Observations on infestations of undipped cattle of British breeds with the cattle tick, Boophilus microplus (Canestrini).

Abstract

A small herd of cattle infested with the cattle tick, Boophilus microplus (Canestrini) was kept in a previously unstocked paddock for 11 months without treatment for tick infestation. Frequent examinations showed that widely differing numbers of ticks developed on the cattle. The "tick resistance" of one animal, which showed no adult ticks during the summer months, could only be accounted for by mortality of the larvae and nymphs on the animal, since as many larvae were seen on selected small areas of this animal as on some animals carrying many adult ticks. The animals grazed together and thus would encounter similar numbers of tick larvae. The degree of susceptibility to adult tick infestation showed negligible correlation with skin thickness measurements and was not related to coat length. Larvae reappeared on the cattle 6 weeks after the first stocking of the paddock in March. The animals became almost free of ticks for 2 weeks in August. Although larvae were most numerous in November-December, they gave rise to fewer adults than the earlier wave of larvae in September- October. Some of the cattle suffered from "tick-worry'' in October, but thereafter their condition improved without treatment.