Could the acarid mite Tyrophagus putrescentiae (Schrank) be used as an environmental thermometer?

A proof-of-concept for the reconstruction of historical temperatures from museum collections of a commonly-occurring saprophagous mite is recounted. Technological readiness level 3 (TRL3) and TRL4 stage-gates were passed for a multiplex bioassay of ambient temperature using re-purposed laboratory data of setal and body sizes of female Tyrophagus putrescentiae (Acaridae: Astigmata) individuals. Higher temperatures yielded smaller mites with shorter setae. Partial predictive utility of environmental temperature using a composite scale measure was found for mites field-collected in the UK (≡TRL5 validation of use). Tyrophagid size in the wild appears individually variable and confounded in the cooler seasons through possible local heating effects (perhaps by virtue of their presence in numbers). Mite shape may change seasonally. Geographically dispersed detailed data-logging of micro-temperatures in the field together with targeted collection and characterization of mites at the same locations and measures of their local density is needed in order to advance such biotechnology to any demonstration of effective use all year round (≡TRL6) and final use in museum research.