Final Aquatic Entomology

1. Cuticle

The insect exoskeleton provides protection, support, water balance, and muscle attachment.

Epicuticle

• Thin outer waxy layer

• Waterproof

• Prevents desiccation

• Protects against chemicals and pathogens

Advantage

• Important in temporary ponds and semiaquatic habitats where drying is common.

• Helps adults survive terrestrial life.

Examples

• Aquatic beetles (Coleoptera)

• Water striders (Hemiptera: Gerridae)

Exocuticle

• Hardened (sclerotized)

• Provides strength and protection

Advantage

• Protects predators and supports movement in fast currents.

Examples

• Elmidae (riffle beetles)

• Heptageniidae (flatheaded mayflies)

Endocuticle

• Thick, flexible layer

• Allows movement

Advantage

• Useful for burrowing and swimming.

Examples

• Ephemeridae (burrowing mayflies)

• Dytiscidae (predaceous diving beetles)

2. Mouthparts

Labrum

Upper lip

Adaptation

• Helps hold food

Examples

• Predators use it to secure prey.

Mandibles

Jaw-like structures

Adaptation

• Crushing

• Cutting

• Predation

Examples

• Perlidae stoneflies (predators)

• Dytiscidae beetles (predators)

Maxillae

Manipulate food

Adaptation

• Sorting particles

• Holding prey

Examples

• Collector-gatherers

• Shredders

Labium

Lower lip

Adaptation

• Modified for feeding

Examples

• Dragonfly nymphs possess extendable labium for capturing prey.

Hypopharynx

Tongue-like structure

Adaptation

• Moves food

• Mixes saliva

Examples

• Most aquatic insects

3. Pneustic Respiration

Uses atmospheric oxygen.

Fixed Air Source

Adaptation

• Siphon remains connected to atmosphere.

Examples

• Nepidae (water scorpions)

• Mosquito larvae (Culicidae)

Advantage

• Useful in stagnant, oxygen-poor water.

Air Bubble

Adaptation

• Carries air underwater.

Examples

• Dytiscidae

• Hydrophilidae

Advantage

• Allows extended dives.

Plastron

Adaptation

• Permanent air layer trapped by hairs.

Examples

• Elmidae

• Dryopidae

Advantage

• Excellent in fast-flowing streams.

4. Apneustic Respiration

No atmospheric connection.

Cutaneous Respiration

Adaptation

• Oxygen diffuses through body wall.

Examples

• Small Chironomidae larvae

Advantage

• Effective in cool, oxygen-rich streams.

Gill Respiration

Adaptation

• Increased surface area

Examples

• Mayflies

• Stoneflies

• Damselflies

Advantage

• Efficient oxygen extraction.

5. Voltinism

Multivoltine

Several generations per year

Advantage

• Rapid population growth

Examples

• Mosquitoes

• Chironomids

Univoltine

One generation per year

Advantage

• Synchronizes with seasonal resources

Examples

• Many mayflies

• Stoneflies

Semivoltine

More than one year per generation

Advantage

• Common in cold streams

Examples

• Large stoneflies

• Dobsonflies

6. Life Stage Development

Ametabolous

Egg → Juvenile → Adult

Advantage

• Simple development

Aquatic examples

Rare among aquatic insects.

Hemimetabolous

Egg → Nymph → Adult

Examples

• Mayflies

• Stoneflies

• Dragonflies

• True bugs

Advantage

• Nymphs occupy aquatic habitat continuously.

Holometabolous

Egg → Larva → Pupa → Adult

Examples

• Beetles

• Flies

• Caddisflies

Advantage

• Larvae and adults exploit different resources.

7. Diapause

Dormant period.

Advantages

• Survive drought

• Survive winter

• Avoid unfavorable conditions

Examples

• Mosquito eggs

• Caddisflies

• Stoneflies

8. Synchronous vs Asynchronous Emergence

Synchronous

Many individuals emerge together.

Advantage

• Predator swamping

• Easier mating

Examples

• Mayflies

Asynchronous

Emergence spread over time.

Advantage

• Stable populations

Examples

• Chironomids

9. Development Speed

Fast Seasonal

Temporary waters

Examples

• Mosquitoes

• Some mayflies

Slow Seasonal

Long-lived larvae

Examples

• Stoneflies

• Dobsonflies

Non-seasonal

Continuous development

Examples

• Tropical species

• Chironomids

10. Functional Feeding Groups

Shredders

Consume leaves

Examples:

• Pteronarcyidae

• Limnephilidae

Collector-Gatherers

Collect deposited particles

Examples:

• Chironomidae

• Caenidae

Collector-Filterers

Filter suspended particles

Examples:

• Hydropsychidae

• Simuliidae

• Isonychiidae

Scrapers/Grazers

Eat algae

Examples:

• Heptageniidae

• Elmidae

• Psephenidae

Predators

Capture animals

Examples:

• Odonata

• Dytiscidae

• Perlidae

11. Functional Habits

Clingers

Adapted to current.

Examples:

• Heptageniidae

• Glossosomatidae

Sprawlers

Live on soft sediment.

Examples:

• Ephemeridae

Burrowers

Dig into substrate.

Examples:

• Ephemeridae

Swimmers

Move through water column.

Examples:

• Baetidae

• Dytiscidae

Skaters

Surface dwellers.

Examples:

• Gerridae

• Veliidae

12. Morphology

Flattened

Reduces drag.

Examples:

• Heptageniidae

• Psephenidae

Streamlined

Efficient swimming.

Examples:

• Dytiscidae

• Dragonflies

Small

Uses interstitial habitats.

Examples:

• Hydroptilidae

• Chironomidae

13. Dispersal Methods

Adult Flight

Most common

Examples:

• Mayflies

• Caddisflies

• Dragonflies

Passive Drift

Larvae move downstream

Examples:

• Mayflies

• Chironomids

Resistant Eggs

Survive drought

Examples:

• Mosquitoes

14. Thermal Tolerance

Cold-water specialists

Need high oxygen.

Examples:

• Plecoptera

• Many Ephemeroptera

Indicator of good water quality

Warm-water tolerant

Can survive low oxygen.

Examples:

• Chironomidae

• Culicidae

15. Adaptations for Fast Water

Flattened body

Heptageniidae
Psephenidae

Hooks and claws

Hydropsychidae
Black flies (Simuliidae)

Silk attachment

Hydropsychidae
Philopotamidae

Suction-like attachment

Elmidae

Plastron respiration

Elmidae
Dryopidae

16. Adaptations for Desiccation

Resistant eggs

Mosquitoes
Some mayflies

Diapause

Many aquatic insects

Burrowing

Ephemeridae

Waxy cuticle

Most adults

Rapid life cycles

Mosquitoes
Chironomids

Major Order Adaptations to Remember for Exams