The majority of insects hatch from eggs

The majority of insects hatch from eggs. The fertilization and development takes place inside the egg, enclosed by a shell (chorion). Some species of insects, like the cockroach Blaptica dubia, aswell as juvenile aphids and tsetse flies, are ovoviviparous. The eggs of ovoviviparous animals develop entirely inside the female, and then hatch immediately upon being laid.[7] Some other species, suchas those in the genus of cockroaches known as Diploptera, are viviparous, and thus gestate inside the mother and are born alive.[9]:129, 131, 134–135 Some insects, like parasitic wasps, showpolyembryony, where a single fertilized egg divides into many and in some cases thousands of separate embryos.[9]:136–137

The different forms of the male (top) and female (bottom) tussock moth Orgyiarecens is an example of sexual dimorphism in insects.
Other developmental and reproductive variations include haplodiploidy, polymorphism, paedomorphosis or peramorphosis, sexual dimorphism,parthenogenesis and more rarely hermaphroditism.[9]:143 In haplodiploidy, which is a type of sex-determination system, the offspring's sex is determined by the number of sets of chromosomes an individual receives.This system is typical in bees and wasps.[23] Polymorphism is the where a species may have different morphs or forms, as in the oblong winged katydid, which has four different varieties: green, pink,and yellow or tan. Some insects may retain phenotypes that are normally only seen in juveniles; this is called paedomorphosis. In peramorphosis, an opposite sort of phenomenon, insects take onpreviously unseen traits after they have matured into adults. Many insects display sexual dimorphism, in which males and females have notably different appearances, such as the moth Orgyia recens as anexemplar of sexual dimorphism in insects.
Some insects use parthenogenesis, a process in which the female can reproduce and give birth without having the eggs fertilized by a male. Many aphids undergo...