In spite of the clinical importance of the bite of the Latrodectus mactans no complete study of its life history has so far been made. In view of this fact and since it is the only spider found in this country the bite of which has definitely been proved capable of causing severe1 and, in some cases, fatal2 systemic reactions in man, observations on its life history are of interest. The observations presented are based on a two year study of this spider as found in the vicinity of Tuscaloosa, Ala. It includes observations of the spider both in its natural environment and as raised in captivity.
The full grown female Latrodectus mactans (fig. 1, G and H) has a large, globose abdomen attached by a slender pedicle to the much smaller cephalothorax. The body of an average-sized adult female is ½ inch (1.27 cm.) in length.