Strobiloestrus sp. larvae in cattle

A number of calves and a two year-old heifer in the Middelburg District of the Transvaal were found to harbour Strobiloestrus sp. larvae in nodules along their sides. Each nodule contained a single larva and these larvae developed from the early second stage to the third stage during the 25 day period between the first and last visit to the district. A particular set of circumstances involving the presence of klipspringers, which are considered to be the normal hosts of Strobiloestrus clarkii, grazing practice, hair colour of the calves and tick control probably resulted in the cattle becoming infested. A pour-on formulation of an insecticide was highly effective against the larvae.