Glossary Links Lab Manual PDF
Lab 7 Appendix: Insects of Veterinary Importance

Lab Manual Appendix

Lab 1
Lab 2
Lab 3
Lab 4
Lab 5
Lab 6
Lab 7
Lab 8
Lab 9
Lab 10
Lab 11
Lab 12

Lab Demonstrations

Lab 1
Lab 2
Lab 3
Lab 4
Lab 5
Lab 6
Lab 7
Lab 8
Lab 9
Lab 10


Insects are six-legged arthropods that develop via simple or complete metamorphosis in a wide variety of ecological niches, including vertebrate animal tissue. A number or species require feeding upon vertebrate blood or tissue fluid to complete their life cycles, and some of these have evolved as more or less permanent ecto- or endoparasites of vertebrate animals, including domestic species. Insects, so evolved, have a profound impact on human and animal health as transmitters of pathogens (eg. arboviruses, malaria parasites, filariae), as agents of diseases of the skin and other tissues (eg. flea allergy dermatitis) and as sources of blood loss, annoyance and accompanying loss of production in food animals and of well-being in companion animals.

Objectives Checklist

Be able to recognize:

  1. The suborders of flies by antennal type (Nematocera, Brachycera, Cyclorrhapha) Melophagus ovinus
  2. Adult flies of the family Tabanidae
  3.  Chewing lice and the two subgroups: Amblycera and Ishnocera
  4. Sucking lice

Using a pictorial key be able to:

  1. Prepare posterior spiracles of muscoid fly larvae and make a genus diagnosis
  2. Identify flea adults to species

Lab Exercises


Suborder Nematocera (the "long-horned" flies)

Click here for a diagram of long-horned fly antennae types.

Family Culicidiae (Mosquitoes)
Mosquitoes are tiny delicate flies the females of which, in most cases, require a meal of vertebrate blood to stimulate and support egg development. Like the other true flies, developing mosquitoes undergo complete metamorphosis progressing through EGG, LARVAL, PUPAL, and ADULT stages. The immature stages are aquatic.

Simulium sp. (a.k.a. Black flies)

Simulium sp. larva
Simulium sp. adults
Simulium sp. adult head
Simulium sp.
Larva (center) and pupae (right and left). These stages are adapted to life in swift moving streams.
Simulium sp. adult
Simulium sp.
Diagram of antenna and mouthparts
Simulium sp. eggs
Simulium sp. larvae
Simulium sp. pupae
Simulium sp. (Black fly) eggs
Simulium sp.   larvae
The posterior end (to the right) would be attached to a rock at the bottom of the stream and the mouthparts on the anterior end (left) filter out food from the water column.
Simulium sp.  pupae
The filaments on the anterior end are used for breathing.

Top of the Page

Suborder Brachycera (the "short-horned flies")

This group includes the horse flies and deer flies.

Tabanus sp. - horse fly

Tabanus sp.
Tabanus sp. (Horse Fly) Adult
Tabanus sp. wing
Diagram of the short, indistinctly segmented antenna of flies in Family Tabanidae and Suborder Brachycera. Their wings have a roughly hexagonal discal cell and a branching third vein. The veins in the wings allow an entomologist to identify the fly to genus.


Tabanus sp. mouth Mouthparts of a horse fly.  The fly feeds by using its lacerating mouthparts to produce a pool of blood on the skin of its host.  The blood is then lapped up by the labium.

Top of the Page

Suborder Cyclorrhapha (the "muscoid" flies)

Musca sp. and Lucilia sp. and other muscoid flies are sometimes involved in facultative myiasis.

Click here for a diagram of the muscoid larvae spiracle characteristics.

Musca sp. adult Musca adult Lucilia adult   Lucilia sp. adult
Musca sp.  
Larvae (white)   and pupae   (brown).  
Musca larvae Lucilica larvae    Blow fly larvae
  (light brown)   and pupae   (dark brown).


Gastrophilus sp. - horses

Click here for a diagram of Gastrophilus eggs.

Gastrophilus spp. larvae
Stomach Bot Larvae
Gastrophilus spp. (Stomach Bot) Larvae
In both figures G. nasalis is on the left and G. intestinalis on the right.
Note the double row of spines on each segment of G. intestinalis and
the single row on each segment of G. nasalis.
Equine Stomach Bot Larvae in situ
Equine Stomach Bot Larvae in situ.
G. intestinalis
(left, favoring the cardiac region of the stomach) and G. nasalis (right, attached near the pylorus).

Top of the Page

Stomoxys calcitrans Adult Stomoxys calcitrans "stable fly"
Note the proboscis, which is held stright out from the head when the fly is  not feeding on a host's blood.
cow flies' locations Resting areas for various flies on cattle.

Oestrus ovis: sheep (a.k.a. Sheep Bot Fly)

Oestrus ovis larvae Oestrus ovis larvae

Cuterebra sp.: rodents, rabbits, (occasionally) dogs and cats

Cuterebra adult
Cuterebra larvae
adult Cuterebra sp.
Cuterebra larvae removed from the
subcutaneous tissues of a rodent

Hypoderma sp.: livestock

adult Hypoderma bovis
Hypoderma bovis larvae
adult Hypoderma bovis
(a.k.a heel fly or warble fly)
Note the bee-like appearance.
The mouthparts are vestigial as the adults do not feed.
Hypoderma sp. (cattle grub)
Found in subcutaneous pockets on the back of the host.
Damage to leather due to larval stages. This piece of leather is unusable and thus represents an economic loss to the rancher.

Top of the Page

Melophagus ovinus: sheep

adult Melophagus ovinus adult Melophagus ovinus Melophagus ovinus in situ Melophagus ovinus adults and pupae in the wool of a sheep. The adult females give birth to 3rd instar larvae which rapidly form their pupal cases.


Click here for Flea Identification Exercise 1 and Exercise 2

flea life cycle

adult flea
flea larva
fleas in situ
Adult flea
Flea larva
Note the gut is dark red because the larva has been eating the feces of the adult flea which contains the hemoglobin from the blood meal
Flea larvae in their natural habitat (the base of a rug).
Larva (green arrow)
Egg (yellow arrow)
Flea dirt [feces] (red arrow)

Ctenocephalides felis: cats and dogs

Ctenocephalides felis Ctenocephalides canis

Ctenocephalides felis (left)
Note the first tooth of the genal comb is as long as the second.

Ctenocephalides canis (right)
Note the first tooth of the genal comb is shorter than the second.

Click here to link to the Ctenocephalides canis (and felis) life cycle.

Echidnophaga gallinacea (a.k.a. sticktight flea): poultry

sticktight flea
Adult Echidnophaga gallinacea
sticktight flea close-up

Top of the Page


Suborder Mallophaga (Chewing Lice)

Ischnocera - Antennae stick out from head

Trichodectes canis: dogs

Trichodectes canis Trichodectes canis adult
Trichodectes canis in situ Trichodectes canis eggs and adults in the hair of a dog
Louse nit A louse egg (a.k.a. a "nit")
These are glued onto a hair shaft of the host.

Damalinia sp.: livestock

Damalinia caprae

Damalinia caprae (goats)

Notice the chewing mouthparts grasping the hair
and the easily visible 3 segment antennae

Amblycera - Antenna in pits on side of head

Menopon gallinae (a.k.a. shaft louse): poultry

Menopon gallinae Menopon gallinae adult
Menopon gallinae close-up
Head with antenna recessed into a groove on the side of the head (a characteristic of the Amblycera).
Menopon gallinae in situ
Menopon gallinae in situ

Top of the Page

Suborder Anoplura (the sucking lice)

Haematopinus sp.: swine

Haematopinus sp. Haematopinus sp.

Linognathus sp.: dogs

Linognathus Linognathus sp.

Phthirus pubis and Pediculus humanus: human (dogs and cats DO NOT act as vectors for human lice)

Pediculus humanus

Human lice

Pediculus humanus (left)


Phthirus pubis (right)

Phthirus pubis

Top of the Page



Copyright © 2008 - University of Pennsylvania School of Veterinary Medicine, All rights reserved.
Faculty: Dr. Thomas Nolan
Students: Takis Weekes V'11, Molly Church V'09, Diana Knight V'08, Douglas Gilson V'05, Chris Dykhouse V'04, Kimberly Mah V'00

Comments or Questions contact Dr. Tom Nolan at: