Egg -- The minute egg is pearly white.
Larva -- The 6-legged larva is translucent and whitish.
Nymph -- Like the adult, the 8-legged nymph varies from grayish to deep red, depending upon its blood content.
Hosts -- Chickens are the primary hosts of poultry mites, but turkeys, pigeons, canaries, and wild birds, especially English sparrows, may also be hosts. In the absence of birds, man can be the host of northern fowl mites. Even house mice and Norway rats have been found to transmit northern fowl mites to poultry.
Damage -- The loss of blood (anemia) and irritation caused by mite infestations lead to decreased vigor and egg production of the host. Young birds and setting hens may actually be killed by mite-induced anemia. Moreover, poultry mites can harbor and transmit various viruses, including encephalitis.
Life History -- The major difference between these two North Carolina mites is their feeding time. Chicken mites are usually nocturnal; they hide in sheltered areas of the poultry house during the day and feed upon the host at night. Northern fowl mites are found on or nearby their hosts continuously, even during the day.
The life stages of both mites consist of the egg, larva, protonymph, dentonymph, and adult. With the chicken mite, 12 to 24 hours after its first blood meal fertilized females lay batches of three to seven eggs in crevices or under debris in poultry houses. During her lifetime of several months, she lays up to 32 eggs. Incubation lasts 48 to 72 hours. The larva, which does not feed, molts in 1 to 2 days to a protonymph, which takes a blood meal. In a few days, it molts to the dentonymph which does not feed. This stage molts to the adult stage after 1 or 2 days. Under optimal conditions, a life cycle (egg to egg-laying adult) req uires only 7 to 9 days. However, both feeding nymphs and adults may go several weeks without blood meals, thereby increasing the duration of the life cycle. Chicken mites usually hide in cracks during the day and feed only at night. Northern fowl mites usually spend the whole life cycle on the host although when large numbers of mites occur, the mites may team on nesting materials and eggs. Northern fowl mites can survive about 3 weeks in the absence of a host, whereas chicken mites may survive several months without feeding.