Plant Pest Beneficial and Harmful Insects
Objectives • Compare and Contrast complete and incomplete metamorphosis. • Identify and describe beneficial insects. • Identify and describe harmful insects. **For this lesson you will need to take notes on the different insects mentioned**
Introduction • Plants naturally have inherited problems • These plants rarely can be cured. • The best way to avoid this is to choose plants best adapted for the region. • Florida has more different kinds of insects that any other state.
Introduction (continued) • Most insects are NOT harmful to our plants. • Harmful insects are harmful due to: • Feeding Habits • Breeding • Shelter Habits
Insect Lifecycles • Metamorphosis: when insects pass through several stages during development. • Complete Metamorphosis • 4 stages: Egg, Larva, Pupa, Adult • Examples: • Butterflies • Mealworms • Ladybugs
Incomplete Metamorphosis • 3 Stages: • Egg • Nymph • Adult • Examples: • Stinkbugs • Earwigs • Grasshopper • Cockroaches
Beneficial Insects • Less than one half of one percent are actually pests. • Many beneficial insects feed on insects that are pests. • Example: Spiders, Assassin Bugs, Praying Mantids, Lacewings, Parasitic Wasps
Ladybeetles • Florida’s most beneficial insect!! • Both adults and larva prey on Aphids • Adults: oval, red and black, or black/yellow Adult eating Aphid Full Grown Larva Ladybeetle Eggs
Praying Mantids • Very large insects (up to 2” in length) • Can be either green or brown • Front legs modified for grasping prey • Feed on flies, honeybees, crickets & moths Adult Praying Mantis Egg case (ootheca) and Larva
Assassin Bugs • Generally black or brown (can be bright) • Found on foliage where they attack prey • Caterpillars are their favorite lunch!! • Typically ambush their prey.
Lacewings • Commonly found on grasses, row crops, shrubs and trees. • Feed on Aphids which nicknames them “Aphidlion” • Green with copper eyes
Parasitic Wasps • Extremely important insects!! • Very small (1/8”) and go unnoticed • They lay eggs on the body of a host insect • Immature stage consumes the host • Prey on: • Scales, Whitefiles, Aphids, Leafminers and caterpillars
Rarely Bite Humans! Spider Predaceous, feed on a wide variety of insects Paralyze their prey with a venom bite Most use webs but most beneficial spiders do not spin webs. Examples: Wolf, Jumping and Crab
Insects as Pests (Harmful) • Pests of plants are typically divided into groups according to the way they damage plants • Most insects damage plants with their mouthparts. • Piercing-Sucking Mouthparts • Chewing Mouthparts (Foliage Feeding Insects)
Piercing Sucking Mouthparts • Tube like mouthpart which inserts into a food source • Plant, other insect, humans etc. • Cause damage to plants: • Stunting • Yellowing • Often are not affected by exterior pesticides as they feed on the interior of leaves
Chewing Mouthparts • Feed on leaves, flowers and also attack the roots of plants. • Mouthparts move side to side similar to scissors. • Examples include: • Caterpillar • Beetle • Grasshopper • Katydids
Scales (p.s.) • Most serious pests on many ornamental plants. • Many species of soft and hard scales in Florida. • Cause yellow spots to appear on the top sides of leaves • Secrete a waxy covering over their bodies when mature making them hard to control.
Mealybugs (p.s.) • Pests to foliage plants, annuals and perennials. • Excrete honeydew which serves as medium for fungus. • Soft bodied Scale • Common on: • Azalea • Coleus • Croton • Cactus
Aphids (p.s) • Pear shaped • Will infest any plant • Cause damage by sucking out plant juices • Transmit viral diseases • Mostly female and reproduce without mating • Each produce 50 – 100 daughters which reproduce in 8 days!!
Whiteflies • Common on ornamental plants • Resemble moths • Plants become pale or spotted • Can transmit viruses • Deposit eggs on underside of leaves • Eaten by Lady Beetles and lace wings
Lacebugs (p.s.) • Brown with clear wings. • Damage on top side of leaf as white specks • Shiny black spots of excrement on underside of leaves • Cause damage to: • Azalea • Hawthorns
Thrips (p.s) • Very small and slender • Remove plant juices • Life cycle takes 2-4 weeks • Foliage feeders • Infested plants have stippled appearance and small brown specks.
Caterpillars (ch) • Immature stage of moths/butterflies • Vary in color and hair stinging rose • Devour foliage leaves holes and irregular areas or can strip leaves completely
Grasshopper and Katydid (ch) • Consume large quantities of foliage on ornamentals • Adults lay eggs clumped together in pods (in soil) • 1 complete life cycle per year • Feeding habits vary greatly
Beetles (ch) • Hard shelled insect • Chew off parts of the foliage or flowers of many plants. • Mostly active at night. • Larvae feed on the roots or bore through stems and branches.
Plant Insect Awareness Project: Most people are unaware of the harms and benefits of the many insects that reside in Florida. You are to create a Public Awareness Poster and insect model for your specific insect. This is a two part project: Part 1: Create a poster displaying facts about either your Beneficial or Harmful insect Part 2: Create a model of the insect using a variety of materials.
Plant Insect Awareness Project Things to include on your poster: Life cycle of insect Description of insect Harms or Benefits Where found (plants) Things to include for your insect model: Needs to be actual model of insect!! Including proper mouthparts, legs, body segments, eyes, etc. You may use a variety of materials (clay, foam, putty, food, straws etc. ) Points for the project are as follows: -Pest Awareness Poster: 25 points -Pest Model: 15 points Total Points: 40 points
List of possible insects: Harmful: -Scales -Mealybugs -Aphids -Whiteflies -Lacebugs -Thrips -Caterpillars -Grasshoppers -Katydids -Beetles Beneficial: -Ladybeetles -Praying Mantids -Assassin Bugs -Lacewings -Parasitic Wasps -Spiders