Chapter 2 Section 3 - Insects

Section 3: Insects  Largest group of animals on Earth  Live everywhere but the ocean  Harmful: termites, weevils, mosquitoes  Good: bees, butterflies, preying mantis  Insects have 3 body sections, 6 legs, 1 pair of antennae, and usually 1 or 2 pairs of wings.

Insects  Have three body parts: head, an abdomen, and a thorax (middle section)  Anatomy of a grasshopper page 56

Growth and Development  Insects also shed their exoskeletons.  An insect goes through stages during its development. The series of changes an insect undergoes as it develops into an adult is called metamorphosis.

Gradual Metamorphosis  Has no distinct larval stage  An egg hatches into a stage called a nymph, which usually looks like the adult insect without wings.  The nymph may molt several times before becoming an adult.

Complete Metamorphosis  Insects that completely change in body form in each stage of development.  There are four stages: egg – larva – pupa – adult  Example: butterfly

Insect Behavior – Social Insects  Behavioral adaptations help insects survive.  These behaviors include: formation of societies and mating rituals.  Many insects also have mechanisms for defense.  Social Insects: Ants and Honeybees live in colonies (work together)

Communication  Insects communicate by using chemicals, sound, and visual displays.  Examples: Buzzing, scents to attract mates, chirping sounds by rubbing one wing against another, dancing, fireflies using light  The chemicals given off by insects are called pheromones.

Defense  Mimicry, camouflage, attacking predators, spraying, smelling bad, having a stinger

Obtaining Food  Rule is: If it is living, or if it once was living, some kind of insect will eat it.  Some feed on animals, paper, plants, decaying bodies  An insect’s mouthparts are adapted for a highly specific way of getting food – see page 57

Chapter 2 Section 4 – Insect Ecology

Section 4: Insects and the Food Chain  Food chain starts with a producer.  Producers feed consumers.  Decomposers- break down the wastes and dead bodies of other organisms.

Insects as Consumers of Plants  Insects are key players in the food chain because of the many different ways they obtain food and become food for other animals.  Many eat plants (leaves, sap, bark, roots)

Insects as Prey  Trout and bass (fish) eat insects.  Chicks eat only insects (200,000 before it leaves the nest)

Insects as Decomposers  Insects break down the wastes and bodies of dead organisms – this enriches the soil.

Insects as Food for Humans  Page 64 and 65  In Mexico – they use dried grasshoppers in tortillas

Pollen Carriers  Pollen contains cells that become sperm cells, allowing plants to reproduce  Pollinators – carry pollen ex. bee

Disease Carriers  Some insects spread diseases to both plants and animals, including humans  Examples: mosquitoes, fleas  These insects often have sucking mouthparts that pierce the skin of their prey, providing an opening for the disease-causing organisms to enter.

Controlling Pests  To try and control pests, people use chemicals, traps, and living things, including other insects.  Pesticides – kill pests  Biological control – natural predator or disease released into an area to fight a harmful insect.