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Entomology Exam 1


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Most insects are 1-5mm, so forces of ______ are almost equal to forces of gravity.
Insects' visual systems are secondary to their ________ systems.
Olfactory (pheromones, chemicals, signals, etc.)
Very few insects can hear. Most can detect _____ instead.
An ant (O. barbiger) in the _______ can survive hot temperatures up to 67 C (152 F).
Live in glaciers and will die of a heat stroke if you hold it in your hand:
In pools of Africa, can survive extreme changes:
The only environment insects have not invaded?
Open ocean (except for 1 or 2 exceptions such as sea skaters aka "Halobates")
6 reasons why insects are so successful?
1. Highly adaptable exoskeleton
2. Small size (most 1-10mm)
3. High birthrate and short generation time
4. Metamorphosis
5. Flight
6. Around the longest
How does its highly adaptable exoskeleton allow insect success?
It gives rise to sensory systems,
How does its small size allow insect success?
-Insects can get into niches that a large animal cannot.
-Allows great evolutionary diversity.
How does high birthrate and short generation time allow insect success?
-Enormous fecundity.
-Quick adaptation.
-Constantly scrambling genes and making new species.
How does metamorphosis allow insect success?
-All 4 MAJOR orders (Coleoptera, Lepidoptera, Diptera, Hymenoptera) have this
-Can occupy different habitats as a juvenile and adult
-Physically occupying different niches removes possibility of cannibalism (adults eating young)
How does flight allow insect success?
-essential for success and richness
How does being around the longest allow insect success?
-Timing: insects colonized terrestrial habitats before chordates
-novel resources and habitats
-early phytophagy (the eating of plants)
-coevolution with angiosperms (A plant whose ovules are enclosed in an ovary; a flowering plant.)
How old is the oldest known insect?
400 million years
Which groups are most closely related to insects?
crustaceans or myriopods
Which "apterygote" order (of 5) is least closely related to the higher insects?
Collembola (springtails) : more closely related to crustaceans.
All pterygota have wings. True or False?
False. Fleas have lost their wings.
Beetles, spiders, mites, and crayfish are all Arthropods. True or False?
At what body length does force of gravity become less powerful than adhesion forces?
1 mm
Grasshoppers are one of the 4 largest orders of insects. True or False?
False. They are the 6th largest order (Orthoptera).
-Elytra and other sclerotization will protect from predators and DESICCATION due to high surface to volume ratio
One of the biggest challenges of Coleoptera?
-mutualisms: with flowering plants (1. pollinators, 2. feeding)
-coevolved with plants- can tolerate compounds emitted from plants
-larval habitats
-sociality (less than 1/2 of all hymenoptera species are social)
5 major groups of Phylum Arthropoda
1. Trilobita (trilobites)
2. Chelicerata (spiders, mites, ticks, scorpions)
3. Crustacea (crabs, crayfish, lobsters, shrimp, isopod pill bugs)
4. Myriapoda (centipedes, millipedes)
5. Hexapoda (insects)
What are Apterygotes?
-wingless first "insects"
-Entognatha means 'mouthparts in a pouch' - they are non-insect hexapods.
Characteristics of apterygotes:
-no wings
-little/no metamorphosis
-abdomenal appendages anterior to genitals
-indirect fertilization
3 orders of Class Entognatha
1. collembola (have been moved out, closer to Crustacea)
2. protura
3. diplura
-used to be called insects
-300 million/acre
-2 body plans: shrimpy (elongate) and globular
-unique anatomical features: collophore, furca (spring), retinaculum (catch)
-probably closer to crustacea
-most abundant hexapodous group
-been around 3 to 4 million years
-occupy moist soil
-more obscure
-no antennae
-no eyes
-minute animals
-front legs look like antennae
-9-12 abdominal segments (anamorphosis)
Diplura (two, tail)
-well-developed abdominal cerci: 2 types- long filamentous or short pinchers
-predators and scavengers
-unique regeneration of broken body parts
-3-5mm in length
Class Insecta, Subclass Apterygota, Order Thysanura
-silverfish, firebrats(thysanura='fringe', 'tail')-
-elongate bodies > 10-15mm
-covered in scales
-long multi-segmented antennae
-3 tails: 2 long lateral cerci, and 1 long median caudal filament
-small compound eyes
-large leg coxae: fast runners (hard to catch)
-under bark, leaf litter, caves, ant nests, deserts, etc.
Class Insecta, Subclass Apterygota, Order Archaeognatha
-bristletails (archeognatha='ancient', 'jaws')
-elongate cylindrical humpbacked bodies, 10-12mm length
-3 "tails": 2 short lateral cerci, and 1 long median caudal filament
-large compound eyes, joined above head
-under bark, litter, etc.
Characteristics of Subclass Pterygota
1. wings or secondarily wingless
2. second and third thoracic segments are enlarged and specialized for flight
3. internal fertilization via copulation
4. hemi or holometabolous molting
5. abdominal segments lack styli (vestigial legs) present in Apterygotes.
80% of all insects are in just 4 easily recognizable orders: the 4 HOLOMETABOLOUS orders
Primitive or Advanced?
-long multisegmented antennae
-leathery forewing
-long antennae (and filiform)
-many-segmented cerci
-ocelli (photoreceptors)
Primitive or Advanced?
-short antennae
-wing venation reduced
Characteristics of Hemimetabolous development
1. functional wings and sexual maturation at the final molt
2. **Wings gradually develop externally. ('exopterygote')**
3. juveniles are called nymphs
4. they resemble adults and occupy the same environment and consume the same food as the adults (except aquatic Odonata, Plecoptera, and Ephemeroptera)
5. nymphs have functional legs, antennae, and compound eyes
Which order is this?
-aquatic grazers on algae
-lifespan 3-4 weeks
-winged "subimago"
-adult life very brief, a few hours
-no adult functional mouthparts or gut
-mass emergence
Order Ephemeroptera (mayflies)
What is the "subimago"?
stage of development in an insect in which the insect is winged and capable of flight but not yet sexually mature
Which order?
-predators as nymphs and adults
-adults relatively long-lived
-nymphs feed by hinged raptorial labium; grabs mosquito larvae, mayfly nymph, tadpole, etc.
-flying adults capture prey by holding legs in shape of a basket
Which order?
-jumping hindlegs
-leathery forewings
-large pronotum
-grasshoppers, katydids, crickets known for ability to jump and sing
-some voracious pests (locusts, certain katydids)
-cryptic coloration, mimicry of leaves
Which insect is one of the best examples of mimicry (blending in with environment in coloration and form)
Which order?
-parthenogenesis in some species
-males may be uncommon
-regenerate lost legs
Phasmatodea (walking sticks)
Which order?
-leathery forewings
-expanded pronotum, head concealed
-eggs contained in ootheca
-antennae are long and filiform
-cerci are many-segmented
Blattodea (roaches)
Which order?
-long-necked (elongate prothorax)
-raptorial forelegs
-forewings leathery
Mantodea (praying mantis, mantids)
Which order?
-forelegs are somewhat enlarged
-no wings
-last tarsal segment kept off substrate
-long antennae with terminal bend
Mantophasmatodea (gladiators, heelwalkers)
Which order?
-pale, soft-bodied
-fore and hindwings same size when present
-lack of eyes
Isoptera (termites)
Which order?
-elongate slender bodies
-forceps-like cerci
-shortened forewings
-filiform antennae (primitive feature)
-dorsoventrally compressed
Dermaptera (earwigs)
Which order?
-long filiform antennae
-cerci generally long
-wings folded flat over the back
-nymphs are aquatic with long cerci and never a 3rd central tail or median caudal filament
Plecoptera (stoneflies)
Which order?
-adapted for life in silk tunnels
-hind legs run rapidly in reverse
-caudal cerci used to navigate while running
-scavengers on dead plants and animals
-only insects to produce silk as adults: generated in glands in
Embioptera (webspinners) - "Embiidina"

very rare, may not be questioned on
Which order?
-many have basal half of the forewings thicker than distal half
-modified piercing and sucking mouthparts
-some suck plant juices, can be plant pests
-some are predators with painful bite
-have a beak (proboscis)
Hemiptera (true bugs) (order #5)
Which order?
-large head, bulbous postclypeus
-membranous wings held roof-like over abdomen
-wing venation reduced
-antennae long and slender
-about size of a pinhead, to a grain of rice, soft-bodied, light or dark in color
Psocoptera (booklice)
Which order?
-wingless ectoparasites (lost wings)
-3 nymphal instars
-mouthparts are mandibles for chewing lice, stylets for sucking lice
-dorsoventrally flattened head
-reduced compound eyes and no ocelli
Phthiraptera (head louse and hog louse)
Which order?
-minute, slender insects, often in flowers (dandelions)
-narrow wings fringed with long hairs, or wingless
-mouthparts for piercing/sucking; asymmetrical with lost mandible
-antennae short (advanced), close together
Thysanoptera (thrips) = "fringed", "wing"
Which order?
-minute insects, less than 3mm long
-gregarious under bark, in decaying wood, humus, sometimes near galleries of termites
-winged and wingless forms; winged
Zygoptera (angel insects)
Characteristics of ENDOPTERYGOTE development (as developing juveniles, wings are inside body, we cannot see them)
-resting stage between larval instars and adult
-4 largest orders included
-the ultimate innovation, why so successful?
-hypothesis: multiple niche exploitation (ex: MOSQUITOS)
-relative stage-specific selection
What are the 11 endopterygote orders?
1. Neuroptera
2. Megaloptera
3. Raphidioptera
4. Coleoptera
5. Diptera
6. Mecoptera
7. Strepsiptera
8. Siphonaptera
9. Lepidoptera
10. Trichoptera
11. Hymenoptera
Which order?
-membranous wings with network of veins; held roof-wise over body
-antennae generally long and threadlike (lacewings), and sometimes with terminal club (antlions)
-mouthparts for biting
-larvae carnivorous
Neuroptera (lacewings, antlions)
Which order?
-aquatic larvae, elongate, flattened, general predators
-winged adults non-feeding
-enlarged fan-folded anal area of wing
-elongate male mandibles
Megaloptera (dobsonflies)
Which order?
-long thorax, raises head like snake about to strike
-female has long, tail-like ovipositor
-larva with a slender, elongate body, narrow thorax and short, strong, biting jaws
Raphidioptera (snakeflies)
Which order?
-protection with elytra and sclerotization
-desiccation resistance (spiracles shielded)
-hardening of forewings into elytra
-hindwings with reduced venation
-hind 2 thoracic segments broadly connected with abdomen
Coleoptera (beetles) (biggest order)
Which order?
-success= mouthparts
-hindwings reduced to club-shaped balancing organs called halteres
-one pair of wings
-mouthparts- a proboscis= sucking liquid food, sometimes adapted for piercing
-larvae legless maggots, head r
Diptera (true flies)
Which order?
-head elongate, beak with mandibulate biting mouthparts at lower end
-wings narrow, elongate, similar in size; crossveins numerous
-males may have enlarged external genitalia recurved over abdomen like scorpion's tail (bluff)<
Which order?
-closest to Diptera
-internal parasites of bees, wasps, grasshoppers, leafhoppers
-hypermetamorphosis- unusual holometabolous development where larvae change body form as they mature
-winged males emerge and search for ma
Which order?
-laterally flattened body
-strong hindlegs adapted for jumping
-mouthparts for piercing skin and blood-sucking
-adults blood-sucking external parasites
-larvae are wormlike
Siphonaptera (fleas)
Which order?
-coiled proboscis
-plant-insect mutualisms
-large wings relative to body size
-covered with scales
-mouthparts tubular proboscis coiled beneath head
-caterpillars have 3 pairs of thoracic (true) legs and several
Lepidoptera (2nd largest group)
Which order?
-wings covered, long hairs
-long filiform antennae
-mouthparts reduced
-wings held tent-like over abdomen
-aquatic larvae form cases (used for jewelry)
Trichoptera (caddisflies) = ("hair", "wings")
Which order?
-ovipositor for drilling into plant or animal tissues or modified as sting
-wings coupled by row of hooks on front edge of hindwing
-biting mouthparts and powerful jaws, sometimes a tongue-like
Hymenoptera (bees, wasps, ants) = ("marrying together of front and hind wing")
What are the functions of the integument?
1. skeletal (body form, muscle attachment, organ support)
2. armor
3. water conservation
4. sensory
5. locomotion
6. respiration- lining of tracheal system with millions of the ultimate subdivisions reaching every cell in the body
7. digestion- lining fore and hindgut and glands producing digestive enzymes, including salivary glands
8. exocrine glands: material for shelter and support (e.g. silk), chemical communication, attraction of sexes, offense and defense
Ancestor= annelid or nematode?
tagmatization, 3 tagmata
What are the characteristics of the exoskeleton?
Skeletal plates:
-sutures define skeletal plates called SCLERITES
-dorsal surface: TERGUM (on thorax = NOTUM) and sclerites = TERGITES (if on abdomen)
-ventral surface: STERNUM and sclerites = STERNITES
-prothorax, mesothorax, metathorax**
-sides of thorax sclerites = PLEURITES
-remember, tergum is the thorax AND the abdomen
Head bears:
-compound eyes
-1 pair of antennae
-mouthparts specialized for sensory detection and eating
Thorax bears:
-2 pairs of wings, 3 pairs of legs specialized for locomotion
-3 segments: prothorax, mesothorax, and metathorax
-Notum- back
-Pronotum- 1st thoracic segment, and covers back
Abdomen contains:
-reproductive organs, hindgut
-specialized for digestion, reproduction and ventilation
-Features: respiratory spiracles (first 8 segments), genitals (female: ovipositor segment 8 and 9; male: aedeagus segment 9), post-genital appendages (cerci, caudal filament, epiproct, paraproct, tracheal gill:damselflies), (larval prolegs:Lepidoptera)
What is ecdysis?
-shedding makes insect very vulnerable
Why molt?
1. got to grow
2. wound healing, regeneration of lost body parts (walking sticks and diplura)
3. renewing physiological properties of integument
4. changes in body structures at metamorphosis
Why do we care about molting?
1. It is an amazing process where the insect must: detach all muscles from their supports, detach all sensory nerves from their cuticle endpoints, evert a network of respiratory tracheoles that branch and reach throughout the body
2. integument is a KEY feature of insect success and if regular molting can be disrupted, pest insects can be managed through a vital vulnerability.
Holometabolous order of development
Hemimetabolous order of development
Why is holometabolous development so successful?
Because it gave them 2 different sets of resources. The adults are not competing with the young. Removes cannibalism. Different selective forces act on different stages.
Know 3 basic parts of the integument
basal membrane
(all parts)
Wheel formation of Odonates?
Attached to the male by her head and/or the front segment of her thorax, the female curls her abdomen under her, reaching forward with the tip of her abdomen in order to pick up the sperm from the male's second abdominal segment.
Which order has long strong cerci that it uses to capture prey?

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