immature insects rick story, department of entomology

Immature Insects

Rick Story, Department of Entomology

Types of Insect Development

1)Incomplete (egg nymph or larva adult)

2)Complete (egg larva pupa adult)

Insect Growth

-external skeleton

-grows with successive molts

-each stage is an instar

-typically 5-7 instars for larval growth

Insect Metamorphosis

-change in body form from immature

to adult stage

Incomplete Metamorphosis

Immatures look like adults except:

1)Smaller

2)Lack wings

3)Lack genitalia

Incomplete Metamorphosis

Immatures look like adults:

1)Same mouthparts

2)Feed on same plants

3)Occur together with adults

4)Have compound eyes

Complete Metamorphosis

-immatures do not look like adults

-have an inactive pupal stage for transformation

Complete Metamorphosis

Immatures unlike adults:

1)Different mouthparts

2)Different host plants

3)Do not typically occur together

4)Lack compound eyes

Identification of Immatures

Incomplete development orders – characterssimilar for nymphs and adults

Complete development orders- characterscompletely different

Main orders with complete development

Neuroptera : green + brown lacewings

Lepidoptera : caterpillars (moths)

Hymenoptera : sawfly larvae, ants, bees, wasps

Diptera : maggots (flies)

Coleoptera : white grubs, weevils, wireworms (beetles)

Neuroptera

-Larvae are predators, with well developed legs and an elongated body

-sickle shaped mandibles with blood groove diagnostic character

Lepidoptera

-Larvae (caterpillars) are plant feeding and have chewing mouthparts

-caterpillar body form diagnostic (cylindrical body, thoracic legs well developed, abdominal prolegs present)

Diptera

-Larvae with variable feeding habits and chewing mouthparts

-body with head capsule partially to completely reduced, no thoracic legs, soft bodied, white, often occur in damp habitats.

Coleoptera

-Larvae with chewing mouthparts, plant feeding or predators

-Have well developed head capsule, thoracic legs present (usually), and lack abdominal legs

Hymenoptera

-sawflies: caterpillar body form (prolegs lack hooks), feed on foliage

-bees, wasps, ants: grub-like body form with well developed head capsule and no thoracic legs.

Author: Rick Story

rstory@agcenter.lsu.edu