By far the greatest number of fungi known to be associated with cockroaches belong to the Laboulbeniaceae, genus _Herpomyces_, the species of which are restricted to parasitizing cockroaches (Thaxter, 1908). Most species are hyaline, small and inconspicuous (Thaxter, 1931) and are usually, but not exclusively, found on the insects' antennae. Species of _Herpomyces_ are highly, but not completely, host specific (Richards and Smith, 1954). While attached to the host, these fungi appear like minute dark-colored, yellow, or white (e.g., _H. arietinus_) bristles or bushy hairs (pl. 27, A). [Illustration: FIG. 1.--Diagram illustrating the relationship between a mature plant of _Herpomyces stylopygae_ and the integument of _Blatta orientalis_. (Reproduced from Richards and Smith [1956], through the courtesy of Dr. A. G. Richards.)] Richards and Smith (1955, 1955a) have studied the life history of _Herpomyces stylopygae_ on the oriental cockroach. The plants grow only on living cockroaches, and the infection is disseminated by contact. The mature plants are found mostly on the antennae (pl. 27, B), either on setae or on hard or soft cuticle. Spores are ejected from perithecia singly or in groups of 2 to 4 spores, although groups as large as 12 spores have been found. The presence of single, paired, or multiple spore groups on the surface of the host was correlated with the presence of single, paired, or multiple plants on infected cockroaches. Development from spore to mature perithecia takes about two weeks. The plant obtains nutriment from the host by means of a tubular haustorium that extends through the cockroach's cuticle and expands into a large bulb in the underlying epidermal cells (fig. 1). Infections on nymphs are lost when the nymph moults, but infections on adults persist throughout life. However, nymphs which have lost the fungus upon moulting are readily reinfected. Collart's (1947) statement that nymphs are never infected with _Herpomyces_ is not true.