Snake/reptile mite Ophionyssus natricis
Snake mites are parasitic mites commonly found on snakes, but also occurring on captive lizards, turtles, crocodiles and other reptiles. Feeding causes the bodies of the mites to be engorged with blood and fluids from the reptile.
Clinical signs include anorexia, depression, frequent rubbing against cage furniture, increased sloughing, and prolonged soaking in the water bowl. Mites may be seen crawling on the skin of the snake. With heavy infections anaemia can occur.
The mites feed by puncturing through the snake skin which can provide a point of entry where diseases such as Aeromonas spp. and Inclusion Body Disease (IBD) can be transmitted. Snake mites have been shown to act as vectors for IBD.
There are five life stages for the snake mite: egg, larva, protonymph, deutonymph and adult. The intermediate stages (larva, protonymph and deutonymph) must moult at least once to develop into the next stage. The ideal conditions for the mite to fully develop into an adult are at temperatures between 24-29°C and a relative humidity of 70-90%. The life stages can usually be completed in 13-19 days. Unfavourable environmental conditions will slow or halt development and decrease survivorship of all stages of the mites. All mite stages are killed when exposed to temperatures above 41°C or below 2°C for several days. In terms of humidity, the mites will desiccate at levels below 20%. The mites will also drown if they are kept immersed in water.
After hatching, the young mites go through a larval stage, which takes one or two days. The larvae do not tend to move very far away from the eggs, despite having the ability to walk. They do not feed in the larval stage.
The larvae develop into the protonymph stage, which can last three days to two weeks. At this stage the protonymphs become attracted to the smell of snakes and require a blood meal to go into the next stage. The protonymphs tend to walk around the scale surfaces and head plates of the snake.
The deutonymph stage takes place after a blood meal, usually away from the snake. Again, no feeding occurs while in this stage. Deutonymphs can survive for up to 31 days without feeding. Final moulting takes about a day to complete before the deutonymph becomes an adult mite. Adult mites continue to feed on the host and usually live for up to 40 days.
Once adults, the mites suck blood to engorgement (which takes four to eight days) and then lay approximately 20 eggs. Adult females feed two to three times at one to two week intervals and can lay up to 60-80 eggs in a lifetime. The eggs (off white to tan colour) are rarely laid on the snake, but are usually laid in dark and humid areas. Eggs laid at 25°C will hatch in 2-3 days, provided there is at least 85% humidity.
Snake mites are controlled by Hypoaspis miles.