(1) D. albipictus, known as the winter or moose tick, is a common parasite of moose, elk and deer in the forests of northern Saskatchewan. As in the outbreak described in this paper, it may attack and cause serious losses among the cattle and horses of settlers which are permitted to graze in the haunts frequented by its native hosts. Deaths among the moose are frequently attributed to the ravages of the tick.

(2) The eggs of D. albipictus are deposited in the ground by the engorged females, which continue to drop from the hosts throughout the winter until the beginning of May. The larvae emerge from the eggs during the late summer and probably remain dormant until such time as the period of drought passes and cooler weather arrives. Attachment to the host is achieved by the larvae in the autumn, and both the larval and nymphal moults are undertaken on one and the same host. During the summer months the hosts are free from its attacks.

(3) Infestation of cattle and horses may be prevented by their maintenance in fenced, tick-free pastures or in barns from the end of September until the beginning of May. Animals that have become infested may be treated with an arsenical dip. Dipping, however, cannot be safely accomplished after September in northern Saskatchewan because of the risk of severe chills that may be contracted by treated animals consequent on the low prevailing temperatures of the autumn months.

Tick-infested fields may be cleaned by being ploughed in the spring after all the ticks have dropped. The engorged females are buried, and even though the eggs may hatch, the larvae will find difficulty in reaching the surface in the autumn to attach themselves to a host.