Members of genera Nectophrynoides and Eleutherodactylus bear froglets, not only the hatching, but all the most conspicuous metamorphosis, being completed inside the body of the mother before birth.
Among insects that depend on opportunistic exploitation of transient food sources, such as many Sarcophagidae and other carrion flies, and species such as many Calliphoridae, that rely on fresh dung, and parasitoids such as tachinid flies that depend on entering the host as soon as possible, the embryos commonly develop to the first larval instar inside the mother's reproductive tract, and they hatch just before being laid or almost immediately afterwards.
Other species exhibit matrotrophy, in which the embryo exhausts its yolk supply early in gestation and the mother provides additional nutrition.
Modes of reproduction include[3] based on relations between zygote and parents: Some insects, notably tachinid flies, are ovolarviparous, which means that the embryos develop into the first larval stage (instar) within the eggs while still in the female's oviduct.
A similar phenomenon is larviparity, in which larvae hatch before the female delivers them, although this may be mistakenly identified in species with very thin and transparent egg membranes.