Lethbridge Herald, The (Newspaper) - February 5, 1974, Lethbridge, Alberta
MI UTHMIMI Research Station report Warble grubs an all-round pest By JERRY WEINTRAUB Entomologist Warble flies and their grubs are pests that affect different aspects of the beef industry at various times of the year. In winter and early spring, the grubs cut through the hides of cattle to make breathing holes under which they will grow within subcutaneous cysts, or warbles. In the interval since the previous spring, when the inch-long grubs first entered their host, they have travelled through the animal's body, growing slowly at the same time. In January, the growth accelerates and, by late February, each grub will be about one inch long and half an inch thick. In the spring, the mature grub drops from the animal, pupates on the ground, and produces a large fly resembling a bumblebee. These warble flies, which are often called heel flies, mate, though not necessarily near cattle, and the females lay their eggs on the hairs of cattle. Even though the egg-laying is painless, the flies cause the cattle to panic and run. The eggs hatch in about a week, crawl down the hairs, and burrow into the animal to restart the life cycle. Surveys have documen- ted the major costs attributable to war- ble grubs in packing houses. They include loss of meat spoiled by the grubs and the time taken hi trimming, degrading of carcasses, and spoilage of bides by the grubs' breathing holes. Losses to the feedlot operator and the cow-calf producer have not been emphasized enough, but re- cent experiments at the Lethbridge Research Sta- tion and elsewhere have shown some surprising effects. Wai tie grub activity does not reduce rate of weight gain equally in all classes of cattle. In the feedlot, for example, fast- finishing cattle suffer most, with grub-free cattle of this class gaining as much as 0.7 of a pound per day more than those that are grub-infested. Rates of weight gain of grubby and grub-free cattle of the slow-finishing class do not differ. In over- wintering weanling calves, weight gains are reduced in proportion to the number of grubs the animals carry. Losses are also caused by the frenzied running about of cattle trying to es- cape the adult flies during egg-laying. Such losses in- clude running-off weight, reduced milk flow, trampl- ed water holes and pastures, and damage from wire cuts and braises. While it is difficult to present definite values for damage at the feedlot ar.d the ranch, there is little doubt that grubs cause significant losses in all areas of the beef industry. DAVIS ENTERPRISES (ALBERTA) Pay the HlghMl PrteM for HIDES-SCRAP METAL-CAST IRON-BATTERIES ETC. ALBERTA STEEL PRODUCTS Dlvfeton of Davit InduMM Ltd. In Ntw Structural StMl, Angto, and Both Located at Phono 327-4035 or 327-6261 NATIONAL HOMES LIMITED There ore over 50 points of difference fond superiority] in a NATIONAL Home compared to others in the industry. YOU TOO, SHOULD MAKE A FEATURE-BY-FEATURE COMPARISON Before you tniy or build_ any home, make the comparison like we did you'll see over 50 points of difference in the National one.... BIGGER. BETTER. HEAVIER. THICKER. Compare such features as wall and roof sheathing, basic designing, cabinetry, windows and other important items more than enough to convince you of National's VALUE. See the complete range of over seventy component-built home designs in National's catalogues. Custom building too, if you have a favourite "dream home" plan. But before you start that all-important purchase, make the comparison of a NATIONAL home with any on the market Now how many homes can invite comparison like that? Send for information today. YES--- MORTGAGE FUNDS ARE AVAILABLE ACREAGE RURAL LOCAL AREA SALES AND SERVICE W. (Bill) Timms Calgary 246-3862 MAIL COUPON TODAY NATIONAL HOMES LIMITED BOX 245, ABBOTTSFORD, B.C. V2S 4N9 Please send me information about the home packages in National's catalogues. No charge or obligation. LH NAME ADDRESS .PHONE.