The life history data of Neotrombidium species are reviewed, together with a detailed study of the bionomics of N. beeri. A technique was developed for rearing N. bee1•i in the laboratory. The larvae were allowed to engorge on their natural host, Alobates pennsylvanica (DeG.) (Coleoptera: Tenebrionidae). Nymphs and adults fed upon the eggs of Tenebrio molitor Lin. (Tenebrionidae). 243 eggs required an average of 32 days for larval emergence, at laboratory temperatures. A deutoval stage preceded the larva. A minimum of about 14 days of feeding was required before the larvae could continue development to the nymph. 31 nymphs emerged from larvo-pupae after II to 20 days. Nymphs entered pupation after at least one engorgement on aT. molitor egg, 10 to 214 days after emergence from the larvo-pupa. The nympho-pupa required from II to 21 days before adult emergence. Twenty-one adults, 12 females and 9 males, were obtained, living up to 3 years after eclosion from the egg. One of these laboratory-reared females supplied 243 eggs, from which an Fr generation of adults was reared. Neotrombidium beeri shows a degree of host specificity towards tenebrionid beetles. Larval mites were commonly collected from under the elytra of Alobates pennsylvanica, and laboratory-reared larvae placed upon this host readily engorged and completed development The larvae were placed upon several other potential beetle-host species, but were unable to complete development. The post-larval instars refused a large assortment of nutrient material, but readily accepted T. molitor eggs.