Biology
Stages of Development
Description of life stages
The basic mite life cycle includes an egg, a six-legged larva, one to three nymphal stages, and an adult stage (Spieksma 1990).
The life cycle of storage mites (Fig. 1) takes about 3 weeks at 25oC if the relative humidity is greater than about 80%. If humidity is below 65-70% the mites desiccate. Stages of development are egg, larva (6-legged), various nymphal stages (8-legged) and adult.
Infested foods smell sickly sweet or minty due to lipoid secretions of the mites and they also have a taste which renders the foods unsuitable for human consumption. A brownish mite dust can also be seen.
There is no specialised mode of egg laying or choice of oviposition site. The female extrudes eggs by expansion and contraction of the muscular walls of the large oviduct, the extruded eggs being pushed behind the body and left. The newly laid egg has a sticky, translucent coating which causes it to adhere readily to other eggs or mites or to any smooth surface (Cunnington, 1985).
Detail on lifecycle
Females retain the spermatophores acquired from the males. Each mating yields one spermatophore and females can mate between 16 and 40 times. Under optimum conditions, each spermatophore produces an average of 78 eggs over 23 days. Egg production varies widely on different foodstuffs and is highest on foods rich in carbohydrates and proteins (Cunnington, 1985).
Egg laying begins soon after eclosion and continues until death (Mason 2004, Chmielewski 2000).
Under optimum conditions, a female flour mite may lay 250 eggs per month in a lifespan of 40-100 days (Bennett 2003, Mason 2004).
Dispersal
A. siro is commonly found in birds nests in the shelter provided by houses and buildings, so birds are likely to aid in their dispersal (Solomon 1962).