This Insect provisions its cell with small caterpillars to the number of twenty or upwards (Fig. 28, A.) The egg is deposited before the nest is stocked with food; it is suspended in such a manner that the suspensory thread allows the egg to reach well down towards the bottom of the cell. The caterpillars placed as food in the nest are all curled up, each forming a ring approximately adapted to the calibre of the cell. Fabre believes these caterpillars to be partly stupefied by stinging, but the act has not been observed either by himself, Réaumur, or Dufour. The first caterpillar is eaten by the wasp-larva from its point of suspension; after this first meal has been made the larva is supposed to undergo a change of skin; it then abandons the assistance of the suspensory thread, taking up a position in the vacant chamber at the end of the cell and drawing the caterpillars to itself one by one. This arrangement permits the caterpillars to be consumed in the order in which they were placed in the cell, so that the one that is weakest on account of its longer period of starvation is first devoured. Fabre thinks all the above points are essential to the successful development of this wasp-larva, the suspension protecting the egg and the young larva from destruction by pressure or movement of the caterpillars, while the position of the larva when it leaves the thread and takes its place on the floor of the cell ensures its consuming the food in the order of introduction; besides this the caterpillars used are of a proper size and of a species the {76}individuals of which have the habit of rolling themselves up in a ring; while, as the calibre of the tube is but small, they are unable to straighten themselves and move about, so that their consumption in proper order is assured. Some interesting points in the habits of an allied species, _O._ (_Pterocheilus_) _spinipes_ have been observed by Verhoeff; the facts as regards the construction and provisioning of the cell are almost the same as in _O. reniformis_. The species of _Odynerus_ are very subject to the attacks of parasites, and are, it is well known, destroyed to an enormous extent by Chrysididae. Verhoeff says that the wasp in question supplied food much infested by entoparasites; further, that a fly, _Argyromoeba sinuata_, takes advantage of the habit of the _Odynerus_ of leaving its nest open during the process of provisioning, and deposits also an egg in the nest; the _Odynerus_ seems, however, to have no power of discovering the fact, or more probably has no knowledge of its meaning, and so concludes the work of closing the cell in the usual way; the egg of the _Argyromoeba_ hatches, and the maggot produced feeds on the caterpillars the wasp intended for its own offspring. Verhoeff observed that the egg of the wasp-larva is destroyed, but he does not know whether this was done by the mother _Argyromoeba_ or by the larva hatched from her egg.