By Stephanni Perini

CLASS INSECTA By Stephanni Perini

HABITAT  Due to the wide variety of insects, they can be found in virtually any habitat around the globe  The most common habitats include aquatic and terrestrial o Aquatic (water, marsh, pond, lake, stream) . Examples of insects that could live in these habitats: mayflies, dragonflies, caddis flies, aquatic bugs, alder flies, mosquitoes o Terrestrial (desert, forest, grassland, on flowers and animals) . Examples of insects that may live in these environments: ants, springtails, proturants all live on soil. Termites, cockroaches, earwigs, silverfish and lacewings all live under rocks and in similar environments. Bees, wasps, grasshoppers, butterflies, thirps and mantids all live on and around trees and flowers.

UNIQUE CHARACTERISTICS  Lepidoptera (butterflies and moths) o 2 pairs of membranous wings covered in tiny scales that overlap o Large compound eyes with one ocelli present above each o Antennae present  long and slender in female moths, feathery in male moths, cubed in butterflies  Neuroptera (lacewings) o Elongate, soft body o 2 pairs of membranous wings of equal size o Complex wing venation with main vein forked along bottom edge o When resting, wings held like a tent over body o Long filiform antennae  Phasmatodea (stick and leaf insects) o Most body shapes elongate and cylindrical and resemble sticks, leaves and grass o Two pairs of wings although some are wingless (short hardened forewings form a protective cover) o Antennae both short and long  Hymenoptera (ants, bees, wasps) o Two pairs of membranous wings – some wingless such as types of ants o Forewings are larger than hind wings and are held together by small hooks o Females usually have a hardened ovipositor for stinging and piercing o Most have a constriction between the first two segments of the abdomen o Compound eyes  Thysanura (silverfish) o Small compound eyes- some eyeless o Long antennae o Three abdominal cerci of similar length with the two outer pointing away from the body o Soft elongate body tapering towards the abdomen and covered with silvery gray scales  Odonata (dragonflies) o Abdomen long and slender o Large compound eyes o Three ocelli o Very small antennae o Complex wing venation with many cells

FEEDING MECHANISMS  The earliest insects were said to be chewers and overtime adaptation forced them to develop feeding methods such as piercing or sucking  Chewers (Dragonflies, moth larvae, beetles, ants) o Usually have two mandibles for chewing on each side of the head o Mandibles modified per insect (cut, tear, crush, chew) o Most have a glossa which resembles a hard yet thin tongue . Beneath glossa are galea o Maxillae (below mandibles) are used to manipulate food during mastication o Palps are used to determine the characteristics of potential food  Suckers (moths, butterflies, mosquitoes, bees, wasps) o Proboscis used for piercing and then sucking . Sheathed within a modified labium to allow piercing through tissue to reach liquid o Mouthparts are elongate o Stylet formed by mandibles and maxillae and is used to pierce an animals skin o Antennae are used for feeling prey o During piercing, labium (including part of proboscis) remains outside of the skin

REPRODUCTION  There are three main types of sexual reproduction based on level of metamorphosis o Holometabolous- insect undergoes full metamorphosis (includes egg, larvae, pupae and adult) o Hemimetabolous- missing the pupae stage of metamorphosis o Ametabolous- insect experiences no metamorphosis  All insects go through a process of courtship called copulation  Most insects lay their eggs in a sheltered place, while few may hatch internally  In some butterfly and moth species, males wait outside the pupa and copulate with the female right after she emerges

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