Some Insect Pests of Horses and Mules

Some Insect Pests of Horses and Mules BY F. C. BISHOPP ^ HERE IS condensed and practical information about several enemies of the horse and mule, including mosquitoes^ sand flies (punkies), houseflies, horseflies, deer flies, buffalo gnats (blackflies), fleas, lice, and ticks. Special attention is given to control measures. A CONSIDERABLE KUMiiER of iiisccts and inscct relatives attack equines in addition to the horse bots, stableflies, ticks^ screwworms, and mange mites discussed in other articles in this book. Some of them, such as the biting and sucking lice of horses and mules, are specific; some, like the tropical horse tick, attack other animals but prefer to feed on equines; and many others feed on various warm-blooded animals with- out seeming to prefer any one kind. A number of such pests at times become so abundant locally as to have serious effects on horses, causing poor condition, lower work output, difliculty in handling, and even death. MOSQUITOES AND SAND FLIES Many kinds of mosquitoes and sand flies, or punkies, attack horses and nmles. As a rule, a moderate number of these insects do not greatly annoy horses; but the presence of large numbers sometimes constitutes a serious problem, especially amon^ high-strung animals such as race horses. Difficulties due to these insects have been en- countered at meets and fairs held during the late spring and early fall in cities along the south Atlantic coast. Screening the stables gives some protection against mosquitoes. Sand flies, however, readily pass through ordinary screens, and smudges and sprays are resorted to for relief from them. Painting the screens in the evening with a mixture of 1 part pyrethrnm extract 1 F. C. Bishopp i« Assistant Chief, Bureau of Entomology and Plant Quarantine. .492 Some Insect Pests of Horses and Mules 493 concentrate and 20 parts lubricating oil (S. A. E. 5), together with the use of a pyrethrum-kerosene spray in the buildings, is effective.^ Pasturing the horses on high ground free from dense woods and underbrush reduces the mosquito and sand fly hazards outdoors. Eliminating stagnant water in and near pastures, emptying and cleaning water troughs frequently, and, in salt marsh areas, ditch- ing the parts of the marsh known to produce mosquitoes are effective steps in preventing trouble. Since there are many species of mosquitoes and they have widely divergent habits, control measures must be modified to fit the situation. After stagnant water has been elimi- nated as far as practicable, the principal lines of attack are: (1) Apply No. 2 fuel oil lightly to the surface pools where mosquito wig- glers are found; (2) keep livestock on high, open pastures when mosquitoes are abundant; (3) keep valuable animals in screened barns; (4) use kerosene-pyrethrum sprays to kill the mosquitoes on animals and in the barns; and (5) make smudges in which stock may find' protection during severe mosquito outbreaks. In this brief account it is not possible to discuss all the different methods of controlling mosquitoes. The reader is therefore referred to other published articles that supply more details (i, 4? '^)-^ The fact should not be lost sight of that at least eight American species of mosquitoes have been shown to be capable of carrying equine encephalomyelitis. Epizootics, or severe outbreaks, of this disease are usually concurrent with mosquito outbreaks, and pro- tecting animals f nom mosquito attack appears to be of some value in preventing the disease. THE HOUSEFLY The housefly is not of great importance as an enemy of the horse, but, if not controlled, it breeds in tremendous numbers in horse manure. The presence of this insect in abundance is a serious hazard to human health. The housefly annoys horses by its persistent efforts to feed on body secretions, particularly those of the eyes. This leads to the suspicion that the flies may transmit certain infectious eye diseases. The housefly is an intermediate host and transmitter of the roundworm para- site of equines, Habronema muscae (8), and it has also been shown to be capable, of. transmitting mastitis of cattle. The control of houseflies depends on the proper disposal of manure and vegetable refuse (S). Scattering such materials thinly over fields soon to be plowed is the most satisfactory method of handling them. Manure may be stored in fly-tight manure pits or on racks over water. Treating manure with borax at the rate of 11 ounces to each 8 bushels also checks fly breeding. If the manure is to be used as a fertilizer, borax should not be used in excess of this amount. Care should be exercised not to apply too large an amount of treated manure to soil, since applications heavier than 15 tons per acre are likely to injure some crops on certain soil types. 2 UNITED STATES BUREAU OF ENTOMOLOGY AND PLANT QUAEANïINE. SAND FLIES AND PUNKiEs. U. S. Bur. Ent. and Plant Quar. Cîr. E-441, 3 pp. 1938. [Processed.] = Italic numbers in parentheses refer to Literature Cited, p. 499. 494 Yearbook of Agriculture, 1942 Tlic use of properly bnitod fly trii])s as well as of keroseiie- pyrethruin fly sprays is an important siipplomontal control measure. Instructions for makino; a tlioroujihly practical fly trap will be fonnd in Farmers" Bulletin 734. Flytraps and Their Operation. HORSEFLIES AND DEERFLIES The blood-sucking insects known as Iiorsetlics and deer flies are often very troublesome to horses. Their bites are painful, and when the insects are numerous, they draw considerable blood. They also act as carriers of anthrax, the Asiatic disease surra, and possibly other equine maladies. There are many kinds of horseflies and deer flies of various sizes and colors (fig. 1). Some are relatively small, not more than half an inch in length, while otiicrs are three times that size and very lobust. These pests are widely distributed in this coun- trj\ being found in greatest numbers in marshy or swampy areas and along streams, where they breed. The eggs are laid on plants FiCURE 1.- -A species of horselly. Three times iialiiral growing in or over the size. water or on stones in . streams. xVfter hatch- ing, the larvae drop into the water and buirow into the imid or gravel, wiiere they feed on small, soft-bodied animals. After nearly a year they pupate in the moist soil near the water, and soon the adult insects emerge. The adults are strong, fast fliers and may be found several miles away from water, but they are usually more abundant near it. As the breeding habits suggest, control is very difficult. Draining swamps and seepage areas along streams, deepening and straighten- ing the edges of lakes and ponds, and preventing accumulations of waste irrigation water in low places in meadows tend to reduce the mimber of horseflies. Wlien these pests are abundant, animals in harness may be given some relief by the use of burlap coverings. Darkened sheds and smudges ofl'er some protection to livestock not being worked. Horse- flies are not easily rei)elled, and as the individual flies usually remain on the animals for only very short periods, fly sprays are of little -value. BUFFALO GNATS Buffalo gnats, or blackflies, are pests of nearly all warm-blooded animals, but certain species prefer certain hosts. They are small, Some Insect Pests of Horses and Mules 495 rather heavy-set, humpbacked flies, or gnats (fig, 2). The bites they inflict on human beings are often very irritating; when there are many bites, the face and arms may become swollen, and severe generalized symptoms may result. Livestock are greatly annoyed by the bites of these insects. In severe outbreaks of the southern buffalo gnat in the lower Mississippi Valley many mules die, cattle nnd liorses are reduced in flesh, milk flow is cut, and the coats of the animals become rough and unsightly. Buffalo gnats breed only in running water. The larvae attach themselves to sticks, logs, stones, and aquatic plants in the faster flowing parts of streams. Stones or dams over w^iich water is rush- ing are often literally covered with the larvae, which, when fuU- o'rown, are from one-third to one-half inch in length. The larvae usually require several months to develop; then they pupate in cornucopialike structures which they spin on rocks in the water. The gnats burst out of the pupa skins and in some way reach the surface of the rough water and fly off. The adult females appear to require one or more meals of blood before eggs develop. These are laid in a gelatinous mass on stones or twigs at the water's surface or, as in the case of the southern buffalo gnat, are dropped singly on the water as the females di]) to the surface from the swarm of gnats dancing over it. Bradley (2) has found that the eggs of thé southern buffalo gnat sink to the bottom and do not hatch until the following FIGURE 2.—Adult buffalo s])ring when floods occur again. The eggs gnat, or blackfly. Much of most species hatch in a few days. enlarged. The southern buffalo gnat usually appears in swarms in the lower Mississippi Valley during the first warm period of late winter or early spring. If the floods are widespread and the weather continues warm, tremendous numbers of gnats emerge. After a few weeks the gnats disappear, sometimes very suddenly. The turkey gnat {EiisimuMmn méridionale)^ which usually appears later in the spring than does the southern buffalo gnat, attacks livestock to a limited extent but is especially destructive to poultry. Preventing the breeding of the southern buffalo gnat is very difficult.

Load more