its search the _Chrysis_ deposits several eggs—from six to ten; for some reason that is not apparent all but one of these eggs fail to produce young; in two or three days this one hatches, the others shrivelling up. The young _Chrysis_ larva seizes with its mouth a fold of the skin of the helpless larva of the _Odynerus_, and sucks it without inflicting any visible wound. In about eleven days the _Chrysis_ has changed its skin four times, has consumed all the larva and is full-fed; it spins its own cocoon inside that of its victim, and remains therein till the following spring, when it changes to a pupa, and in less than three weeks {4}thereafter emerges a perfect _Chrysis_ of the most brilliant colour, and if it be a female indefatigable in activity. It is remarkable that the larva of _Chrysis_ is so much like that of _Odynerus_ that the two can only be distinguished externally by the colour, the _Odynerus_ being yellow and the _Chrysis_ white; but this is only one of the many cases in which host and parasite are extremely similar to the eye. _Chrysis shanghaiensis_ has been reared from the cocoons of a Lepidopterous Insect—_Monema flavescens_, family Limacodidae—and it has been presumed that it eats the larva therein contained. All other Chrysids, so far as known, live at the expense of Hymenoptera (usually, as we have seen, actually consuming their bodies), and it is not impossible that _C. shanghaiensis_ really lives on a Hymenopterous parasite in the cocoon of the Lepidopteron. _Parnopes carnea_ frequents the nests of _Bembex rostrata_, a solitary wasp that has the unusual habit of bringing from time to time a supply of food to its young larva; for this purpose it has to open the nest in which its young is enclosed, and the _Parnopes_ takes advantage of this habit by entering the cell and depositing there an egg which produces a larva that devours that of the _Bembex_. The species of the anomalous genus _Cleptes_ live, it is believed, at the expense of Tenthredinidae, and in all probability oviposit in their cocoons which are placed in the earth. SERIES 3. HYMENOPTERA ACULEATA. _The females (whether workers or true females) provided with a sting: trochanters usually undivided (monotrochous). Usually the antennae of the males with thirteen, of the females with twelve, joints (exceptions in ants numerous)._