What are Reptile Mites?
Mites belong to a large group of animals known as Arthropods. As a group they are characterised by having hard, segmented bodies bearing jointed limbs. They contain the largest known number of animals including the crustaceans (e.g. crabs, lobsters and shrimps), insects and arachnids (e.g. spiders, scorpions, ticks and mites). The Arachnid group can be further broken down into separate Orders of animals. One of these Orders is called Acarina and this group contains all the different mite species. Mites are characterised by their minute size, transparent or semitransparent bodies, fused head, thorax and abdomen and their abscence of antennae and mandibles (lower jaws).
The correct scientific term used to describe an infestation with mites is Acariasis and it has been reported in both captive and wild reptiles. In captivity however parasite numbers can reach staggering proportions. This is because captive reptiles can be subject to crowding, unhygienic conditions, starvation and other poor husbandry factors. These in turn can expose a captive reptile to environments that are extremely favourable for mites to multiply. In addition to this, captive reptiles are unable to escape the parasite burdens as a wild reptile would be able to do because of their confinement.
There are over 250 different species of mites that have been reported to parasitise reptiles. By far most common of these is the blood sucking snake mite, Ophionyssus natricis. It normally infests snakes but can also be found in captive lizards. For this reason, along with the fact it the most common species of mite seen on reptiles, the terms snake mite and reptile mite are often used interchangeably. Mites are easily drowned so aquatic reptiles such as turtles and crocodiles are very rarely affected.
Why are Reptile Mites a Problem?
Reptile mites not only look bad on snakes and lizards but they can cause some serious health problems. They can cause irritation, inflammation, problems with shedding (dysecdysis) and secondary bacterial infections of the skin.
In heavy infestations on young or small snakes and lizards the mites may consume a large enough quantity of blood that they can cause a potentially life-threatening anaemia and immune suppression. Mites have also been implicated as a mode of transmission of various infectious agents. These included Aeromonas hydrophilia, a common bacterium that causes pneumonia and infectious stomatitis (mouth rot) that can lead to septicaemia and death; viruses such as those causing Inclusion Body Disease (IBD) and Ophidian Paramyxovirus (OPMV); and parasites of the red blood cells and the blood stream.
Large numbers of mites can potentially cause interference with the heat sensing pits in pythons. There have also been reported cases of certain species of snakes actually developing allergies to the mites saliva.
Although snakes mites do not generally affect people there have been reports of humans developing dermatitis following exposure to the mites.
The Reptile Mite Life Cycle
The life cycle of the reptile mite consists of five stages: egg, larvae, protonymph, deutonymph and adult.
The eggs are laid as a sticky cluster on the inner surface of protected areas within the enclosure. They are off-white to tan in colour initially and as they mature towards hatching they develop a dark end. While they can be seen with the naked eye they are very small with unfertilised eggs being smaller than fertilised ones. Interestingly the speed at which the eggs develop is temperature dependent and doubles with each 5C increase between 20C and 30C. At 25C eggs will hatch within 40 to 50 hours.
Larvae are small, white and have three pairs of legs. They do not feed and generally remain at their hatch location until they moult to the next stage. At 25C to 30C the larval stage only lasts 18 to 24 hours. If conditions are too dry this moulting cannot occur and the larvae will die.
The protonymph stage has 4 pairs of legs and is an aggressive blood sucker. They congregate on items in the enclosure and swarm when there is any disturbance. While they can live for up to 31 days without feeding they generally locate a reptile host quickly and crawl under the scales, particularly around the eyes and head where the skin is generally softer and thinner. Over the next 3 to 7 days the protonymphs will engorge themselves on blood, changing colour from white to red as they do so, before dropping off the host and taking shelter under rough, dark surfaces. In 12 to 48 hours they moult and develop into the deutonymph stage. About 10% of protonymphs get caught in their old skin when they moult and die.
Deutonymphs are active, non-feeding stages that are dark red to black in colour. This stage only lasts 24 to 26 hours at 25C before a final moult into adulthood. They are normally found on cage furniture and the cage itself but seldom on the actual reptile host. Deutonymphs that are to become males are often found riding on the backs of female deutonymphs in preparation for mating. Like the protonymph stage about 10% become trapped in their old skin at the time of mating and subsequently perish.
Adult reptile mites are very active and will seek out a host to feed on constantly. Once attached they engorge on blood over the next 4 to 8 days. They develop a dark red to black colouration. The variation in colour is dependent on the density of the blood ingested and the amount of digestion that has occurred. A female mite can ingest up to 1500% of her body weight in the hosts blood with each feeding. They feed two to three times at one to two week intervals. Male mites do also feed on blood but are smaller than the females.
Each time the female mites have finished feeding they tend to crawl upwards looking for a dark, moist and protected area to lay their eggs. They lay about 20 eggs in a sticky cluster.
Female mites will only mate after the first feed and mating is dependent on body size. Once a female weighs greater than 0.15 milligrams males are no longer attracted to her.
Mated female mites lay both fertilised and non-fertilised eggs. The fertilised eggs develop into females and the non-fertilised eggs developed into males via a process called parthenogenesis.
With the right conditions adult reptile mites can live up to 40 days with or without feeding.
The entire life cycle can be completed in as little as 7 to 16 days depending on temperature and humidity. This means that a large population of mites can develop very quickly. It is important to realise that other than when the protonymph and adult stages are feeding the majority of the reptile mites life cycle is OFF the host reptile. This has significant implications when the treatment of mite infestations is considered.
Reptile Mite Biology
Environmental factors such as temperature, humidity and light play a huge role in the activity and behaviour of reptile mites. An appreciation of this will go some way to understanding the best methods of eliminating them.
Reptile mites will assemble in areas where the temperature is between 20C and 23C. The rate of movement of the mites is directly related to temperature with increased activity at higher temperatures. When mites are exposed to temperatures between 20C and 23C they move in a relatively straight line. When they are exposed to temperatures higher than this they will turn and try and locate an area of suitable temperatures. If the temperature falls below 10C all stages of the mites life cycle become unable to move but are not necessarily killed. At temperatures above 50C all stages of the reptile mite life cycle are killed.
Humidity greatly affects the hatching and moulting success along with the mites behaviour. While they prefer areas of high (95%) humidity they are very easily drowned in single drop of water! Because mites prefer humid conditions tropical reptile species such a Green Tree Pythons and Jungle Pythons are good candidates for mite infestations.
Reptile mites can distinguish between various smells using smell receptors on their legs. They are attracted to a live snake but not a dead one. They cannot tell the difference between snake blood and frog blood. They can tell the difference between snake blood, snake faeces and snake skin. The mites are not afraid of heights and prefer to move upward. They will climb rather than go around an object and when they reach the top of something they will generally stop.
Interestingly, for a reptile mite to feed, part of its head must be covered and in contact with something from above. This is why they attach under the scales of their host. If the skin of the animal is stretched so that the scales do not overlap the mites cannot feed and will ultimately starve to death! This is also the reason why smooth scaled reptile species such as Geckos are at low risk of mite infestation.
Light also greatly affects reptile mite behaviour. Mites move in a straight line in darkness but when exposed to light they turn and seek a darker area.
Adult mites can travel a surprising distance if conditions are suitable. It has been suggested they can move 2 to 3 metres up and out of enclosures if possible. It is therefore possible for them to move from one enclosure to the next thereby spreading the infestation.
Diagnosis of a Reptile Mite Infestation
The diagnosis of a reptile mite problem is normally relatively straight forward because in most cases the mites can be seen on the animal. The use of magnification can aid in finding mites, particularly in the areas around the eyes, the gular fold (the fold of skin under the chin area in snakes), the heat sensing labial pits along the lower jaw in pythons and the ears and armpits of lizards. Any unusually positioned scales should also be closely examined to ensure there is not a mite lodged in underneath it.
If a mite infestation is suspected the animal can be laid on a large sheet of white paper and using a small brush, gauze swab or oil-soaked cotton swab the snake or lizard can be brushed or rubbed down to see if any mites can be dislodged. Alternatively the reptile can be placed in white pillow case and allowed to move around and free any attached mites.
In some case, particularly in lizards, full thickness skin scrapings or skin biopsies may be required to make a diagnosis.
In addition to finding live mites, their faeces can often be seen as white specks on the scales. This is often referred to as mite dust.
Affected reptiles may show a variety of problems. These can include:
- Dull, lack lustre skin with scales that are often pitted and dirty in appearance.
- Snakes often spend days soaking in their water bowls to reduce the irritation caused by the mites and to try and rid themselves of the parasites. The water left in the bowls often contains many dead mites. Unfortunately the spilt water along with the high temperatures in reptile enclosures creates a level of humidity that is ideal for mites to breed.
- Affected animals will often appear hyperactive or restless. They will often rub themselves against the cage furniture in an effort to scratch and remove the mites.
- Dysecdysis (a failure to shed normally) or an increased rate of shedding is also seen in affected snakes but not commonly in lizards.
Attention should also be paid to the enclosure. The inner surface of the lid, particularly the upper corners, and any hide boxes should be examined regularly for mites eggs, resting mites and mite faeces.
Principles of Reptile Mite Treatment
Once an infestation of reptile mites is identified it is possible for them to be eliminated, although this is not always easy. A few principles need to be understood and followed:
- Infestation is commonly associated with unsanitary cage conditions, poor husbandry practices (e.g. inadequate ventilation, damp conditions) and recent imports of new reptiles. Dark, moist and rough surfaces that are dirty are perfect places for mites to survive. It is therefore essential that these husbandry issues be resolved and cages be kept as clean as possible in order to achieve the goal of eradicating the mites. Unfortunately clean and well maintained enclosures can still suffer mite infestations.
- Some life stages of the reptile mite are very difficult to see, so if in doubt assume mites are present and treat for them.
- Adult mites and the nymphal stages can live up to 40 days off the host animal. It is therefore necessary for treatments to be repeated in order to prevent reinfestation.
- There is minimal scientific data available on the safety and effectiveness of the commonly used methods of treating reptile mites. There is likely to be significant species variation and so what appears to be effective and safe in one species may be ineffective or toxic in another. No treatment can be guaranteed to be 100% safe or 100% effective.
- Reptiles that are affected by mites may be unwell and may not cope with the treatment. For this reason it is recommended that all animals affected by mites be examined by a veterinarian familiar with reptiles in order to ensure they are well enough to be treated and that there are not any other underlying disease and husbandry problems. Animals that are sick may require fluids, antibiotics and other medications to stabilise them prior to mite treatment.
- For mites to be eliminated both the animal and its environment MUST be treated.
Reptile Mite Treatments
There have been a surprisingly large number of different treatments used with varying success and with varying side effects. The reality is that there is no one best method of controlling mites in every situation. The choice of treatment if often dependent on a number of factors including:
- The number of infested animals.
- The physical condition and age of the animal(s). Neonates, juveniles and small colubrid snakes, as well as any sick animals should be treated with care, particularly when using chemicals to kill the mites. In most cases it is preferable to avoid such chemicals and use a milder approach.
- The species being treated.
- The experience and budget of the owner.
- Water baths. Leaving the animal in a warm water bath for approximately 30 minutes will be sufficient to remove, but not kill, many mites. The technique is probably the safest with regard to being the least dangerous to the reptile and therefore is good for patients that may not cope with chemical control. It is not 100% effective as it does not kill the mites that have accumulated around the reptiles head. Never leave a soaking reptile unattended in its bath!
- Soap and water baths. Mites breathe through small holes called spiracles along the side of their bodies. When submerged mites are normally trapped in a thin bubble of air. The surface tension on the surface of the bubble prevents the bubble collapsing and allows the mite to avoid drowning. The addition of soap (e.g. dishwashing liquid) to the water disrupts the surface tension and results in the mites drowning.
- Oils. Cooking oils such as olive, vegetable and canola oils, cooking sprays and baby oil can be applied in a thin film over the animals body. This essentially smothers the mites. The treated animal should be housed on newspaper overnight, soaked in water the next morning to remove any dead mites and wiped dry. The process is then repeated until no more dead mites appear in the water after soaking. Like warm water baths cooking oil application does not kill mites in the environment but is safe for sick patients. This method can be messy so the wearing of old clothes is advised and be prepared for a slippery patient! Excess oil should be removed but is not harmful to the animal. It is not uncommon for the snake to shed individual scales after the treatment. This does not appear to harm the snake and the skin returns to normal after the next shed.
- Organophosphates. Organophosphates are a group of HIGHLY TOXIC chemicals that have been used in treating reptile mites. Examples include Trichlorphon (the active ingredient in the horse wormer, Neguvon) and Dichlorvos (the active ingredient in many brands of pest strips such as Vapona). A common practice was to place sections of dog and cat flea collars or placing pest strips in or on top of the reptiles enclosure for varying lengths of time. In some cases this results in the acute development of signs of toxicity (salivation, inability to right itself, muscle tremors, coma and death). More commonly though the prolonged contact with the poison results in a slow deterioration and ultimate death of the reptile. This may take months to occur. Prolonged usage is also likely to result in mites becoming resistant to the chemicals. Organophosphates are not only toxic to reptiles but to people as well. There is also evidence that dichlorvos is carcinogenic. Their usage is therefore STRONGLY discouraged.
- Pyrethrins/Pyrethroids. Pyrethrins are a natural chemical derived from the Chrysanthemum flower. Pyrethroids are a synthetic pyrethrin and have several advantages over the natural form. They have a rapid kill action, are less expensive, do not need additional chemicals to make them more effective, kill most insects and arthropods, have low mammalian toxicities (no studies have been done in reptiles), degrade readily to nontoxic compounds and do not accumulate in the environment. These groups of chemicals come in a variety of forms such as animal use liquid concentrates (e.g. Fidos Flea Rinse, Permoxin), aerosol sprays (e.g. Top of Descent Reptile Enclosure Insecticide), pump sprays (e.g. Aristopet Reptiguard) and human head lice treatments (e.g. Orange Medic Plus). The proper use of these chemicals is effective in killing mites on the animals and in the environment but toxicity has been reported, particularly when used incorrectly. Orange Medic was a very popular treatment until it was upgraded to Orange Medic Plus. The formulation was changed and there have been a few deaths reported with the new product. It is no longer recommended. Top Of Descent is an aerosol spray of a synthetic pyrethrin called d-phenothrin. It was originally developed for use in the cabins of aircraft but recently has begun to be formally marketed for use against reptile mites. It is biodegradable and is not stored in the body tissues. Its fine mist penetrates into where mites live. The product has also recently been scientifically evaluated by the Centre of Plant and Food Science at the University of Western Sydney. It is registered with the Australian Pesticides and Veterinary Medicines Authority and is now the most popular method of mite treatment and control. While this product is very good toxicities have been reported.
- Ivermectin. Ivermectin is a paraciticide used in cattle, horse and sheep to control gastrointestinal worms. It has been used as an injection (fortnightly for 2 to 3 treatments but they are painful) and as a spray once diluted. There are reports that Ivermectin has been fatal in young snakes and reptiles with lungworm infestation. Ivermectin is HIGHLY toxic to turtles and should NEVER be used to treat them.
- Revolution. This product is a spot-on flea and heartworm control for dogs and cats. Chemically it is similar to Ivermectin but has not been widely used and shows no greater benefit over other products.
- Insect Growth Regulators. Sprays containing insect growth regulators such a Methoprene have been tried on mite-infected lizards and snakes. These sprays also contain pyrethrins as active ingredients and cases of toxicity have been reported. Their use is not recommended.
- Desiccants. Silica gel powders have been tried as a treatment. They act by drying out the mites. They are very effective in doing this but unfortunately they are also very effective in drying out small snakes and lizards! The powder can also be inhaled by the reptile and its owner. The use of desiccants is not recommended.
- Frontline. Fipronil is the active ingredient in the dog and cat flea prevention product, Frontline. It is only available from veterinarians and comes as a pump spray pack or spot on treatments. It is usually applied by wiping the animal down with a cloth dampened with Frontline spray. Young, sick and certain sensitive species (namely boas) may be poisoned after treatment with Frontline Spray as the fumes are quite strong due to the alcohol carrier used and can cause damage to the respiratory tract. Ingestion of water contaminated with Frontline has also been reported to be toxic too.
- Freezing. This can be a method of ensuring cage furniture is free from mite. Placing them in the freezer for at least 5 days will kill snake mites.
- Microwaving. Like freezing using a microwave can be used to kill reptile mites on cage items. Just remember not to put any metal objects in your microwave oven!
- Baking. Heating objects to over 200C for 2-3 hours will also kill reptile mites. Objects in the oven should be check to ensure they are not being burnt though.
- Boiling. Boiling items for 20 to 30 minutes will kill reptile mites.
- Predatory mites. Certain species of Hypoaspis mites can be purchased to be released into reptile enclosures. This tiny light-brown mite naturally inhabits the top 0.5cm layer of soil. The female Hypoaspis mites lay their eggs in soil, which hatch in 1-2 days, and the nymphs and adults feed on the snake mites. Each Hypoaspis mite will consume 5-20 prey mites or eggs per day and their entire life cycle is 7-11 days. Some researchers worry that these mites could transmit diseases between enclosures and also that they can take some time to eliminate the reptile mites themselves. They may be useful though in facilities that house spiders, scorpions and insects that chemical sprays would otherwise kill. Mites can be purchased from www.biologicalservices.com.au
- Listerine baths. There are reports of people bathing their affected snakes in a bath with the mouthwash, Listerine. This has resulted in variable degrees of success and several deaths. It is not a recommended treatment method.
- Other products. There are a number of other products such as ZooMeds Mite Off spray becoming available. It contains coconut oil and other non-toxic ingredients. While these products may have some effect they are not as effective as other products that are available.
As a veterinarian who sees a large number of reptiles one of the most common questions I get asked is how I treat a reptile mite infestation. After making sure that the basic husbandry, hygiene and health of the animal is adequate I also explain the following disclaimer:
Most medications have not been formally registered for use in reptiles and dose rates are generally formulated using sound scientific principles from our knowledge of other species, or are generally accepted as a result of the experience of experts in reptile medicine. While all due care is taken to ensure the appropriate recommendations are made concerning medications, where medications are used off-label the client accepts all risk of adverse reactions and there is no liability on the manufacturer, the author, or the seller of the product.
I then use the following protocol.
Treating the Enclosure
- Remove the reptile(s) from the enclosure.
- Strip the enclosure of all furniture (i.e. bowls, rocks, branches, hides, plants, substrate etc.). Anything that can be discarded should be.
- The enclosure should be thoroughly cleaned and scrubbed with hot, soapy water, concentrating on cracks and inaccessible areas. This should be followed by a good quality disinfectant such as F10. Bleach can be used as an alternative at a concentration of 1ml bleach to 30mls water but all bleach residue must be removed and the enclosure well aired before putting the reptile back into it. Allow the enclosure to dry, preferably in direct sunlight.
- Once dry the enclosure and the surrounding areas should be thoroughly vacuumed, especially in the angles of the walls. The angles of wooden or melamine enclosures can be lightly scraped with a blunt knife to try and dislodge any loose eggs, mites and mite faeces. The enclosure should be vacuumed again. Discard the vacuum cleaner bag after use.
- Spray the Top of Descent in and around the enclosure, ensuring all surfaces are covered. Aim the spray into the fittings, cracks and poorly sealed sections where mites are likely to be hidden. A 2 x 3 x 2 enclosure usually requires a 3 to 5 second burst of spray. Top of Descent can also be sprayed around the outside of the enclosure. Do not place the animal(s) back in the enclosure for at least 15 minutes after spraying but ideally leave it empty for 60-80 days. Do not rinse out the cage after applying the Top Of Descent. After 24 hours return the water bowl to the enclosure.
- If not already done, seal the angles of the timber or melamine enclosures with silicone to remove any crevices where mites may live. Allow the silicone to set before placing the reptile(s) back into the enclosure.
Treating the Animal
- If treating lizards place a drop of artificial tears (available from veterinarians and chemists) in each eye as protection against absorption. Snakes do not require this as they have a protective scale over their eye.
- I use the water soluble Equimec (Ivermectin 10mg/ml). Dissolve 0.5ml in 1 litre water. Other types of Ivermectin can be used but may need to be dissolved in propylene glycol at a ratio of 1:2 to improve the water solubility. Concentrations and volumes will need to be adjusted to achieve a 5mg/L solution.
- Spray the animals body all over with the Ivermectin solution. Concentrate on the eyelids, corners of the mouth and other body crevices. Wipe the head with a cloth soaked in the solution or use a light spray. Keep the animals nose pointing towards the ground with the mouth closed to avoid any of the solution getting into the mouth or nostrils.
- Allow the medication to stay on the animal for 60 minutes and then wash the animal thoroughly in warm water. Place the animal in a very well ventilated mite-free enclosure with newspaper as the substrate.
- Repeat again 14 days and 28 days later (i.e. 3 treatments each 2 weeks apart).
- Any animals sensitive to chemicals such as geckoes, frogs, spiders and scorpions should be kept well away from the area being sprayed. Food insects such as crickets, cockroaches and mealworms should also be kept away.
- Wear protective clothing such as gloves and eye wear. Contact with skin should be avoided and if occurs the area should be thoroughly washed with soap and water.
- Ensure the area is well ventilated.
Mites will be transmitted on equipment, furnishings and clothes. It is therefore important to thoroughly clean everything between animals and enclosures. Any newly acquired reptiles should be quarantined for 3 to 4 months. They can be treated with the Ivermectin solution. The quarantine tank should be free of easily cleaned and free of cracks and crevices. Cage furniture should be reduced to cardboard boxes and newspaper. The tank can have a line of Vaseline placed around the rim to prevent mites escaping. Alternatively the tank can be placed in a shallow tray of water to create a moat that the mites cannot cross.