Poultry farmers and smallholders are seeing a massive increase in red mite populations this summer. Richard Turner from St David’s Poultry Team explains how to tackle them.
In the past few weeks we’ve encountered a 50% rise in the number of calls regarding red mite infestations, triggered by the warmer weather. Not only can red mites affect laying hens’ production, they pose a disease risk, and are a considerable irritant to both birds and humans. They can also cause the birds to become anaemic and even death.
Unfortunately, the life cycle of red mite (Dermanyssus gallinae) speeds up in warm, damp conditions, which is why we’re seeing particular problems right now. However, the blood sucking ectoparasites only emerge at night, so often the first signs of infestation are anaemic birds or blood-spotted eggs. It’s therefore vital that producers monitor for red mite colonies at least once a week for early warning signs.
The life cycle of red mites from egg to adult can be as fast as seven to 10 days so it’s important to keep checking your sheds, as populations can quickly become out of control, causing production knocks and stress to the birds. Mites hatch and go through two stages of being nymphs before they are mature to breed and lay their own eggs, so mite colonies can appear to double in size over a short time frame.
Mites that have not fed appear transparent; when they have fed they are red, and when digesting the blood they are black in colour. A good way to spot the mites is to check under the hens’ wings and around their vent area. Infestations are most common around perch ends, in nest boxes and in cracks and crevices, so look for grey ‘dust’ (mite excreta) in those areas. Other signs include loss of condition and production, restless birds, pale combs and wattles due to anaemia, and blood spots on eggs.
As the mites are most active after dark, it’s worth checking the shed at night with a torch, or wipe a piece of white paper around perches and cracks and check it for blood stains.
Of course, the best course of action is prevention, so houses should be treated with mite powder (diatomaceous earth) or insecticide between flocks. Diatomaceous earth is a natural product that is abrasive, cutting into the mites’ exoskeleton, dehydrating and killing them. Producers should check with their vet before applying any product while the birds are in lay, as there may be an egg withdrawal period.
Red mites are very resilient creatures and will not be killed with disinfectants, so having a cleanout policy using effective products to reduce their numbers when the birds are gone is imperative. Some treatments kill the mite and the egg; others only kill the adult mite, so insecticides may need to be repeated.
However, there is a serious problem with resistance to insecticides, so producers must ensure they use an appropriate product at the correct dose, and applied according to the instructions. They should also rotate active ingredients to avoid resistance building up.
Chickens that have suffered with red mite will need something to aid their recovery, especially if they have become anaemic. Producers can add specialist multi-vitamins to the drinking water that will energise the depressed hen. Stressed hens are always more susceptible to disease, which can be carried by mites between flocks, so it’s critical that producers act quickly to prevent a population explosion during this warmer weather.