Review Sheet -- Test 1 (week 4) Biology 1224 B Entomology; James Adams
The SUBPHYLUM Hexapoda -- six-legged; includes the "Entognatha" and the Insecta
The "Entognatha", Apterygota, and Paleoptera -- Chapter 16,
pages 327 - 334, and Chaps.
18 - 21. The lineages covered here represent the oldest living hexapodous groups, as
well as the oldest occurring winged groups, the mayflies and dragonflies/damselflies.
Informal group ENTOGNATHA -- Chapter
Characteristics of all of the following classes/orders: all antennal segments are musculate
(if present); entognathous; mandibles with a single attachment point to the head; rudimentary
abdominal appendages, especially on front segments; spermatophore (sack containing
sperm) deposited on ground and then picked up by female (indirect insemination).
Order Protura -- Proturans (3 families in N. America; none common)
Tiny; no antennae or eyes on cone-shaped head; anamorphic (add segments with molts) --
9 segments at hatching, 12 in adult (which continues molting); soil dwelling. Front legs held
out in front, likely sensory in function (like antennae). Observed feeding has been on fungi.
Two main families in Georgia -- Eosentomidae (with a tracheal system) and Acerentomidae
(without a tracheal system).
About 500 species worldwide; found in most regions of the U.S, 20 species total from U.S.
Order Collembola -- Springtails
Tiny; with musculate antennae; unique "spring" mechanism (furca, tucked in retinaculum) in
some on six-segmented abdomen (like early myriapod larvae); live in moist, typically soil,
habitats, and are among the most important consumers in soil ecosystemes. Some live on
fungi, lower vegetation, the surface of water, and even on ice fields. May even travel by
winds. Reach adulthood by fifth/sixth instar but continue to molt. Most bisexual.
About 7000 species worldwide (even in coastal Antarctica); abundant in the U.S.
Families in GA: Entomobryidae, Hypogasturidae, Sminthuridae, Isotomidae
Order Diplura -- Diplurans (2 families possible in GA: Campodeidae and Japygidae)
Antennal segments musculate (like springtails); entognathous; no eyes; mandibles with distinct
chewing (incisor) lobe; maxillae like in insects; labial palps; 10 or 11 abdominal segments,
with rudimentary appendages on several; cerci on end of abdomen (like insects); inhabit
moist, cool habitats in soil/moss. Generalist feeders, on soil inverts, living and dead plant
and fungal matter. Bisexual, and molt throughout life.
About 800 species are known, particularly in the northern hemisphere; 60-70 species in U.S.
Subclass Pterygota --
the winged insects
Characteristics: most are winged; two attachments for mandibles to head; (10-)11 segments
on abdomen (though variable), only the last with appendages (cerci); molt only until
reaching sexual maturity and then exhibit direct insemination in most (mating).
Infraclass Paleoptera ("old wings")
Characteristics: No wing folding (can't pull wings "in"); short, setaceous antennae; wings
with lots of veins and crossveins; 10 abdominal segments; have aquatic naiads with gills.
Order Ephemeroptera ("Ephemeral wings") -- Mayflies; Chapter 20
Long slender body; non-functional mouthparts in adult (therefore short life); large forewings,
but hindwings small (occasionally absent); wings held vertically at rest; flight mechanism is
indirect; long cerci and usually median filament on abdomen; paired penes and oviducts;
unique winged subimago stage, which flies and then molts into imago. Naiads distin-
guished by muscular gills off of at least some of the first 7 abdominal segments, and the
indicated three extensions off of abdomen; naiads vary in diet (a few are predaceous).
Because of short life, often synchronously emerge in large groups. Mating in flight; female
lays lots of tiny eggs; in some species, females enter water to lay eggs. Naiads often
easier to place to family than adults, because of more selection for different feeding styles.
About 2500 worldwide, some 630 species in 16 families in the U.S. (see Table 20.1,
page 371). Common families in GA:
Baetidae - small, often with virtually no hindwings.
Ephemeridae - includes our largest species
Ephermerellidae, Leptophlebiidae, Heptageniidae, Oligoneuriidae, Caenidae,
Neoephemeridae, and Baetiscidae are the other families found in GA
Order Odonata -- Dragonflies and Damselflies; Chapter 21
Huge eyes on large, mobile head (for predaceous lifestyle -- catch other insects on the wing);
head narrowed at attachment with thorax ("neck"); only flying insects with direct flight
mechanism, with huge flight muscles; only insects to move fore- and hindwings out of phase
(makes "hovering" possible); sacrifice walking muscles (can only grasp with legs, not walk);
legs successively longer toward rear, creates basket for catching prey; long, thin, abdomen.
Male deposits sperm in secondary copulatory organ on third abdominal sternite -- in flight,
male grasps female behind head with mating claspers, then female curls abdomen up un-
derneath male to retrieve sperm ("flying in tandem"). Females dip abdomen in water to
lay eggs, either freely or on vegetation. Males often territorial and and guard spots with
potential access to mates. Males may remain in tandem until after egg laying or guard
females to ensure sperm precedence. Naiads also predaceous, with unique huge hinged,
grasping labium; can catch fish, tadpoles, etc. About 5000 species worldwide.
Suborder Anisoptera -- Dragonflies
Hold wings horizontally; hindwings broader at base than forewings; eyes allow nearly
360 degree vision. Males often defend territories. Naiads have internalized rectal gills
In U.S., @300 species in several families; common families in GA include:
Aeshnidae, Gomphidae, Corduliidae, Libellulidae, Cordulegastridae
Suborder Zygoptera -- Damselflies
Hold wings up over back (thorax tilted toward rear); fore- and hindwings similar in
shape; some males have extra "scoop" to remove previous males sperm. Naiads have
3 pairs of externalized gills near end of abdomen; some tropical species may live
in isolated water puddles and venture out at night to hunt.
In U.S., @130 species in three families: Caenagrionidae, Calopterygidae, Lestidae