Fig. 650.—Development of Platygaster: A, stalked egg: a central cell giving origin to the embryo. B, g, germ; b, blastoderm cells. C, the same, farther advanced. D, cyclops-like embryo: md, rudiments of mandibles; d, rudimentary pad-like organs, seen more developed in E; st, bilobed tail.
The second stage, or Histriobdella-like form, as Ganin names it, is more like that leech-like worm than an insect.
The third larval form is very bizarre, though more as in insects, having rudimentary antennæ, mouth-parts, legs, and ovipositor. In this condition it lives from six to seven days before pupating (Fig. 653).
The strange history of another egg-parasite (Ophioneurus) agrees in some respects with that of the foregoing forms. It is when hatched of an oval shape, with scarcely any organs, and differs from the genera already mentioned in remaining within its egg-membrane, and not assuming their strange shapes. From the cylindrical sac-like non-segmented larva resembling the second larva of Platygaster it passes directly into the pupa state.
A fourth form, Teleas (Fig. 654, A-D), is an egg-parasite of Gerris, and in America one species oviposits in the eggs of Œcanthus.
Fig. 651.—First larva of Platygaster: m, mouth; at, rudimentary antenna; md, mandibles; d, tongue-like appendages.
Fig. 652.—Second larva of Platygaster: œ, œsophagus; ng, brain; n, nervous cord; ga and g, genital organs; ms, muscular band.