Mink kits are attacked during the summer months when 4 to 5 weeks old.18 Fly eggs laid on the face, neck, or flanks of the kits bore into the skin and cause irritation. The Cuterebra, although rare, is a type of Bot Fly, a parasite that attacks rodents and other small mammals, including dogs, cats and rabbits. C. fontinella develops by parasitizing nutrients from its host, typically the white-footed mouse. A cat or kitten is infected by investigating burrows while hunting outdoors. A cuterebra is the larval stage of the bot fly, which is found in most regions of North America. Infestation is caused by the rodent or rabbit bot fly, Cuterebra spp (order Diptera, family Cuterebridae). Cats are accidental hosts who become infected when they come into contact with infective larvae (also known as bots or maggots). The small Cuterebra that has been removed from its tract. The fleas are found primarily along the dorsum between the shoulders and pelvis. The life cycle of this fly is as follows: The mature fly lays eggs near the nest of rabbits or rodents. Penicillin G procaine (30,000-60,000 IU/kg SC q24h for up to 5 days) may be administered to prevent secondary anaerobic bacterial infection. MSPCA-Angell West, Waltham. 2006a, Pape 2006).These flies may occasionally cause accidental myiasis in … A unique vascular disorder of the CNS, feline ischemic encephalopathy is well described in cats and thought to be related to Cuterebra larvae myasis.34,47 Affected cats typically have access to the outdoors and present in summer and early fall with unilateral prosencephalic signs, including progressive seizures, behavioral changes (often aggression), blindness, and depression. Cuterebra species can cause subdermal cysts in mustelids and have been uncommonly seen in ferrets.18 Granulomatous masses in the cervical area caused by larval stages of Hypoderma bovis are also uncommon.18 The moving larvae often can be seen through the open pore of the swollen area. Clinical signs of cuterebras are usually limited to identification of a lump or hole in the skin where the cuterebra is located; however, larvae can migrate elsewhere in the body, including the brain (feline ischemic encephalopathy), pharynx/throat, nostrils and eyes/eyelids. Genus and specific identification by simple morphological examination of larvae (bots) may be difficult to impossible, especially in younger forms. In any ferret with cutaneous myiasis, remove the larvae intact, if possible, to avoid leaving a nidus of infection or precipitating a systemic response. Either the egg hatches and the bot fly larvae burrow into the skin of the rabbit, or the eggs are picked up on the fur of the rabbit as it grazes by a plant or something else. Sarcocystis study – A new neurological disease in rabbits? For example, Cuterebra horripilum tends to seek out the throat region in cottontail rabbits, and C. fontinella commonly selects the abdominal or caudal region in the deer mouse. Cuterebra larval migration has occasionally been reported in the dog.55 Similar clinicopathologic findings have been observed. The skin around the cyst is quite dead and you might be surprised how little reaction your rabbit has to this step. More Info. This parasite can be zoonotic, so it is important to advise clients to take precautions when handling/treating affected animals. Some reports have suggested that eggs can be found in garden mulch that has been obtained near such areas. Empty warble after Cuterebra has been extracted. Cuterebra is the larva of a fly, which is embedded in the skin. The breathing hole should be gently enlarged and the larvae carefully extracted with forceps. For this reason, cuterebra are commonly found on the face, neck or even within the nostrils of cats and dogs. This is because you will be able to see moving Cuterebra right in front of your eyes. By continuing you agree to the use of cookies. Anterior chamber or penetrating foreign bodies (FB) are infrequent in dogs, cats, and horses. Ivermectin (0.2 mg/kg SC once) can be used to kill the maggots. Daily routine wound care should be provided. (617) 522-7282 Antibiotics are essential to prevent secondary bacterial infection. Kristine M. Vennen, Mark A. Mitchell, in Manual of Exotic Pet Practice, 2009. Larvae of Cuterebra species, or bot flies, commonly pupate in the rabbit subcutis but have also been reported to migrate aberrantly through the ear canals and CNS, causing neurologic signs.27 No specific clinical or clinicopathologic tests are diagnostic for cuterebriasis. Give a pet the home they deserve. More Info, 1577 Falmouth Road, Centerville, MA 02632 Fly strike, or infestation by the flesh fly (Wohlfahrtia vigil), has been reported as a problem by commercial mink and ferret ranchers and by owners who keep ferrets outdoors. Obesity, underlying dermatitis, and unsanitary conditions can predispose a rabbit to this condition. 2. The Cuterebra has been removed with hemostats. In Clinical Veterinary Advisor: Birds and Exotic Pets, 2013. Treatment requires surgical removal of the larvae. A diagnosis can be confirmed from the microscopic examination of a skin scrape or scotch tape prep. Infestation appears as a solitary, 1-cm-diameter, nonpainful, subcutaneous swelling that fistulates (larval breathing hole). Young to middle-aged indoor-outdoor cats develop acute or peracute neurologic deficits during the months from July to September.53,54, Typically, affected cats display signs consistent with a unilateral (focal) lesion involving the forebrain. The larva may be visible through the opening as it pops up to breathe but is otherwise unseen until … The lesion is usually located on the head, neck, or trunk. They do not feed nor bite. The Cuterebra has been removed and placed on a centimeter ruler. (781) 902-8400 There are 34 species of Cuterebra in North America. The lesion consists of a fibrosed tunnel with a purulent exudate. exit the host) and will continue to develop in the ground over winter until it hatches into the mature botfly in the spring. Fully-developed third-stage larvae are up to 45mm, black or dark-brown, and … Flies are a nuisance. Typically the larva enters the cat’s mouth, and then migrates to another part of the cat’s body. (978) 577-5992 Symptoms of Cuterebra in Pets. The air hole must be enlarged. Cuterebrid infection is prevented by fly control and protective screens. Treatment consists of supportive care. More Info, 400 Broadway, Methuen, MA 01844 These parasites are visible and mobile within the anterior chamber, can occasionally traverse the pupil, and infrequently enter the vitreous. Aggressive wound debridement and maggot removal are required to treat affected rabbits. The rabbit or wild rodent are the fly's normal hosts, and they can pick up these eggs on their coats and ingest them during grooming. C. fontinella has even been known to parasitize humans in rare cases. angellquestions@angell.org Blackflies of the Simuliidae family bite rabbits around lips, ears, and nares and transmit viral infections, including myxomatosis (see below).23 Bites are painful and may become inflamed. Infected rabbits generally have 1 to 5 bot larvae. Adult flies live only a short time to breed. It doesn’t Ivermectin (0.4 mg/kg SC q14days × 3 treatments) or weekly lime-sulfur dips (1 : 40) and environmental clean-up can be used to eliminate the mites. Cats and dogs are accidental hosts. flies is found only in the USA. Myiasis (botfly) in rabbits. Analgesics should be used during wound treatment to control pain. The most common victims are squirrels, rabbits, cats and dogs. C. fontinella is typically around 1 mm long with a black and yellow color pattern. Each 1- to 3-cm subcutaneous swelling encapsulates a single larva and has a breathing hole visible at the skin surface.14,22 Although some rabbits are unaffected by these swellings, others become weak, anorectic, dehydrated, lame, and in shock. Normal hosts are rabbits, squirrels, chipmunks, and mice. Parasites, such as Dirofilaria immitis in dogs, Cuterebra larvae in cats, and Setaria digitata in horses, occasionally enter the anterior chamber, cause clinical signs of anterior uveitis and variable corneal edema, and can be removed (Fig. For example, Cuterebra horripilum tends to seek out the throat region in cottontail rabbits, and C. fontinella commonly selects the abdominal or caudal region in the deer mouse. Different species of Cuterebra flies have evolved to migrate to specific anatomical locations in different hosts. The larvae hatch and make their way under the skin of the host rabbit, … The Cuterebra, or botfly, is an almost 1 inch-long parasite, which needs a small mammal to complete its life cycle.The usual hosts are rodents or rabbits. Learn about ways we provide Compassionate Access to Resources, Education and Services. Affected animals can develop severe otitis externa. Cuterebra are uncommon in dogs and cats, with the highest incidence of disease occurring during late summer and fall. Fly strike, or infestation by the flesh fly (Wohlfahrtia vigil), has been reported by commercial mink and ferret ranchers and by owners who keep ferrets outdoors.14 Mink kits that are several weeks old are most commonly attacked during the summer months. Cuterebra fontinella, the mouse bot fly, is a species of New World skin bot fly in the family Oestridae. Cuterebras and Rabbits Dr. Janice Raab DVM, CVA Have you found a new lump on your bunny? By Amanda Lohin, DVM Cheyletiella parasitovorax, an obligate, nonburrowing mite, is commonly referred to as “walking dandruff” (Figure 14-12). Lesions occur in the topography of the vasculature supplied by the middle cerebral artery (Figures 12-9 and 12-10). Hatched larvae crawl into... Dermatologic Diseases. Your cat or dog passes by the area, maybe sniffing out a mouse, and picks up the eggs on her coat. Care should be taken not to crush the larvae during extraction, as this can lead to anaphylaxis. Hyperintensities on T2W images consistent with edema may be observed in the frontal/parietal lobes. A type of myiasis (maggot infestation), Cuterebra infestations can be rather disturbing to witness on your pet. Histologic findings include parasitic track lesions, superficial laminar cerebrocortical necrosis, cerebral infarction, subependymal rarefaction, and subpial astrogliosis.146 Larvae are most commonly found in the olfactory bulbs and peduncles, optic nerves, and cribriform plate, suggesting entry from the nasal cavity.146 Treatment options are extremely limited, and most cats are euthanized because of severe neurologic impairment and aggression. Cuterebra after extraction from its warble. Latest Emergency Rescue Grant to Help the Las Vegas Rabbits. Cuterebra species can cause subdermal cysts in mustelids and have been uncommonly seen in ferrets. (617) 522-5055 The bot fly lays a single egg, either on the rabbit or on the vegetation near where the rabbits hang out. Cuterebra flies lay their eggs near rabbit runs and rodent burrows. Find yours today. May 11, 2015 . Ivermectin (0.4 mg/kg SC, ½ done in each ear) or selamectin (Revolution; Pfizer Animal Health, New York, NY) (6 or 18 mg/kg topically 1-2 times) can be used to eliminate mites.25 Do not remove the crusts or clean the ears, as the skin under the crusts is ulcerated and painful. Differentials include subcutaneous abscess and dracunculiasis. This is common to any area with livestock, manure and moisture. Dermatologic Diseases. Bot flies, of the species Cuterebra. Cleaning the environment and treating other affected animals are also required to eliminate this parasite. More Info, 293 Second Avenue, Waltham, MA 02451 A secondary skin infection can sometimes occur, in which case antibiotics may be indicated. The larvae can be diagnosed easily by the presence of a small breathing hole. Erythema and fibrosis surround the breathing hole of the Cuterebra on the body of a young cat. Cuterebra Parasitic Skin Disorders. One or both ears can be infested. angellquestions@angell.org They cause furuncular myiasis (infestation by flies) in natural rodent (mice, wood rats, chipmunks, tree squirrels, voles) and lagomorph (rabbits and hares) hosts as well as marsupials and monkeys (Colwell et al. Michael D. Lorenz BS, DVM, DACVIM, ... Marc Kent DVM, BA, DACVIM, in Handbook of Veterinary Neurology (Fifth Edition), 2011, Feline ischemic encephalopathy is a distinct syndrome of cerebral myiasis related to Cuterebra larval migration through the cerebrum.53,54 It is believed that the instar (first stage larva) gains entrance to the brain via migration through the nasal cavity and cribriform plate.54 There is no breed or sex predilection. Neurologic signs consist of seizures, unilateral blindness, circling, abnormal mental state and behavior, with contralateral postural reactions deficits, menace response deficits, and facial hypalgesia.53,54 Often affected cats display signs of acute upper respiratory disease such as sneezing or nasal discharge shortly prior (= 48 hours).53 Abnormal body temperature (hyper- or hypothermia) is observed in most affected cats.53, Presumptive antemortem diagnosis is based on clinical suspicion and MRI findings. Larvae localized in subcutaneous tissues can produce abscesslike lesions. Administer ivermectin (0.4 mg/kg SC q14d for 2 treatments) to kill larvae and an antibiotic with good skin activity, such as trimethoprim-sulfa, to treat secondary bacterial infection. Connie Orcutt DVM, Diplomate ABVP, in Ferrets, Rabbits, and Rodents (Second Edition), 2004. For rabbits that are 10 weeks of age and less than 4 kg, 0.4 ml of topical solution can be applied to the skin at the base of neck, as recommended for dogs and cats. Cuterebriasis is the medical term for infection with Cuterebra Ivermectin (0.2-0.4 mg/kg SC × 3 treatments) is the treatment of choice.4 Lime-sulfur dips and flea powder can also be used to treat affected rabbits. Passalurus ambiguous, a pinworm, is considered by some to be commensal. Removal of the larvae requires local anesthesia. My friends neighbor convinced him that this rabbit will kill me if I eat it. The wound is then allowed to heal by second intention. Debride the wound and use topical antibiotic preparations, with or without systemic antibiotics, to prevent or treat secondary bacterial infections. The fly itself does not bite, however, its larvae need live hosts to develop. Rabbits with extensive infestation may initially appear stable after surgery but then die, possibly from secondary infection of necrotic wounds with Clostridium species. The subgenus Cuterebra (comprising 12 species) parasitizes rodents, and the subgenus Trypoderma (comprising 22 species) are parasites of rabbits. Help us help cats in our community, and encourage others to do the same. A rabbit who is having trouble breathing should be checked immediately for any of these lumps. Cuterebra Attack. Cuterebra flies lay their eggs near rabbit runs and rodent burrows. 781-902-8400 In any ferret with cutaneous myiasis, attempt to remove the larvae intact so as to avoid leaving a nidus of infection or precipitating a systemic response. Cuterebra adults are flies that lay eggs near rodent or rabbit burrows. Fly eggs laid on the face, neck, or flanks of the kits bore into the skin and cause irritation, and larvae localized in subcutaneous tissues can produce abscess-like lesions. The perianal area is often affected by flystrike; the area needs to be cleaned and wound management needs to be started after the maggots have been removed. Cuterebra species can cause subdermal cysts in mustelids and have been uncommonly seen in ferrets.14 Granulomatous masses in the cervical area caused by larval stages of Hypoderma bovis are also uncommon.14 The moving larvae can often be seen through the open pore of the swollen area. More Info, 100 Littleton Road, Westford, MA 01886 Donate animal care items to our Adoption Centers! Blindness and abnormal behavior may persist. The prognosis is good, but wounds tend to heal slowly. The dog flea (Ctenocephalides canis) and cat flea (C. felis) are the most common fleas found on rabbits. Most cases occur in rabbits from poorly managed rabbitries. Introduction. Additional proposed empirical therapies include ivermectin, broad-spectrum antibiotics, and antihistamines.53 The benefit of these therapies is unproven. Copyright © 2021 Elsevier B.V. or its licensors or contributors. View all of our rewards-based training classes available. Posted on Mar 15, 2018. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Small Animal Dermatology (Fourth Edition), Ferrets, Rabbits, and Rodents (Second Edition), Ferrets, Rabbits, and Rodents (Third Edition), Surgical procedures of the anterior chamber and anterior uvea, Handbook of Veterinary Neurology (Fifth Edition), Clinical Veterinary Advisor: Birds and Exotic Pets, (Photo courtesy Jörg Mayer, The University of Georgia, Athens. Twenty-six species of Cuterebra are known to occur in the United States and Canada. Erythema and fibrosis surround the breathing hole of the Cuterebra on the neck of an adult cat. (508) 775-0940 Cuterebra is the genus or scientific family name of the North American rabbit or rodent botfly. After removal of the larvae and debridement of necrotic tissue, the swelling usually resolves. Cuterebra sp. Maggots cause extensive lesions by feeding on dead tissue.14,22 Preexisting wounds are not necessary for maggot infection. The rabbit or wild rodent are the normal hosts and can pick up these eggs on their coats and ingest them … The time period where the larvae matures to the maggot stage within its mammal host usually lasts anywhere from 3 to 7 weeks. Then these creepy little larvae travel under the skin of your pet … Once the maggot stage has been reached within the host, the maggot will “drop off” (i.e. We offer several low-cost spay/neuter programs to reduce overpopulation. FBs consisting of vegetative material are apt to also carry bacteria or fungal organisms into the anterior chamber and should be carefully removed. Cuterebra are uncommon in dogs and cats, with the highest incidence of disease occurring during late summer and fall. Mites can survive off the host for 21 days. Infestations occur more commonly in young, obese, or otherwise immunosuppressed animals. Dogs may be exposed in the same manner: by contacting the eggs as th… Bot flies are large, non-feeding flies and they tend to target small mammals (mostly rodents, including rabbits) as a host for their larvae. When you visit the veterinarian, expect to get baffled. From an online gift to a charitable gift annuity, your contribution will have a significant impact in the lives of thousands of animals. Adult Cuterebra flies resemble the bumblebee and have vestigial mouthparts. Fenbendazole (20 mg/kg PO SID × 5 days), thiabendazole (50 mg/kg PO q2 wk-q3 wk), or Piperazine (200-500 mg/kg/day PO × 2 days) can be used to treat affected animals.3,5,15, Haemodipsus ventricosus, the sucking rabbit louse, is rare in pet rabbits. Corticosteroids may help reduce the inflammatory response. Clinical signs associated with an infection include mild pruritus, large flakes of white scales on limbs and neck, alopecia, and oily dermatitis. It is most commonly observed during the hot humid summer months and during fall, and affects mainly younger animals. Posted by Adam Paudyal • 0 Comments Adam Paudyal • 0 Comments The eggs hatch into larvae and invade the dog or cat through the mouth, nasal passages, or an external wound. Cuterebra larvae develop within the tissues of certain animal hosts, and during this phase of their life cycle, they are commonly referred to as 'warbles'. The most common finding is subcutaneous lesions, which result in a raised, red lump with a central hole that is usually about 0.5 cm in diameter. Frontline (Merial Limited, Duluth, GA) should not be used on rabbits, as it can cause liver impairment. Psoroptes cuniculi is the common rabbit ear mite. Ectoparasites Breathing hole of cuterebra larvae; the larvae are sitting just under the surface and move back and forth. Noncuterebrid maggots, including those of the flesh fly, Wohlfahrtia vigil, cause moist dermatitis and matted hair around the perineum, face, and rump.18,19,23,26 Hundreds of larvae may colonize a single skin area. Purulent exudate can easily be expressed from the tract that contains the Cuterebra. The Cuterebra fly is large, somewhat resembling a large bumble bee. Psoroptes’ life cycle is 21 days. Vasospasm secondary to release of toxin produced by the parasite results in infarction in the region perfused by the middle cerebral artery or its branches.34. Five characteristic histologic features define the disease process: (1) parasitic tracks, (2) superficial laminar necrosis of the cerebrum, (3) cerebral infarction, (4) subependymal and subpial changes such as astrogliosis, and (5) identification of the parasite.54. Kirk N. Gelatt, David A. Wilkie, in Veterinary Ophthalmic Surgery, 2011. Cuterebra larvae also can migrate aberrantly from the nasal passages, eyes, sinuses, and ear canals through the central nervous system, causing neurologic signs.17,18. Bot fly larvae in the genus Cuterebra (Diptera: Oestridae) are endemic in the New World. Flies are usually host- and site-specific relative to their life cycle. Shotgun pellets generally seal their corneal wounds and appear as slightly tan areas, and do not require surgical removal. Cuterebra larvae are opportunistic parasites of dogs, cats, and ferrets. We use cookies to help provide and enhance our service and tailor content and ads. In some cases neurologic signs are preceded by signs of upper respiratory disease, including sneezing.47 Abnormal rectal temperatures, either hyperthermia or hypothermia, were noted.47, Neither routine hematology nor CSF analysis is specific for this disorder. Cuterebra (pronounced cuter-ree-brah) are larvae of the botfly who are obligate parasites to rabbits and other lagomorphs. Also, parasitic tracks may be observed extending from the cribriform plate through the olfactory bulbs and tracks. Most cases in North America occur in the late summer/early fall. Perineal dermatitis, urine scald, or skin fold dermatitis secondary to obesity may predispose to maggot infection. A cuterebra is the larval stage of the bot fly, which is found in most regions of North America. Cuterebra is commonly referred to as “warbles”. … Felines and canines serve as accidental hosts, but research suggests only by Trypoderma spp. What are cuterebra? The usual hosts are rodents or rabbits. A diagnosis can be made from a fecal flotation. 9.19). If it does not, or if the skin is abscessed, surgically excise the affected tissue. Direct visualization of Cuterebra larvae within lesion: a white, cream, brown, or black larva with stout black spines covering its body. Antibiotics may be used if the wound is large or there is a concern for systemic disease. This swelling is often confused with a ruptured abscess but will actually be housing the growing Cuterebra. Cuterebriasis is a parasitic disease affecting rodents, lagomorphs (hares, rabbits, pikas), felines, and canines.The etiologic agent is the larval development of botflies within the Cuterebra or Trypoderma genera, which occurs obligatorily in rodents and lagomorphs, respectively. Ear mites are transmitted by direct contact or contact with fomites. Larvae pupate in the subcutis, causing multiple swellings, especially over the dorsum and in the axillary, inguinal, and ventral cervical regions. Rabbits infested with maggots should be sedated to clean the affected skin, remove the maggots, and debride necrotic tissue. Sarcoptes scabiei, the causative agent of scabies, can induce a crusty, pruritic dermatitis of the face, nose, lips, and external genitalia.2 Diagnosis is via a deep skin scrape of the lesion. Gently remove the larvae through the enlarged openings, ensuring that they are not crushed, because damage to larvae can cause anaphylaxis. (617) 522-7400 The female deposits eggs near the nests of rabbits or rodents. It doesn’t take many Cuterebra to cause a problem in your rabbits. Identification and Life Cycle. Bot flies are different than regular run of the mill flies. The Cuterebra fly is a large, non-biting, fat fly that lays its eggs near rodent or rabbit burrows on grass, rocks and vegetation. Cuterebra within its warble on the neck tissue of a rabbit. It could be Warbles. angell.org/emergency Cuterebra spp. Although the intended mammal hosts are wild rodents, rabbits, etc, these ectoparasites are commonly seen in our domestic cats and dogs who sniff areas where the eggs are latent or stick their heads in rodent holes. From: Small Animal Dermatology (Fourth Edition), 2017, In Small Animal Dermatology (Fourth Edition), 2017. Cuterebriasis is a parasitic disease affecting rodents, lagomorphs (hares, rabbits, pikas), felines, and canines. Some reports have suggested that eggs can be found in garden mulch that has been obtained near such areas. This aberrant migration has been reported more commonly in cats, where clinical abnormalities tend to be progressive and include blindness, depression, and behavioral changes.54 Histopathologic changes reported in the feline suggest entry from the nasal cavity; they also point to a toxic factor elaborated by the parasite as well as potential vascular compromise.54 Could a similar pathogenesis be possible in the rabbit? The larvae encyst beneath the skin of the host and complete their development. Myiasis caused by larvae of the Cuterebra sp. Bot flies are large, non-feeding flies and they tend to target small mammals (mostly rodents, including rabbits) as a host for their larvae. Fly strike, or myiasis, is a common presentation for rabbits housed outdoors during the summer. After preparing the affected skin area for surgery, enlarge each breathing hole with hemostats. 350 South Huntington Avenue, Boston, MA 02130 Myxomatosis in the US. Treatment of subcutaneous cuterebriasis is relatively simple. emergency@angell.org The female fly lays her eggs near rodent burrows and on runways used by rabbits. Hydrogen peroxide is sometimes used (with variable efficacy) to flush the Cuterebra from its tract. MRI of the brain (Figure 27-12) may show parasitic track lesions, as well as cerebrocortical degeneration caused by toxin release by the parasite.34 Grossly, marked atrophy of the affected cerebral hemisphere can be apparent (Figure 27-13). Cuterebra – Is Your Pet Vulnerable? Related Posts. Rabbits housed outdoors should be protected against flies by means of appropriate fly traps and cage screening. Cuterebriasis is a relatively common condition that results from the migration of fly larvae through the bodies of small mammals. Email Us, 350 South Huntington Avenue, Boston, MA 02130 The animal's fur may be matted around the breathing hole as a result of the rabbit licking in reaction to the pain associated with the larvae. The story begins with the Cuterebra fly, a large fly that doesn’t bite but loves to lie its eggs on vegetation or rocks that are right next to a rabbit … However, the eggs or hatched larvae can stick onto a dog or cat if they pass by. The most important aspect of treatment is removal of the larva/maggot. Snow comes in to see Dr. B because of flees and mysterious bumps on her side. Cuterebra is the scientific name of the North American rodent botfly. The life cycle of the fly requires migration through the soft tissue (muscle, fat, skin) of the animal, followed by a prolonged period of development to the maggot stage within a “warble” in the skin (a pocket created under the skin with a little air hole by the larva as it develops into a maggot).