Useful Methods to Control Mites

The mites are a widespread group of very small creatures – related to ticks as well as spiders and scorpions – which exploit a wide range of habitats and living conditions. Around 45,000 different kinds are currently known to science – but it is thought that there may be as many as twenty times more still to be discovered. The majority are plant eating, soil-dwellers, some being significant agricultural pests, others are animal parasites, while a small number infest stored foods.

The most common types of mite to be encountered in the home environment are likely to be spider mites, house dust mites and flour mites, each requiring different methods of control.

Spider Mites

Spider mites are plant pests, the red spider mite, for example, being a serious nuisance to a wide range of houseplants as well as in the garden and greenhouse. This pest is relatively large for a mite, measuring up to around 1mm in length and lays its eggs on the underside of leaves.

Infested plants become mottled, especially on the top surface of their leaves and when mite numbers are high, the leaves will discolour, wither and be dropped. Affected plants can become so weakened by a heavy infestation that they may not survive.

Controlling this fast-breeding mite is difficult; some specially designed pesticides can be helpful, but some strains of mite have developed resistance to certain types of insecticides – so a little trial and error may be needed to find the right one. Non-insecticide products based on plant oils or with fatty acids as the active ingredient offer one solution to this problem. Alternatively, a form of biological control is available by mail order, which uses one of the spider mite’s natural enemies – a predatory mite by the name of Phytoseiulus persimilis – against the pest.

House Dust Mite

This mite is probably the most universally known member of its clan and has been widely implicated in causing allergic reactions, asthma, rhinitis, conjunctivitis and dermatitis. The house dust mite is around a quarter of a millimetre long, making it virtually invisible to the naked eye. As the name suggests, this creature eats house dust, but since approaching 90 per cent of the “dust” in our homes is actually discarded fragments of our own skin – we each shed around one gram a day – the mite is effectively clearing up flakes of us!

House mites occur just about everywhere living amid the dust itself, but they are especially associated with bedding since they need humidity to survive, which the bed’s human occupants provide for eight hours a night in breath and perspiration. Anything between 100,000 and 10 million mites may be living in a typical mattress. Those sensitive to the mites or their droppings – especially children – may show allergic reactions and it has been estimated that dust mites may be behind 50–80 per cent of cases of asthma, as well as being implicated in a variety of other respiratory and skin allergies.

With so numerous and widespread a creature, eradication is unrealistic, so control focuses on reducing both dust accumulation – since the mites and their droppings are blown around in it – and minimising the population, principally by good housekeeping. However, if house dust mite allergy is suspected, the essential first step is to have any allergies or other medical condition thoroughly checked out by your doctor and follow any suggested advice. Typical control measures include replacing the natural fibre bedding with synthetic materials, regularly washing bedclothes, removing carpets in favour of alternative floor coverings and vacuuming and covering the mattress. There are also some specific products, such as Protector Mite and DM1, which are available for dust mite control.

Flour Mites

Chiefly a pest of grain stores, animal feed and flour mills, flour mites occasionally find their way into homes. They will eat almost any type of flour and can sometimes be found on old cheese, but require relatively high humidity to survive. Once in place, an infestation can grow quickly since a single female lays 500 eggs or more over her lifetime at a rate of around 25 per day.

Infested food develops a sickly-sweet smell and the flavour becomes tainted and heavily affected material is unsafe to eat, so any contaminated foodstuffs must be discarded and ideally destroyed and any affected cupboards thoroughly cleaned. Once these immediate steps have been taken, only storing vulnerable types of food in dry, cool conditions offers a really effective long-term method to control these pests.

The small – sometimes microscopic – size of mites often means that they go about their business unnoticed, which is fine for the majority of them. However, the activities of some kinds can affect us very directly – either in the garden, home or kitchen – and then it may take a bit of effort before we finally overcome this near-invisible foe.