"The horn fly, Haematobia irritans (Linnaeus), was introduced into the United States about a century ago. Since then, it has become one of the most important fly pests of pasture and range cattle. Although most cattle can tolerate up to 200 horn flies without showing economic losses, larger numbers of these flies decrease cattle weight gain and milk output."--First page.Robert D. Hall and Kathy E. Doisy (Department of Entomology), C. Haskins Teasley (Department of Agricultural Engineering, College of Engineering)New 8/87/6

Doisy, Kathy E.

Hall, Robert D.

Teasley, Haskins C.

English

University of Missouri: MOspace

== In u II II II []A ~ (] ·;,= ~r, ~--: E ~I bid- @g&11r-L..~lf ~ ~ .\ r, ~ [j, ~ I: flJ ;ail:: ■ (r-reJ■ mJ-,i BBB- ;e:, ~ ifii· r_ I , ~ ==~ 117--_ ""1 E:i•=• =• =If_~ • ~""' - ~ ill- :.-17 ...J ~ .r, ~ ~~IIilf"! .c..~.m iiit1 I _,iii, @ .-... lv l 1r. nJL b, I .:.li.,_ ui:, n _,_ ,1-1 t. 11 iJ.• I I~. 181::U~· 11'1 :u, rll. •~r u •_ C ll II u ~ u u u I Walk-through trap to control horn flies on cattle Robert D. Hall and Kathy E. Doisy Department of Entomology C. Haskins Teasley Department of Agricultural Engineering College of Agriculture The horn fly, Haematobia irritans (Linnaeus), was introduced into the United States about a century ago. Since then, it has become one of the most important fly pests of pasture and range cattle. Although most cattle can tolerate up to 200 horn flies without showing economic losses, larger numbers of these flies decrease cattle weight gain and milk output. Male and female horn flies feed on blood by using a rigid mouthpart underneath their heads. This feed-ing activity is painful and annoys cattle. Horn flies congregate on the backs of cattle, often clustering on the midline and spreading down the sides. Some-times, horn flies settle around the bases of horns, and if the weather is extremely hot, they may move onto the belly. After the flies feed and mate, the female is ready to deposit eggs. She moves to the rear of the cattle host and flies to the ground as the animal defecates . This covers the female horn fly by dung. This activity occurs frequently during early morning. NOV 2 3 1987 • Horn fly eggs are small, reddish-brown and gen-erally laid in clumps on grass and other vegetation covered by the cow pat. After a time, which varies depending on temperature, the eggs hatch, and mag-gots develop in the dung. When mature, the maggots pupate in or below the pat, and later, emerging adults disperse to seek cattle hosts. As summer progresses, more horn fly eggs develop but only mature to the pupal stage. Rather than emerging as adults, they overwinter (diapause) . Diapausing pupae produce adult horn flies the following spring. Horn flies have been controlled with insecticides since the early 1950s. Sprays, rub-ons or pour-ons were effective, but many insecticides, such as DDT Figure 1. The trapping elements are in place, as viewed from the side. These elements are held into the framing with screw hooks and eyes and can be re-moved for maintenance. G1195 • II u Archive version- cck for updatesFigure 2. An interior view of the trap shows the screen placement in a trapping element. The screen is stapled to ¾ -inch by ¾ -inch wood strips that are nailed to the sides of each element. and toxaphene, are no longer permitted. Now, appli-cating devices, such as cable backrubbers (see UMC Guide G7012, "Making and using a cattle backrubber") and dust bags, are popular for horn fly control because they require little labor on the behalf of humans . When these systems are charged with effec-tive insecticide and properly situated, the cattle treat themselves. Insecticide-impregnated ear tags are also popular for controlling horn flies on cattle. These tags gen-erally employ pyrethroid insecticides and, until re-cently, gave almost complete control of horn flies for a summer season. Resistance to the pyrethroids de-veloped in southern horn flies, however, and spread northward. By 1986, resistance was reported as far north as the Canadian border. Cattle producers are dissatisfied with the performance of insecticidal ear tags and are requesting information about alternative control methods. Overview of the horn fly trap In the 1930s, U.S. Department of Agriculture ento-mologist William Bruce became interested in design-ing a walk-through trap for horn flies . He experiment-ed with several designs, perfected one and deposited schematic drawings and an explanation of his trap with the National Agricultural Library in Maryland . Soon after Bruce completed his experiments, however, the United States became involved in World War II, and few people were thinking about horn fly control. After the war's end, DDT and other pesti-cides captured the attention of the public and the entomological and agricultural communities . Bruce spent the rest of his career working with pesticides and studying their use for horn fly control. Research-ers paid little attention to walk-through fly traps, however, until Clyde Morgan and Gus Thomas of the Figure 3. In this close-up view, notice the holes (¼-inch by ½-inch) punched through the apex of the screen inside trapping elements. The flies crawl through these holes and cannot find their way back out. USDA noticed Bruce's paper during the 1970s while they compiled a complete bibliography on the horn fly. By 1986, the problem of horn fl y resistance to pyrethroids was widespread enough in Missouri to warrant re-evaluation of Bruce' s trap design . How the trap works Bruce's trap is a walk-through system (see drawing on back page). Cattle enter through either end, pass through the 10-foot trap and contact a series of strips made of canvas or old carpet. These strips dislodge . most of the horn flies on the animals' backs and sides . Because flies are attracted to light, they travel toward the screened sides of the trap. The animal exits the trap with fewer flies on it, and the trapped flies cannot escape . Repeated use of the trap can reduce the overall local population of horn flies. Three trapping elements along each side of the trap catch flies by the "inverted cone" principle, which makes many insect traps work (Figure 1). The trap forces insects to crawl from a large opening through a small one. A zig-zag screening in the trapping elements functions as the cone (Figure 2). The triangular shape formed by the bending of the screen makes alternate large ends that face the in-terior of the trap and small ends that face the outside of the trap. Holes punched through the small end of the triangle permit the flies to crawl toward the outside of the trap (Figure 3). There, the screening on the exterior of the trapping element interrupts the flies' progress. It traps flies between the exterior screen on one side and the zig-zag screen on the other. Because the cone now faces the wrong way for the insects-that is, the small end faces them-it is unlikely that many will find the holes and escape. G1195 Construction of the trap When building a trap, remember that lumber that is pressure-treated to resist rot will outlast untreated wood and does not require painting. You can use standard-sized lumber, screening and other items where possible. You can get most of the materials easily from lumber yards, farm supplies or hardware stores, and you can get a set of blueprints for the trap by sending $4.69 ($3.00 plus shipping and handling) to Agricultural Engineering Plan Service, Room 205, Agricultural Engineering, University of Missouri-Columbia, Columbia, Missouri 65211. Specify Plan 1-904-C6, "Fly Trap." Placement and operation The Bruce trap is best employed in a forced use situation where cattle must pass through it on a regular basis (Figure 4). In this respect, placement is like that for dust bags and backrubbers. The best site for placement of the trap is between pasture and the source of water. You can often use fence line to route cattle through the trap, and you can easily move electric fencing . As shown in Figure 4, you can use wire cattle panels to funnel cattle into the trap. If you cannot fence the water source off easily, you can encourage use of the trap with mineral blocks or a mineral station . Molas-ses blocks, or addition of loose molasses to mineral, also increases usage. Putting mineral in an enclosure with entry through the trap is an effective technique. If cattle are reluctant to enter the trap, it may be necessary to remove most or all of the canvas strips, and then to replace them one at a time after the cattle overcome their shyness. After cattle are used to the Figure 4 (Left) . In this completed horn fly trap, heavy wire panels funnel cattle through the trap. The trap itself is placed in a fence line with a watering pond on one side. The canvas curtains inside the trap have been removed in this photo-graph . Figure 5 (Below) . The elements can be cleaned while on the trap or can be removed for convenience. Scavenger insects make frequent cleaning of the elements unnecessary. Be careful of wasps that may con-struct nests between the elements. trap, they often pass through it several times per day and seem to realize its benefit. Although the trap design incorporates clean-out doors at the bottom of each trapping element, scaven-ger insects soon inhabit the trapping elements and eat the dead flies (Figure 5). It may be necessary to wash the element screens clear with water if they become clogged with mud and debris. The only other maintenance required is periodic inspection and re-pair of the trap as needed. Performance of the trap Field studies conducted in central Missouri during 1986 indicated the trap produced roughly 50 percent control of horn flies when averaged over the season. This level of control was less than that afforded by insecticidal ear tags and some other treatments, but maintained horn flies below the injury level of about 200 flies per animal. G1195 I ½" Plywood I I Isometric I I I I I Trapping Element (Canvas pieces removed) A cut-away view of the horn fly trap shows how the trapping elements are placed along its side. The frame is made from standard-sized CCA treated lumber, and the end framing is extended laterally to provide stability. The top is made from plywood. The canvas strips have been removed for clarity. ■ Issued in furtherance of Cooperative Extension Work Acts of May 8 and June 30, 1914 in cooperation with the United States Department of Agriculture. John W. Oren, Director, Cooperative Extension Service, University of Missouri and Lincoln University, Columbia, Missouri 65211 . ■ An equal opportunity institution. G1195 New 8/87/6M 

Walk-through trap to control horn flies on cattle

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Walk-through trap to control horn flies on cattle

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