caterpillar. 
Very minute ichneumons, scarcely visible to the naked 
eye, deposit their eggs in the eggs of different lepidopterous 
insects, and from these the perfect ichneumon issues about 
three weeks after. 
The family of Ichneumon-wasps is immensely large in all 
parts of the world. In 1829 the Swedish entomologist, 
Gravenhorst, published three large volumes on ‘‘ Jchnewmon- 
ologia Europea,” to which Professor Nees, of Bonn, made a 
considerable addition; but if one should undertake to de- 
scribe the genera and species of the American, Asiatic, 
African, and Australian ichneumons, of all of which very 
little is known, he would occupy more than twenty large 
volumes. 
The largest ichneumon of this country is the Porpia 
Lunator (Fig. 66), the body of which is about one inch 
and a half, and the ovipositor three inches long. One 
would naturally suppose that so long an organ, with the 
two side bristles, which serve as a scabbard, would be 
very burdensome to this insect; but by watching her 
movements he would soon see with what ease and skill 
this little creature manages that instrument, and by means 
of it introduces her eggs into those larve which are con- 
cealed in deep holes under the bark of trees, or in decayed 
wood. 
We have before spoken of the handsome green caterpillar 
of the Asterias Butterfly, represented in Fig. 30, and found 
so commonly upon the leaves of all the umbelliferous plants. 
Our attempts to raise the handsome Papilio asterias from 
these caterpillars have often been frustrated by a species 
of ichneumon which, stinging the caterpillar, grows within 
its body until it forms its cocoon, when it destroys the 
chrysalis, and then emerges from the cocoon instead of the 
