Abstract
The effect of ambient temperature on the ability of Moniliformis dubius to become established in the intermediate host Periplaneta americana, and the effect of temperature on the rate of development of the parasite, has been investigated. Development is postponed at temperatures below 20 °C and infection does not normally occur at 37 °C, the parasites possibly being unable to avoid the defence mechanisms of the host. Both temperatures are tolerated by the host. A marked temperature dependence of rate of development is observed.