Cimex lectularius

Cimex lectularius is commonly known as the bed bug. Bed bugs have a painful bite that can annoy humans and animals alike. Although blood feeders, they historically have not been considered major disease vectors. However, recently bed bugs have been shown to transmit Trypanosoma cruzi in an experimental setting. It is currently not known what role bed bugs play in the epidemiology of the hemoflagellate.

Order Orthoptera

​Triatoma spp.

Pentastomes

Armillifer armillatus
Adults of Armillifer armillatus in a Chinese Viper lung. Nymphal stages of this tongue worm occur in the inner organs and musculature of a variety of species including humans and rodents. The calcification of encysted nymphs are often observed in radiographs.

Linguatula serrata
Female (top) and male Linguatula serrata, commonly referred to as 'tongue worms'. Linguatula serrata adults primarily live in the nasal passages of canids, but may also be found in humans, horses, and ungulates. Pathogenesis is similar to that of the nasal bot, with irritation and nasal discharge being the greatest clinical signs. ​

Linguatula serrata
Transverse section of the nasal cavity of a dog revealing a Linguatula serrata dorsal to the hard palate in the ventral nasal meatus. Adult pentastomes are most often found in carnivorous reptiles, but may be found in a diverse array of other vertebrates.

Pentastomid
A pentastomid egg found on fecal flotation. Eggs of are large, measuring over 100 μm, and are often surrounded by a capsule. Note that legs bearing hooklets are visible on the larva within the egg. Ingestion of these eggs is the source of infection for intermediate hosts.

Pentastomid
Removed from the lungs of a Gaboon viper (Bitis gabonica), this pentastomid is suspected to be Armillifer armillatus. There are at least 130 species of pentastomids. All are obligate parasites of vertebrates and adults are found in the respiratory tract.

Pentastomid
Pentastome nymphs in a fish. Most human cases of porocephalosis (a generic term implying any pentastome infection) are a result of the ingestion of undercooked fish

Porocephalus crotali
Nymphs of Porocephalus crotali in the mesenteric lymph nodes, omentum, liver, subserosa of the small and large intestines, mesentery, and lungs of a dog. Nymphal development of pentastomes occurs in the intermediate host.

Cediopsylla simplex

Cediopsylla simplex, the rabbit flea

Ctenocephalides felis

The cat flea (Ctenocephalides felis) is the most common flea of both dogs and cats. A new generation of fleas can hatch and begin producing eggs in as little as 3 weeks.

A close view of the genal ctenidia ('combs') of Ctenocephalides felis. Identification of different fleas is based primarily on ctenidia and ocular bristles.

A group of adult Ctenocephalides felis. Ctenocephalides felis serves as an intermediate host for Dipylidium caninum and also vectors several other disease agents.

A dog severely infested with Ctenocephalides felis as evidenced by the large amount of dried blood commonly referred to as “flea dirt” visible on the skin.

Pupae of Ctenocephalides felis

Echidnophaga gallinacea

The sticktight flea (Echidnophaga gallinacea) is most often found on domestic and wild birds. Occasionally this flea will infest cats and dogs. Note the characteristic angular head and compressed thorax.​

Adult sticktight fleas (Echidnophaga gallinacea) on a Victorian pigeon. Adults burrow into the combs, wattles, and around the eyes of birds, feeding and laying their eggs into the dermis. Once the eggs hatch, the larvae fall out and develop in the environment.

Nosopsyllus fasciatus

Nosopsyllus fasciatus, the northern rat flea

Orchopeas howardii

​Orchopeas howardii, the squirrel flea

Pulex irritans

Pulex irritans is the human flea, but species of Pulex infest a wide range of wild and domestic animals. The ocular bristle is a key identifying feature of this genus.​

​Closeup of Pulex irritans highlighting the occular bristle which originates below the eye.

Xenopsylla cheopis

Xenopsylla cheopis, the Oriental rat flea is an important vector of Yersinia pestis, the agent of plague. Rats are the preferred host but Xenopsylla cheopis will infest numerous other animals include dogs, cats, and chickens.

Closeup of Xenopsylla cheopis highlighting the ocular bristle which originates in front of the eye.

Sandflies

Phlebotomus sp.
Genus of sand flies that vector Leishmania in Europe, Africa, and Asia.

Lutzomyia sp.
Lutzomyia feeding on a spiny lizard (Sceloporus sp.). Lutzomyia is a vector for Leishmania spp. and vesicular stomatitis virus in the Americas.

Biting Midges

Culicoides sp.
Because of their small size, Culicoides or biting midges are often called no-see-ums. Even so, they have a painful bite, causing considerable annoyance to human and animal hosts. Horses often become allergic to the bites. Culicoides sp. also serve as a vector of bluetongue virus

Culicoides hypersensitivity
Sweet itch, Queensland itch, seasonal recurrent dermatitis, and summer itch are all common names for a condition in horses caused by hypersensitivity to the saliva of Culicoides sp. Common affected areas include the tail head, mane, ears, and ventrum. Alopecia occurs secondary to pruritus.

Mosquitoes

Aedes sp.
Aedes mosquitoes are important vectors of heartworm (Dirofilaria immitis) and several viruses important in veterinary medicine and public health.

Anopheles sp.
Anopheles are important vectors of human malaria throughout the world.

Culex sp. Magnified view of the head of a male culicine mosquito. Culex is an important vector of many diseases including West Nile virus and avian malaria.

Horn Flies, Face Flies, and Stable Flies

Haematobia irritans
Although it is known as the horn fly, H. irritans can be commonly found on the backs of cattle. In addition to annoyance, they serve as a vector for Stephanofilaria stilesi.

Haematobia irritans
Dorsal view of the horn fly. The majority of a horn fly's adult life is spent on its host, leaving only briefly to oviposit in fresh manure piles.

Musca autumnalis
Adults of Musca autumnalis, an important vector for pink eye (Moraxella bovis)

Musca domestica
The common house fly, Musca domestica, is a mechanical vector of many infections and is a biological vector for Draschia megastom a and Habronema muscae.

Musca domestica
Four black stripes along the thorax of this fly aid in identification.

Phormia regina
A member of the family Calliphoridae, Phormia regina is an important cause of secondary or wound myiasis with a tendency to invade both necrotic and fresh tissue. Commonly known as the black blow fly, these flies are ubiquitous in the United States; times of peak activity vary by climate.

Stomoxys calcitrans
The stable fly is recognizable by its emarginated eye and distinct proboscis which projects forward. Although usually associated with cattle and horses, this fly may occasionally be found feeding on dogs and is also known as the dog fly or kennel fly.

Stomoxys calcitrans
Adult Stomoxys calcitrans prefers to feed on the distal limbs of cattle. However, most of their time as adults is spent elsewhere in the environment. Stable flies reproduce in piles of decaying organic matter.

Horse Flies, Deer Flies, and Black Flies

Chrysops sp.
Female Chrysops ovipositing on a blade of grass above water. Female deer flies feed on the blood of hosts and serve as important mechanical vectors for pathogens as well as a source of discomfort and loss of production for livestock.​

Hybomitra hinei
A member of the family Tabanidae, Hybomitra hinei has been recorded as one of the fastest flying insects with a reported speed of 145 km/h. Tabanids are thought to use polarized light to orient and horse flies are active only during daylight hours.

Tabanus americanum
Tabanus americanum may be distinguished from other horse flies by its antennae. The first two segments are distinctively short, while the terminal segment has a tooth like projection at the base.

Tabanus lineola
Known as the striped horse fly, Tabanus lineola is more commonly found in the eastern and southern United States, though it is not limited to this range. Tabanids hold their wings horizontally when resting, as shown.

Tabanus melanocerus
A feeding female Tabanus melanocerus. Female Tabanids are well known as blood-feeders but will, like males, also feed on plant fluids. When feeding on blood, they cut the host skin and then lap the pooled blood. Horse flies serve as mechanical vectors for many pathogens and as biological vectors for Trypanosoma theileri and Elaeophora schneideri.

Simulium sp. female
Simulium spp., also known as black flies, buffalo gnats, or humpback flies, are biting flies that swarm when they attack. There are reports of Simulium sp. attacks resulting in the death of livestock and wildlife. Simulium is also known to vector viruses (e.g. Eastern Equine Encephalitis, Vesicular Stomatitis), protozoa (e.g. Leucocytozoon sp.), and nematodes (e.g. Onchocerca spp.).

Simulium sp. larvae
Simulium spp. females deposit eggs on stones or plants just below the surface of the water in running streams. The eggs hatch in 4 to 12 days and the larvae attach themselves to rocks by means of a posterior organ that is armed with small hooks. Their anterior is equipped with a pair of brush-like organs with which they trap and ingest other insects.

Myiasis

Cutaneous myiasis
Post-docking cutaneous myiasis in a lamb. This condition is commonly known as "fly strike" or "fly blown" to producers. Genera of facultative myiasis flies include Musca, Calliphora, Phaenicia, Lucilia, Phormia, and Sarcophaga.

Cochliomyia hominivorax
The pigmented tracheal trunks of larval Cochliomyia hominovorax , primary screwworm, allow it to be distinguished from larvae of Cochliomyia macellaria , secondary screwworm.

Bot Flies

Cephenemyia sp.
Nasal bots of white-tailed deer, Cephenemyia can be found in the retropharyngeal space.

Cuterebra sp.
Severe infestation of Cuterebra in a vole. Adult Cuterebra deposit their eggs near the entrances of burrows belonging to potential hosts.

Cuterebra sp.
Larval Cuterebra sp. encysted in the neck of a cat. Infections of the cranial cavity of the cat have been reported as well as parasitic orchitis in both dogs and cats, and dermal cysts in humans.

Dermatobia hominis
Larval stage of Dermatobia hominis in the skin of a person. Infections with the human botfly are most commonly reported from Central and South America. Development in the host requires five to ten weeks.

Dermatobia hominis
Extraction of Dermatobia hominis from the back of a bovine. The posterior end of the larva may be seen protruding through the hole it has cut through the dermis. Dermatobia hominis may infect cattle, dogs, cats, sheep, rabbits, and other animals including humans.

Dermatobia hominis ​
Larva of Dermatobia hominis. A member of the family Cuterebridae, Dermatobia hominis is found in tropical America, from Mexico to the Argentine. Adults lay eggs on the abdomens of biting flies which provide transportation as well as initial access into the dermis.

Gasterophilus sp.
Species of Gasterophilus can be differentiated according to patterns of spines on the bot larvae.

Gasterophilus sp.
Section of horse stomach infected with bots. Larvae tend to cluster together on the the non-glandular portion of the stomach, near the margo plicatus.​

Gasterophilus nasalis
Migrating first stage larvae of Gasterophilus nasalis around the molar of a horse. First stage larvae will migrate for approximately 28 days before molting and moving to the stomach.

Gasterophilus sp.
Egg of a Gasterophilus sp. on a horse hair. A single female horse bot fly can oviposit between 150 and 1000 eggs on a horse, typically during the early summer months.

Hypoderma sp.
Like all bot flies, adult Hypoderma are non-feeding, as evident by their diminished mouth parts. Adult bot flies live only one to two weeks, allowing enough time to mate and oviposit.

Hypoderma sp.
Nodules on the backs of cattle caused by encysted Hypoderma larvae, said to be in the, 'warble' stage. The larvae cut small holes or pores in the backs of cattle through which they respire. This stage lasts approximately 30 days before the larvae emerge through the pores and begin pupation in the soil.

Hypoderma sp.
The third-instar of Hypoderma can be found in subcutaneous nodules in the backs of cattle.

Hypoderma lineatum
Migrating first stage larvae of Hypoderma lineatumlarvae. Adult female Hypoderma lineatum deposit eggs below the hocks on the hair of cattle during the spring. The eggs hatch, larvae penetrate, and begin to migrate through the host. Larvae of H. lineatum may be found around the esophagus during the winter.

Oestrus ovis
Oestrus ovis larvae in the nasal turbinates of a sheep head cross section. "False gid" is a condition wherein the larvae erode the bone of the skull and damage the brain, causing neurologic signs.

​Keds (Wingless Flies)

Melophagus ovinus ​
Melophagus ovinus is the sheep ked. This wingless fly is most often confused for a louse and is sometimes called the louse fly.

Anopluran - Sucking Lice

Anopluran lice
Adult lice and nits of the suborder Anoplura as seen on their host.

Haematopinus sp.
A genus of sucking lice that infests pigs, cattle, horses, and other species.

Haematopinus sp.
Nits (eggs) attached to hairs.

Haematopinus eurysternus Also known as the short-nosed cattle louse, Haematopinus eurysternus is considered to be the most economically important louse of cattle. They are usually found on the top of the neck, base of the horns, brisket, and tips of the ears, but may be found anywhere when an animal is heavily infested.

Haematopinus suis
Haematopinus suis adults feeding on a pig. The largest species of louse to infect domestic animals, Haematopinus suis, or the hog louse as it is commonly known, is an obligate ectoparasite of wild and domestic swine. A known carrier of Swine Pox, the hog louse is associated with intense pruritis and often confused with mange.

Haematopinus quadripertusus
Haematopinus quadripertusus nymphs on the vulva of an adult cow. Haematopinus quadripertusus adults are found almost exclusively in the hair at the end of cattle tails, lending their common name the 'tail-switch louse.' They lay their nits on tail heads and switches. Upon hatching, nymphs migrate to the soft skin around the anus, vulva, and eyes. Once they molt, they migrate one more time back to the tail switch.

Linognathus sp.
A genus of sucking lice that infests sheep, cattle, and dogs.

Pediculus humanus
Pediculus humanus is comprised of two subpecies, Pediculus humanus humanus (body louse) and Pediculus humanus capitis (head louse).

Polyplax spinulosa
A common louse of rats, Polyplax spinulosa, or spined rat louse, can be found on domestic, laboratory, and wild rats. It is a biological vector for Haemobartonella muris in addition to causing host pruritus and alopecia.

Phthirus pubis
Known as the pubic louse or crab louse, Phthirus pubis infests only humans. Lice are extremely host specific and Phthirus pubis is not known to survive and reproduce on pets or other animals. A related species, Phthirus gorillae, has been described from mountain gorillas.
Photo by Brian Herrin, Kansas State University

Solenopotes capillatus
Also known as the little blue cattle louse, Solenoptes capillatus is preferentially found on the face and jaw of captive ungulates, namely cattle and gazelles. They are spread through direct contact.

Mallophagan - Chewing Lice

Damalinia bovis
A common chewing louse of cattle is Damalinia bovis. They may be found in greater numbers on cattle during the winter and early spring when cattle are in closer proximity and have longer hair coats. ​

Damalinia caprae
The most common louse of goats, Damalinia (Bovicola) caprae preferentially inhabits the lumbar area and back of shorter haired goats.

Damalinia caprae
Adults (blue arrow) and nits (black arrow) of Damalinia (Bovicola) caprae on the back of a goat.

Damalinia equi
The chewing louse of horses, Damalinia (Bovicola) equi has a predilection for the neck and tail head. Outbreaks are more likely to occur during the winter time and clinical signs include pruritus, alopecia, and scaly skin.

Felicola subrostrata
The chewing louse of cats. This louse is easily recognizable because the head is triangular-shaped.

Menopon sp.
Genus of chewing lice commonly found on birds.

Trichodectes canis The canine biting louse is about 1.5 millimeters in length and can be visualized without magnification.

Trichodectes canis
Cleared specimen of adult Trichodectes canis.

Trichodectes pinguis
Adult Trichodectes pinguis, the chewing louse of black bears.

​Cheyletiella spp.

Cheyletiella spp. are surface dwelling mites that are distinguished from other mites by their large palpal claws. Ventral view of a Cheyletiella sp. mite recovered from a cat. The large palpal claws and enlarged gnathosoma seen on the anterior portion are very characteristic of this mite. Cheyletiella spp. do not burrow, but do feed on the lymph and tissue fluids.

An egg of Cheyletiella. All developmental stages of Cheyletiella occur on the host. Eggs are glued to hairs loosely and may be ingested by the host and passed in the feces. Though this mite may live off of the host for up to 10 days, transmission is usually through direct contact between parent and offspring.

Chorioptes spp.

Chorioptes spp. infest a variety of animals including cattle, horses, and rabbits.​

Infestation with Chorioptes bovis on dairy cattle may result in a mild dermatitis on the back of the udder. Other locations where lesions commonly develop include the tailhead, feet, and legs.

Leg of a female Chorioptes. The cause of chorioptic mange in several species of domestic mammals, Chorioptes spp. have unjointed pedicels extending from their leg to tarsal suckers. These suckers occur on all of the legs on the male, and on leg pairs 1, 2, and 4 on the female.

Ventral aspect of a male Chorioptes bovis. Chorioptes bovis may infest horses causing foot mange, an intensely pruritic condition to which horses with long hair on their fetlocks are particularly susceptible.​

Demodex spp.

Demodex sp. mite ​
Demodex spp. are elongated mites found in sebaceous glands and hair follicles of their respective hosts. Transmission is generally direct from dam to offspring during the neonatal period.

Demodex canis
Demodex canis found in the skin scraping of a dog. Demodex specimens may also be seen on fecal flotation if pruritic animals ingest the mites while grooming.

Demodex caprae
in a skin scraping from a goat with severe demodicosis. Goats with demodicosis present with multiple nodular skin lesions on the face, neck, axillary region, and/or udder.​

Demodex cati
Lateral view of Demodex cati recovered from the ear canal of a domestic cat. Though usually non-pathogenic and considered natural flora of cats, immune suppression may lead to overpopulation of this mite. The crusting, pruritic lesions associated with D. cati generally involves the pinnae, eyelids, head, and neck. ​

Demodex gatoi
Demodex gatoi, another common Demodex sp. mite on cats, is found more superficially than Demodex cati and is often removed during grooming and thus not recovered on skin scraping. Instead, this mite is most commonly found in fecal flotations.

Dermanyssus spp.

Dermanyssus mites are frequently found on both domestic and wild birds. These mites occasionally invade dwellings and bite people and pets; the source is usually an abandoned nest nearby.

Eutrombicula spp.

Classified as a chigger mite, Eutrombicula may infest domestic mammals and produce a syndrome referred to as trombiculosis, characterized by pruritic skin papules or crusty eruptions.

Harpirhynchus

Ventral view of Harpirhynchus, a mite of the brown cowbird (Molothrus ater). Little is known about these mites, but they seem to burrow beneath the cowbird's skin and form cysts.​

Cysts on a brown cowbird formed by Harpirhynchus sp. The cysts are filled with mites, keratin, and cellular debris.​

Knemidokoptes spp.

Knemidokoptes, also known as the scaly leg mite, burrow under the scales of the non-feathered areas of birds. Infestations can lead to disfigurement and death of the birds.

Ventral and dorsal view of Knemidokoptes mutans. To collect and diagnose infestation of this mite, skin scrapings should be taken from the periphery of lesions.

A budgie infested with Knemidokoptes, with characteristic scaly proliferative lesions on the non-feathered portions of the face. The burrowing of the mite causes the integument to exude a serous fluid that hardens into a crust. Birds acquire the mites through direct contact with other infested birds or with contaminated fomites.

Notoedres cati

Ventral aspect of Notoedres cati collected from a cat. Notoedres can be differentiated from Sarcoptes by the presence of a dorsal rather than a terminal anus, and prominent rounded scales on its dorsum as opposed to the pointed scales found on Sarcoptes sp.

Lesions of Notoedres cati in a rabbit. Although usually found on cats, this mite may also infest rabbits. Infestations may begin on the ears and back of the neck and extend to the face and rest of the body.

Ophionyssus natricis

Ventral view of Ophionyssus natricis, a blood feeding mite of captive reptiles. These mites may be found under the scales of several species of snakes and lizards, notably around the rim of the eye. Heavy infestations lead to anemia, presenting as listlessness, and may lead to death.

Oribatid Mite

Scheloribates laevigatus
An oribatid mite, Scheloribates laevigatus, is considered the most efficient intermediate host for Moniezia throughout the world.

Ornithonyssus spp.

​Ornithonyssus mites infest birds in temperate, tropical, and subtropical areas.

Ornithonyssus sylviarum
Ornithonyssus sylviarum, known as the northern fowl mite, on the head of a chicken. Found in temperate regions worldwide, this mite can be seen on the skin among feathers, often concentrating around the vent, causing a dark discoloration.

Otodectes cynotis

Otodectes cynotis infests the ear canals of primarily dogs and cats.

Psorobia ​sp.

Dorsal view of a species of Psorobia. The most economically important member of the Psorergatidae family is Psorobia ovis. Known as the sheep itch mite, Psorobia ovis infests domestic sheep, causing pruritus, wool loss, dry scruffy skin, and erythema. Merinos are considered to be especially susceptible. Similar to Demodex, Psorobia mites live in hair follicles

Psoroptes spp.

Infestation of Psoroptes cuniculi in the ears of rabbits can produce a large amount of serum and hyperkeratotic crusts inside the ears.

Adult female Psoroptes cuniculi collected from a goat ear swab. Psoroptes cuniculi may be found on rabbits and ruminants. Other species of the same genus may be found on horses and wildlife.

Crusted lesions from Psoroptes cuniculi infestation in a goat. Lesions consist of exudative dermatitis and hair loss, often beginning in the ear and spreading to the head and neck. The mites live superficially on the skin surface and are easily collected with a superficial skin scraping or scabs that have been broken apart.

Lesions from Psoroptes ovis on the ventrum of a sheep. Once of considerable economic importance as the cause of psoroptic mange in ruminants, Psoroptes ovis has been eradicated from domestic sheep in many areas of the world.

Raillietia auris

Dorsal view of Raillietia auris. This mite lives in the ear canals of domestic ruminants and has been associated with Mycoplasma sp. and otitis externa.

Sarcoptes scabiei

Sarcoptes scabiei is a small, round mite that burrows in the skin of domestic and wild animals. Note the long, unjointed pedicels extending from the legs, terminating in suckers.

Infestations with Sarcoptes scabiei can produce a severely pruritic, erythematic dermatitis with alopecia, hyperkeratosis, and crust formation.

The intense pruritus experienced with scabies is due to the mite burrowing into the dermis to lay eggs, molt, and feed on young epidermal cells and lymph. In some animals, lesions severely encrusted with coagulated exudate may occur with or without pruritus, a condition known as crusted scabies. ​

Trixacarus caviae

The sarcoptiform mite of guinea pigs. Clinical cases present with widespread alopecia, intense pruritis, keratization, and occasionally seizures. A key identifying feature of this mite is the long, unsegmented pedicels on leg pairs 1 and 2 terminating in suckers.