Dispersal of the larvae of the cattle tick Boophilus microplus (Can.) was studied in connection with problems of controlling and eradicating this pest and bovine babesiosis in New South Wales. Larval ticks were recovered by pressing flannelette-covered boards on to the pasture or litter surface, or sampling with cattle. Many of these larvae were capable of completing parasitic development.

Strong winds were an important factor in determining the distance travelled, as the longest journeys in pasture were for the most part in the directions in which the larvae would have been carried by recorded strong winds. Much of the dispersal is accomplished when larvae are transferred from one grass blade to another moving in the wind, but a great number of airborne larvae were captured on tanglefoot-covered traps. Movement by wind was clearly demonstrated over short pasture, up to 100 ft and possibly as far as 260 ft from the point of hatching. In long grass one larva travelled 83 ft, but in scrub and forest the greatest distance travelled was 15 ft. Many larvae that travelled long distances were capable of completing development on cattle.

Tick larvae could be transported by casual hosts and then dropped in a viable condition. A horse carried larvae for 900 ft, a rat and cockerels 100 ft, a magpie in flight 600 ft, and a pigeon in flight half a mile. A horse dipped six days earlier in ethion dropped live and viable larvae after transporting them 150 ft.

Security has been improved against the movement of larvae from the Cattle Tick Research Station, Wollongbar, New South Wales, to neighbouring properties, and from Queensland into New South Wales, by widening existing buffer zones to 330 ft. Inspectoral staff are now required to spray themselves and their horses before re-entering New South Wales from the buffer zone.