192 TRANSFORMATIONS OF INSECTS. 
twelfth of an inch long. They have no less than eighteen joints 
in their antennz, and they deposit a quantity of eggs inside many 
species of caterpillars. 
After having lived in the juices of the caterpillars, the larve 
of the Muicrogasters having attained their full growth, begin to 
devour the viscera also, and finally they eat through the skin. 
They then spin silky cocoons, and undergo their metamorphosis. 
One of the species, JZtcrogaster glomeratus, which is black in colour, 
and which has fawn coloured legs, can be recognised easily, and its 
metamorphosis examined. The caterpillars of the cabbage butter- 
fly, Pueris brassice, are frequently killed by this little parasite, 
and occasionally nearly every one of these destructive vegetable 
feeders falls a prey. They usually live until about the time of the 
first metamorphosis, and then they begin to look out for a safe 
place to hang themselves up, and to undergo the transformation 
into the chrysalis state. But it is just then that they die, for then 
the Microgasters which have had enough of the caterpillar, pierce 
through its skin, and form their cocoons on and around it. They 
complete their metamorphosis in a few days, and the perfect para- 
sites fly. The cocoons of these JJicrogasters are usually united 
in packets, are oval shaped, and being composed of very fine 
yellow silk, look like those of silkworms in miniature. The 
smallest of the ichneumons are the species of the genus H/ydrizon, 
and they wage war against the Affides, one of them laying its 
egg in the Apfzs, which is so common on the delicate stems of 
roses. 
The Proctotrupide are distinguished from the /chneumonide 
by their oblong body, the simple condition of the nervures of the 
wing, the moderately long antenne, and the long pendant palps. 
They are such little insects that they must be examined with a 
good lens or a microscope, if they are to be studied. One tribe of 
them attacks the maggots of flies, especially of the wheat fly, and 
another lays its eggs in the larve of the 77zpw/e@—the daddy long- 
legs tribe. Some of the parasites of the maggots spin cocoons 
beneath the skins of their victims. The TZeleas ovulorum is a tiny 
insect of about a fiftieth of an inch long, and it lays its eggs in 
the eggs of moths, and when its larvee are developed they enjoy 
their curious and small habitation. 
