What are mites?

One of the oldest forms of micro monster inhabiting your house, the mite is among the most diverse and successful invertebrates on Earth

(Image source: Pixabay)

48,200 species have already been identified and scientists postulate that this figure is only five per cent of the total number of mites on Earth. They are strong (for their size), durable and – most importantly – highly adaptable to change, evolving quickly to exploit the different environments presented to them over millions of years. In fact they have proved so good at adapting to Earth’s changing environment that mites – or more accurately, their sub-class Acari – have lived on Earth since the early Devonian period (416-359 million years ago), inhabiting the warmest and coldest climates and a vast array of living creatures. This evolutionary adaptability has granted mites almost unparalleled diversity and now, with the advent of the electron microscope, their numbers and types are visible for the first time.

Take the common house dust mite (Dermatophagoides pteronyssinus) from the pyroglyphidae family. This variant of mite dwells in human residences – including, as probability suggests, your home – and feeds entirely on organic detritus such as flakes of shedded human skin, flourishing in the stable environment and on the perpetual food supply. The dust mite is tiny and unseen, with a size of roughly 420 micrometers in length and 320 micrometers in height, highly reproductive – a female mite will lay 60 to 100 eggs in the last five weeks of her life – and impervious to all temperatures between 0°C and 60°C.

In essence, the dust mite is perfectly suited for life on Earth now, with the numbers of humans and houses in suitable climates (count yourself immune then in you live in Antarctica) in abundance. The ancestor that the common dust mite once shared evolved to take advantage of the rise of mammals (especially those which emerged from the nomadic tribal groups to set up permanent residences) and did so extraordinarily quickly. For while modern humans have only been around for 125,000 years, the Acari sub-class, as aforementioned, has been around for over 400 million. 

Meet the mites

1. Cheese mite

Found: food

Cheese mites infest cheese and other foods, and are usually seen as pests, causing spoilage and asthma in people breathing contaminated air. Some cheeses however, such as Mimolette, are deliberately infected with certain mites to create the correct flavour.

2. Dust mite

Found: Everywhere

Millions of dust mites inhabit homes, feeding on shedded skin cells. They mainly live in furniture, and are usually harmless. However, their excrement and dead bodies may cause allergic reactions in susceptible people.

3. Meal mite

Found: Kitchen

The Meal species of mite is a common pest of granaries, mills and kitchens, feeding particularly on grains and cereals. It reproduces rapidly under good conditions, while under unfavourable conditions it forms a resting stage in which it can survive Dust mite for over two years.

This article was originally published in How It Works issue 11

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