OCR Text |
Show DAMAGE DONE BY HORSEFLIES. All flics are to be condemned, according ac-cording to a bulletin of the United States agricultural department. Tho latest fly to be classed as an offender offen-der against the human family is the horsefly, charged with transmitting tho disease known as anthrax, which is fatal not only to animals but to man. The bulletin says it has been proved in experiments that horseflies, as well as the stable fly, carry this disease. In particular observations in the plateau region of west Texas furnish fur-nish important evidence that the horsefly is responsible In some degree de-gree for the spread of this disease to healthy animals. This fact, it should be said, does not in any way lessen the necessity for the other measures of controlling anthrax, such as the burning of carcasses and preventive inoculation. In fact, large numbers of horseflies have been observed, feeding feed-ing on animals which had either just died or were about to die from anthrax. an-thrax. At this time the blood is known to bo filled with tb,e germs of. the disease. The worry caused by the flies bites frequently causes animals to cease feeding and to group themselves together to-gether for mutual protection. When the pest is more than usually abundant abund-ant nervous animals are sometimes driven frantic and injure themselves in various ways. Furthermore, the loss of blood due to the attacks of the fly may be very sorious. Scientists Sci-entists in tho department havo studiod cases in which it waB estimated esti-mated that in the course of a single day several hundreds of Hies gorged themselves -with blood from one ani-mal. ani-mal. In addition to the blood drunk by tho flies, much was lost by trickling trick-ling out of the wounds mado by tho insects. Most of the species of horseflies breed in swampy places. For this reason the -numbers of tho flies decrease de-crease with the cloaring up and cultivation culti-vation of marshy areas. This of course is a very slow measure of re-rjaf, re-rjaf, and investigators have found tbat the process may be hastened by placing a film of keroseno on tho sur-(.in sur-(.in nf nnnlq nf water. All adult flies that strike tho kerosene are destroyed. de-stroyed. This system of control is valuable chiefly in regions whero thero aro comparatively few pools of water or in wooded areas where certain cer-tain pools are observed to be especially espe-cially attractive to the flies. , The adult fly frequently deposits its eggs on tho leaves of water plants growing in pools or along streams, but in west Texas It has been found that the eggs are usually deposited on rocks sticking out of running water. When first deposited (he eggs are almost whito, but they soon turn' almost black, or, in other cases, an ashy gray. The minute larvae or maggots hatch in a few, days and drop off into the water or mud. When full grown they change Into the pupal or resting stage and a few weeks after emerge as adult flies. Most of the species of horseflies horse-flies require nearly a year to complete com-plete this life cycle, and so thero is usually but ono generation annually. |