Chapter 2 Section 3

Insect Body 3 body sections 6 legs 1 pair of antennae Head, thorax, and abdomen 6 legs Attached to the thorax 1 pair of antennae Usually 1 or 2 pairs of wings

Insect Body Sense organs are located on the head Eyes and antennae Abdomen contains the internal organs 2 large compound eyes which contain lenses Good for seeing movement Have simple eyes too Distinguish between light and dark

Insect Body Obtain oxygen through a system of tubes Tubes lead to openings in the insect’s exoskeleton Air enters the body through the tubes and travels to the cells

Egg to Adult Tiny, hard-shelled, fertilized eggs Go through metamorphosis to become an adult 2 different types of metamorphosis

Metamorphosis 2 types of metamorphosis Complete metamorphosis Gradual metamorphosis

Metamorphosis Complete metamorphosis 4 dramatically different stages Egg Larva Pupa Adult

Metamorphosis Complete Metamorphosis Larva – immature form of an animal that looks different than the adult Specialized for eating and growing Pupa Insect is enclosed in a protective covering and gradually changes from a larva to an adult After it has completed its development an adult emerges

Complete metamorphosis

Metamorphosis Gradual metamorphosis Has no distinctly different larval stage Egg hatches into a stage called a nymph Nymph – often resembles the adult insect A nymph may molt several times before becoming an adult

Gradual Metamorphosis

Feeding Eat plants and parts of plants (leaves and nectar) Eat products made from plants such as paper Feed on animals too Fleas and mosquitoes feed on blood of living animals Dung beetles feed on animal droppings

Feeding Burying beetles feed on decaying bodies of dead animals Mouthparts are adapted for a specific way of getting food

Defense Hard exoskeleton Run or fly away Smell or taste bad Painful stings

Defense Most common defense is camouflage Resemble other animals Blend in to their environment Resemble other animals Example the spots on wings of some moths resemble large eyes When predators see these eyes they avoid them

Insects and Humans For every person alive scientists estimate that there are at least 200 million living insects Insects impact our lives Damage crops Carry microorganisms that cause diseases The vast majority are harmless or beneficial to humans

Insects and Humans Insects are harmless or beneficial Bees make honey Silkworm larvae spin the fibers to make silk Some insects prey on harmful insects Some enable food crops We need insects to have food to eat

Controlling Pests We try to get rid of harmful pests using pesticides This can also kill harmless / helpful pests Overtime insect populations become resistant to pesticides

Controlling Pests A search for another way to deal with harmful insects Biological controls Introduce natural predators or diseases Ex: Ladybugs added to fields to kill aphids Soil can be treated with bacteria that are harmless to humans but cause diseases in the larvae of pest insects like the Japanese beetle Biological controls only kill specific pests and are therefore less damaging to the environment