Short communication A puzzling domestic infestation of the storage mite Tyrophagus longior Anne S. Baker a, * , Marc C. Swan b a Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK b Nuffield Department of Surgery, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK article info Article history: Accepted 24 May 2013 Keywords: Tyrophagus longior Storage mite Domestic infestation Infestation origin United Kingdom abstract Most UK records of the storage mite Tyrophagus longior are from stored and growing agricultural crops. It has rarely been found in human residences. A case is reported of an unexplained recurrent domestic infestation in a semi-rural dwelling in Staffordshire, England. The mite source was eventually identified as a hoard of dog biscuits found under floorboards within the house. The biscuits were evidently accumulated by mice infesting the house some 10 years previously. The authors hypothesise the mites were brought into the residence from local arable farmland by mice and/or the family dog and its owner. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The storage mite Tyrophagus longior (Gervais) (Acari: Astigmata) is a cosmopolitan member of the family Acaridae. It is a common occupant of stored foods, and also occurs in a variety of outdoor habitats such as pasture, tidal debris, and the nests of bumblebees, mice and birds (Fan and Zhang, 2007). Regarded as predominantly a fungivore, it will also damage seeds and glasshouse plants by direct feeding, has been shown experimentally to feed on cereal germ and is a major pest of cheese (Ribrioux, 1970; Jeffrey, 1976; Wilkin, 1979; Chmieliewski, 1984; Buxton, 2007). Tyrophagus longior is of medical significance as it is an important contributor of allergens that cause ‘barn allergy’, an allergic respiratory disease resulting from the inhalation of barn dust (Cuthbert et al., 1979). Tyrophagus longior occurs throughout the UK, including in island localities (Jeffrey, 1984; Hyatt, 1993). Most records are from cereal crops in storage or cultivation (Griffiths, 1960; Jeffrey, 1976, 1984; Emmanuel and Evans, 1979). On the rare occasions it has been collected in houses in the UK, the infestation was localized and/or comprised a small number of mites. A survey of three Orkney farms, for example, found it was limited to bedstead dust in one farm- house, despite being abundant in farm buildings, hay balers and stored hay on all three farms (Jeffrey, 1984). Colloff (1987) found a single specimen in dust samples collected from 74 houses in Glasgow. This is in stark contrast to the many thousands of mites involved in the recurrent infestation of a house in Staffordshire, England, reported here. 2. Discovery of the infestation In November 2011, the owners of an Edwardian residence situ- ated in a semi-rural location in Staffordshire returned from several weeks of absence to find a collection of pale brown powder on the floor tiles of the entrance hall (Fig. 1). The powder was adjacent to a utility cupboard and additional accumulations were noted on the dado rail directly above the cupboard, approximately 1.25 m from the floor (Fig. 2). No obvious source could be determined and the material was simply vacuumed up and the surfaces washed. Within 48 h the powder had recurred in similar quantities in identical locations. Again no source was readily evident and the deposits were cleared as before. On appearing for a third time, a biological infestation was suspected and microscopical examination of a powder sample revealed it was composed of a huge number of T. longior . All life stages present could immediately be distinguished from Tyrophagus putrescentiae, a common occupant of both indoor and field habitats, by the shorter dorsal setae d1 (less than twice the length of d2 versus at least twice the length) (Fig. 3) and the curved supracoxal seta decorated with a few short spines (versus basally expanded with long spines) (Fig. 4). A key to species of Tyrophagus and additional morphological characters are given in Fan and Zhang (2007). The affected area, including the contents of the cupboard, was thoroughly cleaned and treated with a proprietary topical insecti- cide. Within a week the infestation had recurred and a search for an undisclosed food source was begun. The hallway floor tiles were set * Corresponding author. Tel.: þ44 (0)207 942 5656. E-mail addresses: A.Baker@nhm.ac.uk (A.S. Baker), marc.swan@nds.ox.ac.uk (M.C. Swan). Contents lists available at SciVerse ScienceDirect Journal of Stored Products Research journal homepage: www.elsevier.com/locate/jspr 0022-474X/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jspr.2013.05.004 Journal of Stored Products Research 54 (2013) 64e66