Download What is an insect?

Entomology
Entomology
Life Science & Study Event
2014
Forum Threads
2014
Tests
There are no images available for this event
Question Marathons
2014
This event was not held last year in Division B
This event was not held last year in Division C
Contents
[hide]





o
o
o
o
1 Description
2 What is an insect?
3 General Insect Structure
3.1 Head
3.2 Thorax
3.3 General Venation
3.4 Abdomen
4 Insect Taxonomy
5 Insect Identification (Orders Only) (Format stolen from DH's Rocks&Minerals




Page)
6 Binder Checklist
7 Resources
8 Good Links
9 Recommendations For Group Members
Description
Entomology, which is similar to the Division B event Don't Bug Me, is an event in which competitors
must be able to identify insects from 30 orders (div. B and C) and 100 families (div. C only). You should
have a good amount of knowledge on general insect information. To do well in this event, make sure
you go beyond the rules. On most tests, questions about behavior, structure, human impact, and any
characteristics of certain insects may be asked.
What is an insect?
Before getting into the specifics of identifying insects you have to know what an insect is. An insect is
an invertebrate with several distinguishing characteristics. These include: segmented bodies with
paired, many jointed legs; 3 major body sections; 6 legs; and 2 antennae. After you have identified an
organism as an insect you then must classify to its order (div. B and C) and family (div. C only).
General Insect Structure
Head
The head is the anterior oval-shaped body region that hold the antennae, eyes, and mouth parts.
Insects generally have two types of eyes, simple and compound eyes. Most have three simple eyes,also
known as ocelli, located on the upper front part of the head. Several insects lack ocelli or only have
two. Compound eyes are situated on the upper portion of an insects head and are composed of many
facets. In some insects compound eyes occupy most of the head.
The antennae are usually located on the front of the head below the simple eyes. These are great for
identification. Some of the types of antennae include aristate (are pouch-like with a bristle), capitate
(ends in a club), clavate (saw-like), filiformis (threadlike), geniculate (elbowed), monoliform (beaded),
pectinate (comb-like), plumose (feather-like shape), serrate (sawtooth shape), and setaceous
(bristlelike). See [1] for pictures.
The mouth parts of an insect are located on the ventral or anterior part of the head. The mouth part
structures typically present are the labrum (upper lip), jaw-like mandibles, jaw-like maxillae, a labium
(lower lip), and the hypopharynx which acts as a tongue. Mouth parts are generally sucking or chewing.
Insects with chewing mouth parts have lateral moving mandibles and chew their food, while insects
with sucking mouth parts have parts like a beak which is called the proboscis through which liquid is
sucked.
Diagram of head:
Thorax
This is the middle section of the body and is divided into 3 segments called the prothorax, mesothorax,
and metathorax. Each segment bears a pair of legs, and the mesothorax and metathorax usually bear a
pair of wings if the insect is not wingless. Each of the thoracic segments bear 4 groups of sclerites, or
platelike areas. These are the notum (dorsally), pleuron (there's one on each side), and sternum
(ventrally). These segments are then divided into even smaller segments.
The wings are located dorsolaterally (they're near the top) on the mesothroax and/or the metathorax.
The muscles that move wings are attached to the walls of the thorax most of the time. Insect wings
vary in number, size, shape, texture, venation, and in position held at rest making them a great assist
in identification. Most insect wings are membranous, though some are thickened or leathery. Some are
covered in hair and others in scales. Most insects fold their wings over the abdomen at rest, but others
hold them vertically over the body or hold them outstretched. Here's a picture of wing venation:
General Venation
See bottom of
http://www.cals.ncsu.edu/course/ent425/tutorial/wings.html for more.
Abdomen
The abdomen typically consists of 11 segments, but the last segment is usually represented by
appendages only. Many insects have fewer abdominal segments because of fusing of some insects. Each
abdominal segment generally contains 2 sclerites (or hardened body wall plate), a dorsal tergum and
ventral sternum. The terga usually extend down the sides of most segments and overlap the sterna.
Most insects lack appendages on the abdomen other than at the posterior end. This appendages may be
lacking or drawn into the body and hidden. When these terminal appendages are present, they usually
consist of a pair of cerci, a median dorsal epiproct (appendage above anus), a pair of paraprocts (pair
of lobes located below and on each side of anus), and genitalia. The anal opening is on the posterior
end of the abdomen, right under the epiproct. The sexes in many groups can be identified by the
genitalia at the end of the abdomen.
Insect Taxonomy

o
Kingdom: Animalia
Phylum: Arthropoda
 Subphylum: Mandibulata
 Superclass: Hexapoda
 Class: Insecta
Insect Identification (Orders Only) (Format stolen from DH's
Rocks&Minerals Page)
Insect Identification
Order Name
(nickname)
Metamorphosis
Characteristics
Insect Identification
Order Name
(nickname)
Metamorphosis
Characteristics
Protura (Telsontails)
Simple
conical head, piercing mouthparts, lacks eyes and wingless, 12 segments in
abdomen, .6-1.5mm
Collembola (Springtails)
Simple
wingless, long bodies, 4-6 abdominal segments, multicolored, tube protrudes
from abdomen, microscopic
Diplura (same)
Simple
1-segmented tarsi, chewing mouthparts, 2 cerci on head
Thysanura (Bristletails)
Simple
spindle shaped, flat bodies with 3 long, bristly tail like appendages
Ephemeroptera
(Mayflies)
Simple
distinguished easily by their two large, triangular wings
Odanata (Dragonflies &
damselflies)
Simple
two pairs of elongate membranous wings, compound eyes large, abdomen long
and slender, antennae very short
Plecoptera (Stoneflies)
Simple
4 membranous wings, elongate, flattened, cerci present, long antennae,
mouthparts chewing
Orthoptera
(Grasshoppers &
crickets)
Simple
usually 2 pairs of wings, antennae many-segmented, cerci present, has
ovipositor, FW is long, narrow, and many veined
Blattodea (Roaches)
Simple
flattened oval bodies, long laid back antennae, wings (almost never used)
Isoptera (Termites)
Simple
small, soft-bodies, usually pale-colored, antennae generally short and threador bead-like
Dermaptera (Earwigs)
Simple
slender flattened bodies, large pincers at end
Mallophaga (Chewing
lice)
Simple
bristly body, toothed mandibles, small compound eyes, abdomen more wide or
as wide as head
Anoplura (Sucking lice)
Simple
flattened and wingless, sucking mouthparts, abdomen thiner than head
Insect Identification
Order Name
(nickname)
Metamorphosis
Characteristics
Thysanoptera (Thrips)
Simple
slender bodies, short antennae, short legs, feathery wings
Hemiptera (True bugs)
Simple
FW (front wing) thickened at base and membranous at tip, HW (hind) shorter
than FW, wings held flat on body, tips of FW overlap, mouthparts sucking,
antennae of 5 or fewer segments (long and conspicuous or short and concealed)
Homoptera (cicadas and
more)
Simple
beak short and rising at back of head (different from Hemiptera), wings held
rooflike over body, tarsi 1- to 3-segmented, antennae sometimes short and
bristlike or sometimes long and threadlike
Neuroptera
(dobsonflies, lacewings,
antlions)
Complete
(finally)
FW and HW almost same size, four membranous wings, wings held rooflike over
body at rest, wings with many veins, antennae long, cerci absent, mouthparts
chewing
Coleoptera (beetles)
Complete
FW horny or leathery, FWs meet in straight line on back, HW membranous and
are usually longer than FW, wings rarely absent or reduced, antennae usually
with 11 segments (sometimes with 8-10), antennae variable in form
Mecoptera
(Scorpianflies)
Complete
slender, soft bodies; long legs and elongated, snout like heads
Trichoptera
(Caddisflies)
Complete
shaped or colored like certain moths, antennae long and threadlike, antennae
usually long as body or longer, HW a little shorter than FW
Lepidoptera (Moths &
Butterflies)
Complete
4 membranous wings, usually have proboscis in form of coiled tupe, wings
covererd in scales
Diptera (True flies)
Complete
one pair of membranous wings (you can identify them instantly from this), have
knoblike projections called haltares
Siphonaptera (Fleas)
Complete
laterally flattened abdomens, tough skin, enlarged coxae, mouthparts with 3
piercing stylets for blood sucking
Hymonoptera (Bees,
Ants, Wasps, and more)
Complete
wings are sometimes present, FW a little larger than HW, antennae usually
fairly long
Binder Checklist
*NOTE* The 2013-2014 competition only allows for one double-sided, 8.5 x 11 inches page of
information. However, previous years have allowed for a binder, so it may still be helpful to create
one for studying purposes.
Here is a binder checklist that was useful in the past: Make sure you have the following information in
your binder or known by memory: Definitely necessary:






Insect identification guide and sheets
Nymph identification sheets
Insect pictures (obviously)
Insect characteristics sheets
Human impact information
Basic insect information


Entomology glossary (to be on the safe side)
Note Sheets (for quick finding if they have a section where you
must answer questions about insects not already identified) for
the following:
Vectors
Record-winning insects (largest, smallest, fastest fliers, most
deadly, etc.)
Historical info. (safe side, horrible test making at state had at
least five questions on this subject)
Invasive species
Optional:
o
o
o
o
Resources
The following guides are highly recommended:


Audubon Field Guide to Insects and Spiders: official field guide
of the Entomology event, on which taxonomic scheme and
questions are based on, has nice colored pictures and good bug
descriptions, good for general insect knowledge; -note- this field
guide groups bugs into groups based on their basic appearance
rather than their correct phylogenetic groups (not good since the
insects in here must be ID'd according to family and order), is
also rather outdated regarding dates and population statistics
National Wildlife Federation Field Guide to Insects and Spiders &
Related Species of North America: contains close-up color
photographs with informative description, very up-to-date; note- has more than 2,000 photos of over 940 species, which may
be confusing


Peterson Field Guides: Insects - shows differences between
different insects, has all insects on insect list; -note- contains a
lot of information on how to collect and preserve an insect,
which may not be useful when preparing for this event
Smithsonian Handbooks: Insects - really nice pictures, great for
nymphs and larva identification; -note- thin and should only be
used as a supplement (the first two/three field guides are better
suited for use during the event)
Good Links


http://soinc.org/events/dontbugmeC/index.htm
http://bugguide.net



Human Impact Section
Dichotomous Key
Insect Behavior
Soon to come:
Recommendations For Group Members
Both team members should have a strong background in Environmental Science (AP Level). the team
should be prepared for both types of events (visual: power point/pictures, and live specimens), a lack
of practice in either area can result in false identifications. the teams should have knowledge in using
all types of microscopes. teams should spend a portion of their preparation, near various habitats (if
available) such as marshes, swamps, forests, grassland, etc. to observe certain native species in a
natural habitat (bring plenty of sunblock, & bug repellent)
Biological ID Events
Herpetology · Ornithology · Forestry · Entomology
Categories:


Navigation

Main Page

Forums

Image Gallery

Recent changes
Event Pages
Study Event Pages

Random page

Help
Toolbox

What links here

Related changes

Special pages

Printable version
This page was last modified on 29 September 2013, at 21:14. - This page has been accessed 21,828
times. - Disclaimers - About Science Olympiad Student Center Wiki