Fig. 485.—Egg-capsule of Periplaneta americana: a, side; b, end view; c, natural size.—After Howard and Marlatt, Bull. 4, Div. Ent. U. S. Dept. Agr.
The oötheca of the cockroach (Fig. 485) is a solid, dense case, which, after being carried about by the mother, can be left without harm in the crevices of the floors of houses. The oötheca of Mantis (Fig. 486) is formed by a large mass of frothy matter, which hardens and is attached to stems of plants.
Fig. 486.—Egg-capsules of Mantis carolina.—After Riley.
On the other hand, the female “walking-stick” (Diapheromera femoratum) drops her eggs, says Riley, loosely upon the ground, from whatever height she may happen to be, and “one hears a constant pattering, not unlike drops of rain, that results from the abundant dropping of these eggs, which, in places, lay so thick among and under the dead leaves that they may be scraped up in great quantities.” (Report for 1879.)
The eggs of the lace-winged flies are supported on pedicels, above the reach of ovivorous mites.
The female Chrysopa usually lays between 40 and 50 eggs. In one case, we observed that 18 egg-stalks were deposited, but there were only nine well-formed eggs in the batch, and nine eggless stalks, some only half the usual height, others with the knob of cement at the end to which the egg is ordinarily fastened. The eggs are evidently stuck on to the end of the pedicel after the latter has been formed, as, in one instance, an egg was glued to the stalk very much out of centre, the insect’s abdomen not having been aimed straight, so to speak, at the mass of cement.
Fig. 487.—Eggs of Chrysopa, with larva and fly.