Demonstration Sheets for Insects (Lab 7)
All specimens this week are classified as: Phylum Arthropoda; Subphylum Uniramia;
th
Class Insecta. Page numbers are from Roberts & Janovy, 8 ed.
Order Anoplura
Pediculus humanus humanus Body louse
Notice Aclaws@ adapted for holding onto human body hair. This species is a
vector for typhus, trench fever, and relapsing fever.
12-20, Dissecting Scope
Order Anoplura
Pediculus humanus capitis Head louse
The “claws are well adapted for holding onto human head hair.
PS 3950, 4X
Order Anoplura
Phthirus pubis Crab louse
Notice Aclaws@ are well adapted for holding onto pubic hair. This species is not a
vector for human diseases.
4-13; 4X
Order Anoplura
Phthirus pubis “Nit” or Egg
Lice eggs are cemented onto strands of host hair. Since larvae literally are born
on the hosts, there is no stage in the life-cycle that is free of the host.
92W 64254-13, 10X
Order Hemiptera, Family Cimicidae
Cimex Bedbug
These organisms do not act as vectors for human diseases. Hemipterans are
recognizable by the presence of a piercing beak.
PS 4100, Dissecting Scope
Order Hemiptera, Family Reduviidae
Rhodnius Kissing bug
Vector for Trypanosoma cruzi, Chaga=s disease. Common in Central and South
America.
92W 6450, Dissecting Scope
Order Siphonaptera
Pulex irritans HUMAN-DOG FLEA
Fleas are wingless insects that rely upon their jumping ability to move from host
to host. P. irritans is usually found on dogs and can carry the plague. The species of
fleas that are adapted to the dog (Ctenocephalides canis) and cat (C. felis) lay eggs
that drop off the hosts, hatch into larvae that feed on organic material in the yard and
carpet before pupation. Thus, fleas have a free-living stage. Adults emerge from the
pupa and selectively jump onto their preferred host. If the preferred host is not
available, they will feed upon, but not infest, humans. Dog fleas are vectors for the
tapeworm Dipylidium caninum.
7-26, 4X
Order Siphonaptera
Xenopsylla cheopis ORIENTAL RAT FLEA
Fleas that live on squirrels and rats are the most important vectors for bacterial
diseases such as typhus and plague, Yersinia pestis. The bacteria multiply in the
stomach of the flea and block the gut. When the flea feeds again, the meal (and
bacteria) are regurgitated into the wound.
6-30, 4X
Order Diptera, Family Muscidae
Glossina Tsetse Fly
Vector for Trypanosoma brucei, African sleeping sickness.
P9 6841, Dissecting Scope
Order Diptera, Family Culicidae
Mosquito
Anopheles mosquitos are vectors for malaria (Plasmodium spp.) Many different
species are vectors for dog heartworm, Dirofilaria immitis. HALTERES are characteristic
for dipterans.
8-34, 4X
Order Diptera, Family Culicidae
Mosquito Heads
Only female mosquitoes take blood meals from vertebrates; thus, only females
are vectors for diseases. Males are recognized by their plumose (= feathery) antennae
containing chemoreceptors that detect mating pheromones released by females. They
feed on organic matter. Be able to recognize the difference between male and female
mosquitoes. & PS 4380; % PS 4460; 4X
Order Diptera, Family Oestridae
Gastrophilus
Horse bot fly larva
Adult females lay their eggs on the hairs of legs (G. intestinalis), under the jaw
(G. nasalis), and on the lips (G. haemorrhoidalis) of horses. They enter the digestive
system when the host licks itself. The fly larvae (i.e. maggots) live in the digestive tract
of horses acquiring nutrition of host tissues and fluids. See Fig. 39-21 and discussion
on p. 623.
Specimen; jar
Order Diptera, Family Oestridae
Horse Bot Fly
Egg on Horse Hair
This specimen was collected from a horse in Grand Bay, Alabama, 2006
Specimen, 4X
Order Diptera, Family Oestridae
Hypoderma bovis
Cattle grubs, ox warbles, heel flies
dult females lay their eggs on leg hairs of cattle. After hatching, the larvae
penetrate the skin and migrate up to the head and back to the lumbar region between
the periosteum and dura mater. Upon arriving in the lumbar region, they cut a hole in
the hide for their spiracles (i.e. breathing tubes) and feed on host tissue. They are a
significant economic pest in the United States.
Specimen, jar
Order Diptera, Family Oestridae
Cuterebra emasculator
MYIASIS
Squirrel infected with botflies or Awolves@ in local jargon. The fly lays eggs in hair.
Larvae hatch and burrow under skin where they metamorphose into a cocoon (one of
which is on display in the adjacent jar.). The opening in the skin allows the fly larva to
breathe. The larva acquires nourishment from host fluids. The bots seldom get
infected and if they are on the shoulder area, the squirrels do not seem to be hampered
by them. Eventually the larvae will leave the squirrel and pupate in leaf litter under
trees. Cats more often than dogs are sometimes infected. See Fig. 39.19, p. 621.
Specimen; jar
Order Diptera, Family Oestridae
Cuterebra emasculator
Larval fly removed from Abot@ or Awolf@ on squirrel. Infection will castrate (i.e.
emasculate) male squirrels if the bot is located on the scrotum.
Specimen
Order Diptera, Family Tachinidae
Tachinid Larva & Pupa
The very large grasshoppers or “lubbers” (= Romalea guttata) that are common
in the area serve as hosts for the tachinid fly, Anisia serotina. Locally we have found
only red-colored large immature lubbers to be infected; no parasitoids were found in
any adult lubbers (which are recognizable by their strikingly coloration). The working
hypothesis is that the fly prevents the adult metamorphosis of the host which results in
“giant” juvenile hosts. So far, no infected hosts have been collected from the MobileTennsaw Delta, while numerous infected specimens have been found near Fowl River.
Both pupae (recognizable by the “eye” on the exoskeleton) and larvae (the
segmented maggot) were found inside this host.
Specimen, jar
Order Hymenoptera, Family Braconidae
Parasitoid wasp
All species of parasitoid wasps lay eggs in larvae (i.e. caterpillar) of other insects.
The wasp larvae hatch and feed on the internal tissues of the living host. The braconid
family represented by these specimens exhibits polyembryony; i.e. two or more
individuals will develop from a single egg. The larvae that hatched inside this tomato
hornworm pupated on the surface of the host and may all have come from one egg.
The white husks are what remained of the pupae after the wasp emerged following
metamorphosis. This specimen was collected from a tomato plant in Clarke County, AL.
See Fig. 40-11, p. 634.
Specimen
Order Hymenoptera, Family Ichneumonidae
Parasitoid wasp
Al members of the family Ichneumonidae are parasitoids. They have
characteristic narrow abdomens and do NOT exhibit polyembryony. One egg develops
into one larva that becomes one adult. Those species that parasitize wood-boring
beetles, horntails, and tree wasps have extremely long ovipositors that can penetrate
bark and wood. See Figure 40-10, p. 634. Similar to the life-cycle of the heroes of the
Alien movie trilogy, these creatures acquire nutrition from the body fluids and internal
organs of their hosts who die when the wasps emerge.
Specimen
Order Hymenoptera, Family Chalcidoidae
Parasitoid wasp
A large superfamily of wasps whose larvae attack larvae of other insects. Many
are hyperparasites of other parasitoids. Members of this group are generally small. The
mymarids (not seen here) parasitize eggs of other insects and, unsurprisingly, are the
smallest insects in the world.
This specimen was donated by the curator of a “butterfly garden”, an enclosed
room allowing people to touch flying butterflies. The garden receives butterfly pupae
from “butterfly farms” in Central America. The cocoons have to be quarantined to
ensure that their parasitoids are introduced into the U.S. See Figs. 40-13 & 40-14, p.
635 & 636.
Specimen
Order Coleoptera, Family Scarabaeidae
Scarab Beetle
Members of this family that are dung beetles serve as intermediate hosts for the
pig acanthocephalan, Macracanthorhynchus.
Specimen