Armadillidium vulgare is a terrestrial isopod that defends itself by conglobation, or rolling into a ball. Conglobation was elicited by placing woodlice on a platform heated to 40°C, the lowest temperature that elicited a response yet did not harm the woodlice. Woodlice were examined to determine whether habituation to heat occurred. This was accomplished by testing whether conglobation would decrease after exposure to heat over a series of trials. Each control woodlouse was exposed (n = 50) to a heat stimulus. Two trials per woodlouse were conducted, with a 38 min interval between trials. Each experimental woodlouse (n = 50) was exposed to the heat stimulus over a series of 20 consecutive trials with a two min interval between each trial. The variable was presence or absence of repeated trials. Control woodlice showed no significant difference in the frequency of conglobation between the first and the last trial. However, conglobation significantly declined in successive trials of experimental woodlice, indicating that habituation occurred. Dishabituation was examined by presenting the heat stimulus in intervals ranging from four to twelve min, extending each successive interval by two min. Control woodlice continued to respond every time they were exposed to heat. When the interval was lengthened to twelve min, 96% of the experimental woodlice recovered the conglobation response. Experimental woodlice still conglobated significantly (p < 0.001) less than control woodlice after a 4 min interval, but there were no significant differences in any subsequent trials (p > 0.348). The ability to habituate to innocuous stimuli is adaptive in nature where stimulus filtering allows animals to respond to biologically relevant stimuli. The data show that woodlice are able to habituate to a stimulus and then dishabituate, thus demonstrating non associative learning in crustaceans.