Female (extending out of picture) and male Linguatula serrata, commonly referred to as 'tongue worms'. Linguatula serrata adults live in the nasal passages of primarily 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.
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.
Horn Flies, Face Flies, and Stable Flies
Phormia regina A member of the family Calliphoridae, Phormia regina is an important cause of secondary myiasis, or wound myiasis with a tendency to invade not only necrotic tissue, but fresh tissue as well. Commonly known as the black blow fly, these flies are ubiquitous in the United States; times of peak activity vary by climate.
Horse Flies, Deer Flies, and Black Flies
A feeding female Tabanus melanocerus. Female Tabanids are well known blood-feeders but will also feed on honeydew and nectar as the males do. When biting a host, they cut the skin and lap up the blood that pools on the skin. This direct blood contact gives them the ability to act as a mechanical vector for many diseases. They also serve as biological vectors for Trypansosma theileri and Elaeophora schneideri.
Simulium sp. female
Simulium, also known as the "buffalo gnat," "black fly," or "humpback fly," are biting flies that swarm when they attack. There are reports of Simulium attacks resulting in the death of livestock and wildlife as a primary cause. Simulium is also known to vector various viruses such as Eastern Equine Encephalitis and Vesicular Stomatitis, along with various protozoa and nematodes such as Leucocytozoon and Onchocerca, respectively.
Simulium sp. larvae
Simulium lay their 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 equiped with a pair of brush-like organs with which they trap and ingest other insects.
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 on the ground.
Migrating first stage larvae of Hypoderma lineatum found on necropsy of a bovine. Adult female Hypoderma lineatum deposit their eggs below the hocks on the hair of cattle during the spring, the eggs hatch, larvae penetrate, and may be found around the esophagus during the winter.
Oestrus ovis larvae in the nasal turbinates of a sheep head cross section. Though the adults do not feed on animals, Oestrus is still considered parasitic as its larvae feed solely off the bodily fluids of their host. "False gid" is a condition wherein the larvae erode the bone of the skull and damage the brain, causing neurologic signs.
Keds (Wingless Flies)
Anopluran - Sucking Lice
Anopluran lice are found only on placental mammals. They feed on the blood of hosts via their piercing mouth parts, consisting of three stylets, and thus have been dubbed "sucking lice." Example genera include Haematopinus, Linognathus, Solenoptes, Polyplax, Pediculus, and Phthirus.
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 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 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.
Mallophagan - Chewing Lice
Mallophagan or "chewing lice" are found on both birds and mammals, ingesting skin, keratin from feathers or hair, and secretions of their hosts. Three suborders are described - Ischnocera (e.g. Damalinia spp.), Amblycera (e.g. Gliricola spp.), and Rhynchophthirina (Haematomyzus 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 sp. 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.
Lateral view of Demodex cati recovered from the ear canal of a domestic cat. Though usually non-pathogenic and considered normal cat flora, immune suppression may lead to overpopulation of this mite. The crusting pruritic lesions associated with D. cati demodicosis generally involves the pinnae, eyelids, head, and neck.
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 fomites.
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
Crusted lesion 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.
Ixodid (Hard Ticks)
This is a ventral view of the anterior end of a female longhorned tick or bush tick, Haemaphysalis longicornis. Note the laterally projected second palpal segments and the prominent spurs on the first pair of coxae (Specimen kindly provided by Dr. Anne Zajac, Virginia Tech).
Ixodes scapularis is known as the black-legged tick or deer tick. This tick is found in the northeastern, upper Midwest, and throughout the southern and south-central United States. Differences in host preferences for immature stages in northern and southern ranges of this tick influence the occurrence and epidemiology of anaplasmosis and Lyme disease in the United States.
Cow infested with Rhipicephalus annulatus, the one-host 'cattle fever tick.' An important vector of Babesia bovis, Babesia bigemina, and Anaplasma marginale, an eradication effort against this tick began in 1906 and by 1943, it was eliminated from the United States, outside of a small quarantined area on the USA-Mexico border.
Argasid (Soft Ticks)
Otobius megnini Nymph of Otobius megnini, the spinose ear tick. Larvae and nymphs feed in the external ear canal of ruminants and horses; these ticks are also sometimes found infesting camelids, small animals, and even humans. The adults are free-living and do not feed. Note the short spines covering the surface of the tick.