Growth & Development

Egg

	numbers vary from singles to masses of hundreds
	locations include inside plant or animal tissue, on ground, on foliage, in crevices (bark), in water, in a host (e.g. a parasite)
	some live births (flesh flies & aphids)
	termite queen can lay 10,000 eggs per day!

Growth

	immature that hatch from egg are called larva and their function is to simply eat and grow – this is usually the most damaging stage
	larva is a generic term for the immature stage of insect with complete metamorphosis (specific names include: caterpillars - butterflies/moths, grubs - beetles, maggots - flies)
	nymphs - immature stage for insects with gradual metamorphosis
	naiads - immature stage for insects with incomplete metamorphosis
	have an exoskeleton and have to molt to grow
	instar - developmental stage of a larva between molts; if an insects molts only once it is said to have 2 instars (i.e. L1 is right after hatching and L2 after the molt); many forest defoliators have 5-7 instars
	stadium - time period between molts
	insects do not molt after reaching the adult stage

Metamorphosis

	there can be significant changes in size, form and habitat between immature and adult stages; the change in form between young and adult is metamorphosis
	pupa - insect life stage when metamorphosis occurs

simple metamorphosis – 3 types

	*no metamorphosis* - very little to no change, except for size, e.g. spingtails & silverfish (this type of metamorphosis accounts for <1% of insect species)
	*gradual* - immature nymphs occupy same habitats & feed on same food, gradual change in size, proportions and gradual dev of wings & genitalia, e.g. grasshoppers, termites, aphids & true bugs (<10%)
	*incomplete* - immature emerge as naiads (=aquatic nymphs), live in water, adults are not aquatic, e.g. dragonflies, mayflies, stoneflies (<1% of insect species)

complete metamorphosis

this has the classic 4 stages: egg - larva - pupa - adult;

	eggs – sometimes the overwintering stage
	larva – their job is to eat and grow; can have several instars
	pupal stage is a non-feeding, transformation stage – this is where the change takes place between young and adult
	adults disperse and repoduce; may feed on same host, different host or not feed (live on stored fat bodies);

complete metamorphosis usually reduces competition between young & adults for food, space and shelter