Immature Stages of Mantidae
Detailed information on immature stages of Mantidae is being acquired. However, Clausen (1940) noted that eggs are laid in large packets, containing in some species up to 300-400 eggs, but usually less than 100, on twigs, grass stems, etc. They are laid in rows, standing almost vertically, and are enveloped in a frothy mass which soon hardens into a tough, spongy case. Several hours may be required for the deposition of a single mass. The form of the egg mass is distinctive, being almost spherical in some species, but ranging to the slender mass of Stagmatoptera septentrionalis S. & Z. Of Panama, which is 6 cm. Or more long and only 3 mm. In diam., tapering to a fine thread 1.5 cm. Long, which gives it a resemblance to a seedpod.
The young nymphs emerge from the egg mass through a series of slits left along the median line on the upper side. They molt soon after leaving the case, and the exuviae is believed to be a true skin rather than the amnion. The number of nymphal molts is not certain, 6-7 being recorded for some species and 9-10 for others. The females may pass through one or more nymphal stages than the male.
Mathur et al. (1934) gave an extended account of the biology of a series of Indian species of Mantidae. In Deiphobe sp. The hatching of the eggs in each mass covers a period of several days, in contrast to the almost simultaneous hatching that occurs in most other species of Mantidae.
Litaneutria minor Scudd. Inhabiting the more arid regions of North America, has one and probably 2 generations yearly (Roberts 1937). Fertile eggs may be laid within 2 days after mating, although this is usually at least 30 days after the adult stage is reached. Each female may lay as many as 10 masses of eggs, at intervals of ca. 10 days, each with an average of 16 eggs. Eggs that overwinter remain unhatched for 6-7 months, while those laid in early summer hatch in 30 days. There are 6-8 nymphal molts prior to the adult stage.