Insect Taxonomy

Answer 1

Hexapod Complexity
Classification traditionally based on wing morphology
(‘Apterygotes’, ‘Pterygotes’)
Modern classification (supported by molecular study)
focusses on jaw morphology (Entognatha, Ectognatha)
Group Alternative Systems
Collembola (springtails)
Apterygota
(wingless hexapods)
Entognatha
(mouthparts retracted
within the head)
Protura (coneheads)
Diplura (two-pronged bristletails)
Archaeognatha (jumping bristletails)
Ectognatha
(mouthparts project out
from the head)
Zygentoma (silverfish)
Pterygota (winged insects) ‘Insecta

Answer 2

Ten Insect Orders
Exopterygotes = Odonata - dragonflies
(‘outside wing’) Orthoptera - grasshoppers & crickets
Dictyoptera – cockroaches, mantids, termites
Hemiptera - true bugs
Endopterygotes = Diptera - flies
(‘inside wing’) Hymenoptera - bees, wasps & ants
Lepidoptera - butterflies
Coleoptera - beetles
Apterygotes = Zygentoma - silverfish
(wingless) Archaeognatha - bristletails
We focus here on ten Ectognathous Hexapod (i.e. Insect)
Orders – there are at least 24 known Orders – but wing
morphology is important

Answer 3

Simplified Insects
Larval stage and Adult wings
No wings
(Apterygota)
Wings
(Pterygota ‘ winged insects’)
Ametabolism
No significant
metamorphosis - adults
continually moult
Exopterygotes
Hemimetabolism
Incomplete
metamorphosis
Endopterygotes
Holometabolism
Complete
metamorphosis

Question 4

Metamorphosis in the field

Answer 4

Exopterygotes= young look like a smaller version of an adult
Endopterygotes=They have different young such as larvae

Question 5

What are Apterygota and its orders?

Answer 5

Apterygota- the most ancient hexapods - two orders
Archaeognatha and Zygentoma (formerly united as the
Thysanura) distinguished via differences in mouthparts

Not a monophyletic group - retained for convenience in
grouping two orders that superficially resemble each other
and have similar life histories
Wings=(Pterygota)
No wings=(Apterygota)= Zygentoma Archaeognatha

Question 6

What is the order zygentoma

Answer 6

Order Zygentoma (Silverfish)
Dicondylous(two rotation point) mandibles place the
They are very active.
Long terminal filament and two lateral cerci held at a wide angle.
General body shape is dorsoventrally flattened (‘squashed’) & tapering to the rear; eyes small or absent.

Question 7

What are Palaeoptera?

Answer 7

Palaeoptera – Insects lacking the ability to fold their wings over the abdomen e.g dragonflies and mayflies

Question 8

Order Odonata (Dragonflies)

Answer 8

Two pairs of long, membranous (non-folding) wings; fore and hind wings are similar length.
Dragonfly eyes are closer together Characterised by large eyes and an elongate abdomen - immature instars are voracious aquatic predators

Question 9

Infra Class Neoptera

Answer 9

Insects that can flex wings over their abdomens

Question 10

Order Orthoptera (Grasshoppers & Crickets)

Answer 10

Enlarged hind legs modified for jumping; one of several “Orthopteroid” insects characterised by chewing/biting
mouthparts
In some species the male fore wings form stridulatory
organs(to ‘chirrup’) - females detect the sound with hearing
organs located the base of the abdomen or leg
A large ovipositor (used to lay eggs in cervices) is frequently apparent.
Orthoptera have a large pronotum - a plate-like structure that covers all or part of the thorax

Question 11

Order Dictyoptera (Cockroaches, mantids, termites)

Answer 11

Molecular (DNA) studies show that two suborders with
biting/chewing mouthparts belong within this Order –
although highly variable, both have a large Pronotum
Blattodea - Cockroaches have a distinctive oval body shape and pronotum that conceals the head.
Termites - soft pale body, short cerci
Mantodea (Mantids) - raptorial (grasping) forelimbs and a very
elongate pronotum

Question 12

Order Hemiptera (Bugs)

Answer 12

Mouthparts formed into an elongate beak (the rostrum) is
unique to the Hemiptera
Bed-bugs (Cimex lectularius) are a member of this Order, so
are Aphids which can reproduce asexually
These extreme modifications are adapted for piercing and sucking liquids from plant tissue, although some families are predatory.
At the centre of the rostrum are two stylets (maxillae) with grooves on their inner surface, so when placed together two
channels are created.

Question 13

Sub Class Endopterygota

Answer 13

Sub Class Endopterygota – Holometabolouslife cycle is
only common characteristic for a group covering 85% of all
Insects

Question 14

Order Coleptera (Beetles)

Answer 14

The front pair of wings are hardened into wing-cases called
elytra
Almost 40% of described insects are beetles with over
400,000 named species
Hard elytra allow beetles to burrow under the ground or into wood without wing damage
Most beetles have elytra that cover the entire abdomen but some (e.g. rove beetles) have shortened elytra that leave most of the abdomen exposed

Question 15

Order Lepidoptera (Butterflies & Moths)

Answer 15

Distinguished by the scales that cover the adult wings and
bodies
Although not a natural classification, butterflies tend to be
day flying and have clubbed antennae, while moths are
often nocturnal and with straight or plumose antennae.
Mouthparts form an elongated proboscis (nectar feeding) usually coiled under the head
Wing scales arranged like tiles to form
an extraordinary variety of colours and
patterns

Question 16

Order Hymenoptera (Bees, Wasps & Ants)

Answer 16

The hindwings are connected to the forewings by a series of
hooks.
Most species have a elongate ovipositor - modified into a sting in bees and wasps
The sawflies (Symphyta) lack the characteristic “pinched” waist shared by bees, ants and wasps (Apocrita)

Question 17

Order Diptera (Flies)

Answer 17

A single pair of functional wings; the hind wings are
modified into halteres, balancing organs used during flight
Exceptionally large and diverse Order with an estimated
million species including mosquitoes, crane flies, hoverflies
Mobile head, with a pair of large
compound eyes
Sucking mouth parts which may
also be adapted for piercing