4/8/17 1 University of Wisconsin – Madison Insect Diagnostic Lab Introduction to Insects PJ Liesch UW-Madison Dept. Entomology [email protected]University of Wisconsin – Madison Insect Diagnostic Lab Which ones are insects? University of Wisconsin – Madison Insect Diagnostic Lab § Do not have a backbone (invertebrates) § Have Exoskeleton § Jointed legs § Types of Arthropods: § Insects (beetles, flies, moths, etc.) § Arachnids (spiders, ticks, mites, scorpions) § Myriapods (centipedes and millipedes) § Other groups (lobsters, crabs, shrimp, isopods, etc.) § Non-arthropod plant pest: § Slugs (mollusks) Arthropods (Insects and their relatives) University of Wisconsin – Madison Insect Diagnostic Lab § Arthropod § Exactly 3 body regions § Head, thorax, abdomen § 6 legs § Up to 2 pairs of wings § ONLY in adults § Compound eyes (many lenses) § Few simple eyes may be present § 1 Pair antennae What is an Insect? University of Wisconsin – Madison Insect Diagnostic Lab § (Non-insect) arthropods § 2 Body regions § 8 legs § No wings § 0 - 8 simple eyes § No antennae § “Good guys” What ' s a spider? http://www.mnh.si.edu/highlight/sem/spiders.html University of Wisconsin – Madison Insect Diagnostic Lab § Myriapods: Non-insect arthropods § Long, rounded bodies § Many body segments § 1 pair antennae § Many legs § Centipedes = 1 pairs/segment § Millipedes = 2 pair/segment § Centipedes : predators § Millipedes: “recyclers” C entipedes and M illipedes
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University of Wisconsin–MadisonInsect Diagnostic Lab
University of Wisconsin–MadisonInsect Diagnostic Lab
§ Mollusks (NOT arthropods)§ Related to snails, clams, squid
§ No legs§ Soft bodies
§ Coated in mucus-like “slime”§ Antenna-like sensory tentacles§ Very sensitive to sunlight and drying out
What are slugs?
University of Wisconsin–MadisonInsect Diagnostic Lab
Exoskeleton
� Insects covered with hard outer shell� Difficult to sense environment
� Have sensory hairs (like cat whiskers)� Must molt as they grow
University of Wisconsin–MadisonInsect Diagnostic Lab
Molting� Process of shedding “old” covering� Molting regulated by hormones
� Some insecticides can mimic insect hormones
University of Wisconsin–MadisonInsect Diagnostic Lab
How do Insects Breathe?� Insects don’t have lungs!� Openings in exoskeleton called spiracles� Spiracles lead to “air ducts” called tracheae� Some insecticides (soaps, oils) interfere with air exchange
University of Wisconsin–MadisonInsect Diagnostic Lab
Insect Mouthparts
University of Wisconsin–MadisonInsect Diagnostic Lab
Chewing Mouthparts
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University of Wisconsin–MadisonInsect Diagnostic Lab
Chewing Insect Damage
University of Wisconsin–MadisonInsect Diagnostic Lab
University of Wisconsin–MadisonInsect Diagnostic Lab
University of Wisconsin–MadisonInsect Diagnostic Lab
University of Wisconsin–MadisonInsect Diagnostic Lab
Sucking Mouthparts
• Work like a soda straw or a hypodermic needle
• Used to “drink” liquid diet
• Used by both herbivores and predators
University of Wisconsin–MadisonInsect Diagnostic Lab
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University of Wisconsin–MadisonInsect Diagnostic Lab
University of Wisconsin–MadisonInsect Diagnostic Lab
University of Wisconsin–MadisonInsect Diagnostic Lab
University of Wisconsin–MadisonInsect Diagnostic Lab
Two forms of development (change):
1. Simple / incomplete / gradual
2. Complete / advanced
Insect Development (Metamorphosis)
University of Wisconsin–MadisonInsect Diagnostic Lab
Egg – Nymph – Adult
§ All life stages look and behave similarly§ Whole family can live and feed together
Simple (incomplete) metamorphosis
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University of Wisconsin–MadisonInsect Diagnostic Lab
Simple (incomplete) Metamorphosis S
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University of Wisconsin–MadisonInsect Diagnostic Lab
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University of Wisconsin–MadisonInsect Diagnostic Lab
Egg – Larvae – Pupae – Adult
§ Larvae do not look like adults§ Often wormlike§ Ex. caterpillars, white grubs, maggots, etc.
§ Can live in different environment§ Larvae and adults tend to eat different foods§ Larvae usually the main pest
Complete Metamorphosis
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University of Wisconsin–MadisonInsect Diagnostic Lab
Complete MetamorphosisC
University of Wisconsin–MadisonInsect Diagnostic Lab
Insect LarvaeC
University of Wisconsin–MadisonInsect Diagnostic Lab
Insects85%
Other Arthropods7%
Other Animals8%
Animal Diversity
Number of known animal
species: ~1,250,000
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University of Wisconsin–MadisonInsect Diagnostic Lab
Beetles38%
Moths and Butterflies
16%
True Flies12%
Bees and Wasps13%
True Bugs (Sucking Insects)
11%
Other Insects
10%
Insect Diversity
1 out of every 4 animals on the
planet is a beetle!
Number of known insect species:
~ 1,000,000
University of Wisconsin–MadisonInsect Diagnostic Lab
§ Thysanoptera: (Thrips) some pests§ Orthoptera: (Grasshoppers) can be pests§ Hemiptera: (True Bugs) many pests, some beneficials
§ Neuroptera: (Lacewings) beneficials§ Lepidoptera: (Butterflies, Moths) many pests§ Coleoptera: (Beetles) many pests and beneficials§ Diptera: (Flies) some pests, some beneficials§ Hymenoptera: (Bees, Wasps) many beneficials
Farm Insects: Most Important Orders
S
C
University of Wisconsin–MadisonInsect Diagnostic Lab
§ “Thrips”§ Very small (few mm long)§ Have fringed wings§ Scraping mouthparts
§ Some species are pests:§ Occasionally on corn§ Can be very problematic
in greenhouses
Order ThysanopteraS
University of Wisconsin–MadisonInsect Diagnostic Lab
§ Grasshoppers, crickets, katydids§ Can be quite large (> 1” long)§ 2 pairs wings (1st pair leathery) § Strong back legs§ Chewing mouthparts§ Generalist feeders
(will eat just about anything!)
Order OrthopteraS
University of Wisconsin–MadisonInsect Diagnostic Lab
Orthoptera wings1st pair: leathery, thickened
2nd pair:thin flying wing
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University of Wisconsin–MadisonInsect Diagnostic Lab
§ Can occur in large numbers (swarms)§ Most problematic in dry years§ Can become heavily infested with
nematodes (roundworms)§ Eggs eaten by blister beetle larvae
Orthoptera (continued)S
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University of Wisconsin–MadisonInsect Diagnostic Lab
§ Aphids, Plant Bugs, Stink Bugs, Cicadas, Spittlebugs§ Large, diverse group (1,000’s of species)§ Can be small (aphids) to large (cicadas)§ 2 pairs wings (1st pair often partly leathery)
§ Wings sometimes absent (ex. aphids) § Some species can transmit plant diseases§ Sucking mouthparts
Order HemipteraS
University of Wisconsin–MadisonInsect Diagnostic Lab
Two sets of wings: • 1st pair: (= Hemilytra) leathery upper, thin lower parts
• 2nd pair: thin and membranous
S
University of Wisconsin–MadisonInsect Diagnostic Lab
§ Many are plant feeders (can be pests)§ ex. Potato leafhopper, cicadas, aphids, spittlebugs
§ Some are predators (beneficials)§ ex. Soldier bugs, Assassin bugs
§ Some pests are specialists§ ex. Soybean aphid (alternates between soybeans & buckthorn)
§ Others are generalists§ ex. Brown Marmorated stink bug (feed on many plant species)
Hemiptera (continued)S
University of Wisconsin–MadisonInsect Diagnostic Lab
Hemiptera (continued)
Predators
Pests
S
University of Wisconsin–MadisonInsect Diagnostic Lab
S
University of Wisconsin–MadisonInsect Diagnostic Lab
S
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University of Wisconsin–MadisonInsect Diagnostic Lab
§ Green and Brown Lacewings, others§ Small group (~6,000 species)§ Typically small sized (~1/2 inch long)§ 2 pairs wings
§ Larvae can be pests§ ex. Corn Earworm, Cutworms, Armyworms, etc.
Order LepidopteraC
University of Wisconsin–MadisonInsect Diagnostic Lab
Lepidoptera: Scaled wingsC
University of Wisconsin–MadisonInsect Diagnostic Lab
(Correctly) Identifying Caterpillars• 3 pairs of true legs• 4-5 pairs of prolegs often
present, have hooks called crochets
Sawflies: • Not Lepidoptera!• 7 pairs of prolegs• No crochets
C
University of Wisconsin–MadisonInsect Diagnostic Lab
C
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University of Wisconsin–MadisonInsect Diagnostic Lab
§ Beetles (Larvae often called “grubs”)§ Largest group of insects (350,000+ species)§ Greatly vary in size§ Often have very hard body § 1 pairs wings (adults)
§ Wings covered by hard protective “shell” (elytra)§ Chewing mouthparts (adults & larvae)§ Many pests, some beneficials
Order ColeopteraC
University of Wisconsin–MadisonInsect Diagnostic Lab
Coleoptera (Continued)
Wing covers (elytra)
True wings hidden at rest
C
University of Wisconsin–MadisonInsect Diagnostic Lab
BeetlesC
University of Wisconsin–MadisonInsect Diagnostic Lab
Corn RootwormAsian Lady BeetleC
University of Wisconsin–MadisonInsect Diagnostic Lab
White Grub (Scarab Larva)
Alfalfa WeevilLarvae
C
University of Wisconsin–MadisonInsect Diagnostic Lab
§ True Flies (Larvae often called “maggots”)§ Includes: mosquitoes, house flies, deer flies, horse flies, etc
§ Large, diverse group (~ 100,000 species)§ Greatly vary in size§ 1 pairs wings (adults)
§ Hind wings have been greatly reduced to small clubs
§ Chewing or slicing mouthparts (larvae)§ Variable mouthparts (adults)§ Some can be pests, others beneficials
Order DipteraC
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University of Wisconsin–MadisonInsect Diagnostic Lab
Diptera (Continued)C
University of Wisconsin–MadisonInsect Diagnostic Lab
Halteres
C
University of Wisconsin–MadisonInsect Diagnostic Lab
C
University of Wisconsin–MadisonInsect Diagnostic Lab
Fly larvae (maggots)C
University of Wisconsin–MadisonInsect Diagnostic Lab
§ Sawflies, Ants, Bees, Wasps § Large, diverse group (~ 100,000+ species)§ Greatly vary in size (some wasps are tiny!)§ 2 pairs of membranous wings (adults)