Entomology: March 27, 2000



Entomology: April 10, 2006

I. Neopterous exopterygotes (cont.)

A. Order Phasmida (“phasma”=apparition): walking sticks, stick and leaf insects

1. Adult characteristics

**The most striking characteristic of this Order is the ability to camouflage

a) Head (note eyes, ocelli-if present, mouthparts, other structures of note)

b) Thorax

← Short prothorax, elongate meso- and metathorax

• dorso-ventrally flattened in leaf insects

← Legs: walking sticks vs. leaf insects

← Wings

• Compare walking sticks and leaf insects

c) Abdomen

← Long and slender in leaf insects

← Short cerci

2. Distinctive larval features

a) Nymphs resemble miniature adults

3. Habitat

a) Primarily tropical, with the most species in tropical regions of Asia

4. Food/Feeding behavior

a) Entirely herbivorous; use mandibles to chew food

← Effects on plant populations?

5. Locomotion/flight

a) Slow-moving, poor fliers.

6. Selected aspects of reproduction

a) Males generally smaller than females

b) Many parthenogenic species (know what this means)

7. Other

a) Protective mechanisms

← Know several.

← What is autoamputation?

B. Order Orthoptera (“orthos” = straight): grasshoppers, katydids, crickets, locusts

1. Adult characteristics

a) Head (note eyes, ocelli-if present, mouthparts, other structures of note)

b) Thorax

← Pronotum is enlarged

← Femurs of hindlegs are greatly enlarged and associated muscles are also enlarged as adaptations for jumping.

• Proportionally equivalent to us being able to clear 300 feet in high jump, 500 feet in broad jump

• Adaptive value?

← Wings

• Forewings (“tegmen”) are toughened (“parchmentlike”) and relatively narrow

• Hindwings are membranous, fan-shaped

• Some species have reduced wings

c) Abdomen

← Relatively robust, approximately the same width as the thorax

← Cerci variable (some species with long cerci)

← Prominent ovipositor in females

2. Distinctive larval features

a) Nymphs are similar to adults; wings progressively larger with each molt.

3. Groups

a) Suborder Caelifera: short-horned grasshoppers and locusts (you are sketching a short-horned grasshopper)

b) Suborder Ensifera: long-horned grasshoppers, crickets and katydids

c) Key differences between the suborders

← Antennae (know differences)

← Ovipositors (know differences)

← Tympanic organs (where found in members of each suborder

← See also differences in sound production (below)

4. Habitat

a) Terrestrial and usually found associated with vegetation; some burrowers. Some associated with water.

5. Food/Feeding behavior

a) Primarily herbivorous, but some species are omnivores or carnivores

b) Chew with mandibles.

6. Locomotion/flight

a) Known for their ability to jump long distances

b) More often gliders than flyers.

7. Selected aspects of reproduction

a) Stridulation (usually by males)

← Suborder Caelifera: Specialized pegs on inside of hind femora rubs against a thickened vein of forewing

← Suborder Ensifera: Two specialized veins of the forewings rub together

b) In some species, females are also capable of stridulation.

c) Mole crickets: special mechanisms of amplification.

d) Some groups do not produce sound.

8. Other

a) Swarms of Orthoptera (of both Suborders) can be extremely destructive

C. Order Dermaptera (“derma” = skin): Earwigs!

1. Adult characteristics

a) Head (note eyes, ocelli-if present, mouthparts, other structures of note)

b) Thorax

← Legs: nothing noteworthy

← Wings

• Toughened, leathery and veinless forewings

• Fan-shaped membranous hindwings; do not cover the abdomen

c) Abdomen

← Visible (not covered by wings)

← Cerci usually without segments and look like forceps

• generally straight in males, curved in females

2. Distinctive larval features

a) Resemble adults (except for the usual wing development)

3. Habitat

a) Often found in and around leaf litter, beneath bark or rock, in crevices, within compost heaps, etc… Also in flowers

← Tend to cluster within these habitats

4. Food/Feeding behavior

a) Omnivores/scavengers

← The European earwig, common here, feeds on flowers

b) Some species are ectoparasites of rodents (Africa) and bats (Asia)

5. Locomotion/flight

a) Flight is weak or non-existent

6. Selected aspects of reproduction

a) The females provide some parental care after birth.

b) One group gives birth to live young

7. Other

a) Why called “earwigs”?

b) The forceps-like cerci are used for…?

c) Some species shoot noxious substances from abdominal glands.

Study questions

1. See previous study guide for hints about how to study the Orders. Don’t forget to answer the questions posed in the outline itself.

2. What features of Order Phasmida members make them effective at camouflage (besides the fact that their overall body structures are shaped like sticks or leaves)?

3. Besides camouflage, what other defensive adaptations do phasmids possess? Why do phasmids have so many protective mechanisms compared to, say, members of Order Odonata?

4. Name the two Suborders of Order Orthoptera, and describe four key physical differences between members of the two suborders.

5. What is stridulation? What is its major role in the life-history of the Orthoptera? Which gender tends to stridulate? How is stridulation accomplished in the two different suborders of the Orthoptera? (NOTE: You should’ve included this in your answer to the previous question.)

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