Flour Mite
Mites and ticks belong in the phylum Chelicerata, class
Arachnida, order Acarina.
This is the commonest species (see
above) of mite in foodstuffs; it has reddish/pinkish legs.
Flour mites can live in almost any type of flour or in fodder
and, not least important, in stores of seed or corn. They
are also to be found on old cheese. A single female can lay
up to 500-800 eggs in her lifetime at a rate of 20-30 a day.
After hatching the life cycle consists of a larval stage, two
so-called nymphal stages and the adult stage, which at 25°C
is reached in three weeks. These mites can go through their
life cycle at a temperature as low as 0-4°C, but they do require
adequate humidity, and will not thrive if the relative humidity
is less than 65% as they will desiccate. The entire life cycle
may take only nine to eleven days to complete under the optimal
conditions of 90% humidity and 77° F. The life cycle is completed
in seventeen days at 64-71°F, and twenty-eight days at 50-60°
F. Flour mites are able to withstand periods where the conditions
are unfavourable. After the second nymphal stage they may pass
into what is known as hypopus stage which is a diapause form,
in which they are almost immobile and very resistant to desiccation.
In the hypopus stage, the body wall hardens and suckers appear
on the underside. These suckers allow the mite to attach to
insects and other animals for dispersal. The eggs and especially
the hypopuses appear to be more tolerant of insecticides than
other juveniles or adults; and they may be the primary stage
responsible for resurgences in mite populations after chemical
control appeared to have been successful.
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