[8] For fuller information see Farmers' Bulletin 1057, from which the directions here given are mainly derived.

[9] The chemicals employed have no effect upon iron. They will, however, actively corrode zinc, tin, or solder; hence a soldered pail must be watched for leaks and is far inferior to a seamless pail, stamped from a single sheet of iron. A tinned pail is preferred to a galvanized one, but a plain iron seamless pail or an iron kettle should be obtained if possible.

[10] Best done by previously determining by measurement the depth of 5 gallons of water in the kettle. Set the kettle exactly level and mark the depth on a stick held vertically on the center of the bottom.

ANIMAL PARASITES OF CATTLE.

By B. H. RANSOM, Ph. D.,

_Chief of Zoological Division, Bureau of Animal Industry._

The animal parasites of cattle comprise more than a hundred different species, belonging to various groups of the animal kingdom. Fortunately not all these parasites occur in this country--many are uncommon, and many are comparatively harmless. Some forms, however, occur frequently, and some are of distinct importance to the American stockman on account of the damage for which they are responsible. It is these parasites particularly which will be referred to in the present article, and although some forms are discussed which are rare or apparently of little economic importance, most of the minor and unusual parasites and species not found in this country have been omitted from consideration.

FLIES.[11]

Of the various species of flies which infest cattle some are injurious on account of the annoyance, pain, and loss of blood due to their bites, and sometimes also on account of diseases or parasites which are thus transmitted from the blood of diseased animals to that of healthy cattle, while others, which in the winged adult state do not bite, are injurious because they live parasitic on cattle during their larval stages.

_Remedies for flies._[12]--Most remedies used for protecting cattle from the attacks of flies have to be applied frequently, and few, if any, will keep flies away for more than a day or two following their application. The numerous proprietary fly repellents to be found on the market are usually more expensive, and often less efficacious than homemade mixtures.

At the Minnesota experiment station rancid lard 1 pound and kerosene one-half pint, mixed thoroughly until a creamy ma.s.s forms, was found to give excellent results as a fly repellent, lasting for two or three days, when rubbed not too thickly with a cloth or with the bare hand over the backs of cows. Mixtures of cottonseed oil and pine tar containing from 10 to 50 per cent of the latter substance were found by investigations in the Bureau of Animal Industry to have a marked repellent action against flies when applied lightly every day. A too free application of tar mixtures and other preparations containing phenols is liable to cause poisoning; hence care should be observed in this regard.

Jensen (1909) recommends the following formula, which is said to protect cows for a week:

Common laundry soap 1 pound.

Water 4 gallons.

Crude petroleum 1 gallon.

Powdered naphthalin 4 ounces.

Cut the soap into thin shavings and dissolve in water by the aid of heat; dissolve the naphthalin in the crude oil, mix the two solutions, put them into an old dasher churn, and mix thoroughly for 15 minutes. The mixture should be applied once or twice a week with a brush. It must be stirred well before being used.

THE STABLE FLY (STOMOXYS CALCITRANS).[13]

This fly very closely resembles the house fly, but, unlike the latter, it is a biting fly. It is common about stables and often enters dwellings, especially in cloudy weather. According to Noe, it is the agent of transmission of a parasitic roundworm of cattle (_Setaria l.a.b.i.ato-papillosa_, see p. 529). This fly has been shown capable of transmitting anthrax from diseased to healthy animals, and under some conditions it may transmit surra, a disease caused by a blood parasite which affects horses, cattle, and other livestock.

The annoyance suffered by cattle and horses from stable flies is much lessened if the stables are darkened.

The screening of doors and windows, however, is preferable, as ventilation is not interfered with as it is in darkening stables. For milk cows coverings made from burlap (double thickness), including trouserlike coverings for the legs, may be used when the flies are very numerous and troublesome. One of the fly repellents mentioned above may be applied to cattle to protect them from stable flies. The Hodge flytrap fitted to the windows of dairy barns is a useful means of destroying stable flies. The United States Bureau of Entomology has found that a mixture of fish oil (1 gallon), oil of pine tar (2 ounces), oil of pennyroyal (2 ounces), and kerosene (1/2 pint) is fairly effective for a short time when applied lightly, but thoroughly, to the portions of animals not covered with blankets. The risk of poisoning with tar mixtures as already mentioned should be borne in mind in using this remedy. Care should be taken to apply it lightly.

The stable fly breeds in moist acc.u.mulations of straw, chaff, cow or horse manure, and various fermenting vegetable substances. The debris collecting in and under outdoor feed troughs, and the remains of straw stacks are favorable breeding places for the stable fly. Under the most favorable conditions about three weeks are required for development from the egg to the adult stage.

The proper care of straw and the proper disposal of stable manure are very necessary in the control of stable flies. Straw stacks should be carefully built so as to shed rain, and loose straw or chaff should be scattered or burned. Straw not required for winter feed should be promptly disposed of by burning or scattering and plowing it under. Stable manure should be hauled out and scattered at regular intervals, preferably every three days, and the vicinity of stables should be kept free from acc.u.mulations of straw and hay that may become wet and serve as breeding places for the stable fly.

THE HORNFLY (LYPEROSIA IRRITANS).[14]

This fly, now found nearly everywhere in the United States, was introduced into this country from Europe about the year 1885. Hornflies have the habit of cl.u.s.tering about the base of the horn (fig. 2), whence the name by which they are popularly known. They do not damage the horn, and congregate there only to rest.

In view of the general practice of dehorning cattle, the name hornfly is less distinctive than it once was. Moreover, hornflies rest on other parts of the body as well as the horns.

When resting, their wings are held down close to the body (fig. 1); when feeding, their wings are held out nearly at right angles, ready for flight.

They puncture the skin and suck blood, usually attacking the upper parts of the body, particularly those which are out of reach of the animal's head or tail. Unlike most flies, they remain on the animal more or less constantly, day and night. Owing probably to the irritation and annoyance caused by these flies, cattle often do not thrive as they should during seasons when the flies are numerous. The hornfly has also been charged with transmitting diseases, such as anthrax.

[Ill.u.s.tration: PLATE XLIV. NORMAL SPLEEN AND SPLEEN AFFECTED BY TEXAS FEVER.

Fig. 1. SPLEEN OF AN ACUTE, FATAL CASE OF TEXAS FEVER.

Fig. 2. SPLEEN OF HEALTHY STEER.]

[Ill.u.s.tration: PLATE XLV. TEXAS FEVER.]

[Ill.u.s.tration: PLATE XLVI. THE CATTLE TICK (MARGAROPUS ANNULATUS), THE CARRIER OF TEXAS FEVER.]

[Ill.u.s.tration: PLATE XLVII. THE CATTLE TICK (MARGAROPUS ANNULATUS).

Figs. 1 and 2 DORSAL AND VENTRAL VIEWS OF MALE.

Figs. 3 and 4 DORSAL AND VENTRAL VIEWS OF REPLETE FEMALE. (GREATLY ENLARGED.)]

[Ill.u.s.tration: PLATE XLVIII.

PORTION OF A STEER'S HIDE, SHOWING THE TEXAS-FEVER TICK (MARGAROPUS ANNULATUS) OF THE UNITED STATES. NATURAL SIZE. ORIGINAL.]

[Ill.u.s.tration: PLATE XLIX.

FIG. 1.--TICK-INFESTED STEER.]

FIG. 2.--DIPPING CATTLE TO KILL TICKS.]

[Ill.u.s.tration: PLATE L. FACSIMILE OF POSTER USED IN TICK ERADICATION WORK.]

The fly lays its eggs in freshly dropped cow manure. They hatch in about 24 hours, and the larvae or maggots in four or five days develop to the pupal stage, which lasts a week or 10 days. From the pupal stage the mature fly emerges. The entire process of development from the deposition of the egg to the appearance of the mature fly therefore may be completed in two weeks, or even in a shorter time. To protect cattle from attacks of the hornfly they may be treated with one of the remedies mentioned above (p.

502). Dipping cattle in a vat provided with splashboards set at the proper angle destroys most of the hornflies present on the animals. Unless the splashboards are used all but a few of the flies succeed in escaping as the cattle plunge into the bath and later return to them. Scattering the droppings of cattle with a shovel, or with brush dragged over pastures, in order to insure the rapid drying of the manure and consequent destruction of the larvae, is, when practicable, an efficient means of reducing the number of these flies.

[Ill.u.s.tration: FIG. 1.--Hornfly (_Lyperosia irritans_) in resting position. Enlarged. (From Bureau of Entomology.)]

[Ill.u.s.tration: FIG. 2.--Hornflies (_Lyperosia irritans_) on cow horn. (From Bureau of Entomology.)]

BUFFALO GNATS.

These small flies, also known as black flies, are about one-eighth of an inch long and have a characteristic "humped" back (fig. 3). They breed in running water and appear in swarms during spring and summer, often in enormous numbers, causing great annoyance to stock and human beings, on account of their bites and their entrance into the eyes, nose, mouth, and other openings of the body. Their bites appear to be poisonous, and in seasons especially favorable to the gnats heavy losses of horses and cattle often occur.

Buffalo gnats are more troublesome in bright, sunny weather than when it is cloudy, and animals which have not shed their winter coats suffer more from their attacks than those with smooth coats. Cattle kept in darkened stables are not molested. The application of one of the fly repellents already mentioned (p. 502) may help to protect animals from buffalo gnats. The burning of smudges is also a useful means of protecting stock from the attacks of these flies.

[Ill.u.s.tration: FIG. 3.--Buffalo gnat. Enlarged. (From Bureau of Entomology.)]

SCREW WORMS.[15]