The present study aimed at identifying a mite infesting a colony of Aedes aegypti and Ae. albopictus as well as investigating the source of infestation. The mite species was identified after it was mounted on slides in Hoyer's medium and examined under an optical microscope. It showed to be Tyrophagus putrescentiae. Fish and rabbit food samples were kept in an environmental chamber at 27 degrees C and 90% humidity for 21 days and were weekly examined. The presence of T. putrescentiae was only observed in rabbit food. It is assumed that T. putrescentiae had been introduced into the colonies through phoresy among guinea pigs, which were kept at the time near the insectary under favorable conditions for their development (28.7 degrees C, 72% humidity, photoperiod of 14L:10D hours).