Types of Eggs Laid in Groups

Egg Laying

• Eggs can be laid in groups, with different species exhibiting unique characteristics
• Pedicellate eggs are laid on plants in silken stalks, around 1.25 mm in length (e.g., green lacewing)
• Barrel-shaped eggs are deposited in compact masses (e.g., stink bug)
• Ootheca is a brown, chitinous capsule containing eggs, laid by cockroaches
• Egg pods are formed by grasshoppers, which secrete a frothy material that encases the eggs
• Egg cases or oothecae are formed by mantids, which deposit eggs on twigs in a foamy secretion called spumaline
• Egg masses are laid by moths, with eggs stuck together with body hairs (e.g., rice stem borer)
• Egg rafts are formed by Culex mosquitoes, consisting of 200-300 eggs laid in water

Larval Stage

• The larval stage is the active growing stage, differing radically from the adult stage
• There are four main types of insect larvae: protopod, oligopod, polypod, and apodous
• Protopod larvae have little yolk, and abdominal segmentation is absent (e.g., endoparasitic Hymenoptera)
• Oligopod larvae have thoracic legs and are further divided into campodeiform and scarabaeiform types
• Polypod or eruciform larvae have three pairs of thoracic legs and up to five pairs of unjointed abdominal legs or prolegs (e.g., caterpillars)
• Apodous larvae are without legs (e.g., house fly larvae)

Nymphs and Metamorphosis

• Nymphs are young ones of lower orders, resembling adults except for wings and reproductive organs
• Larvae are young ones of higher orders, differing from adults in appearance and growth
• There are three types of metamorphosis: ametabola, hemimetabola, and holometabola
• Ametabola have no metamorphosis, with little external change during growth (e.g., silverfish)
• Hemimetabola have gradual or incomplete metamorphosis, with immature forms called nymphs (e.g., grasshoppers, bugs)
• Holometabola have complex or complete metamorphosis, with immature forms called larvae (e.g., butterflies, beetles)

Pupal Stage

• The pupal stage is the resting and inactive stage in all holometabolous insects
• During this stage, the insect is incapable of feeding and is quiescent
• There are three main types of pupae: obtect, exarate, and others
• Obtect pupae have appendages glued to the body, with exposed surfaces heavily sclerotized (e.g., moth pupa)
• Exarate pupae have free appendages, with the pupa soft and pale (e.g., rhinoceros beetle pupa)