After the eggs hatch, the larval ticks, which emerge from them, when they succeed in finding a host, enter the ears and gradually develop to the stage at which they are ready to leave the host animal. The females may live several months, or even years, if they do not find mates. After mating they may deposit their eggs intermittently. Hatching of the eggs may occur as early as 10 days after deposition. The larvæ may live for 80 days without a host. The parasitic period has been observed to vary from about two to about seven months.
Treatment.—On account of their habits and great vitality and their occurrence in various kinds of animals besides cattle, complete eradication is a difficult problem. The only effective treatment known is to introduce directly into the ear passages a remedy that will kill the ticks. Later, of course, the cattle may become reinfested from exposure to infested ranges or inclosures. The following mixture, however, in addition to killing the ticks in the ears, will protect against reinfestation for about 30 days: Ordinary commercial pine tar, two parts; cottonseed oil, one part—in each case by volume. Animals to be treated are confined in a chute, and the mixture is injected into the ears with a syringe, after the wax and other débris in the ears have been cleaned out with a wire probe that has an eyelet at one end. Further information concerning ear ticks and the details of their treatment is given in Farmers' Bulletin 980.
BLOODSUCKERS OR LEECHES.
Fig. 12.—Portion of the wall of the first stomach with conical flukes attached.
These worms are sometimes taken up by cattle when drinking from ponds. They may attach themselves to the inner surface of the mouth or nose, and sometimes reach the upper part of the windpipe or of the gullet. Bleeding at the mouth or nose may be noticed, the membranes where the leech is attached are liable to be swollen and congested, and as a result of the loss of blood a condition of anemia may result.
Treatment.—If the worm can be reached it may be destroyed by cutting it in two with a pair of scissors, or it may be removed with forceps or with the fingers after wrapping a towel around the hand so that the worm can be held without slipping. Fumigation with tobacco or tar may cause the worm to release its hold if it can not be removed by other means. Ponds may be rid of infestation with bloodsuckers by the introduction of eels.