This invention relates to a method and device for controlling harmful insects on cattle and other livestock. More particularly it relates to a control device which when attached to the animal's ear, not only controls insects over the head and neck portion of the animal, but provides control over essentially the entire body for extended periods of time.
It is well known that livestock are frequently troubled by various types of insects such as face flies, horn flies, lice, mosquitoes, ticks, etc., which prey upon them causing irritation and sometimes infection of the skin, eyes and ears. This not only results in interference with the animal's normal feeding and grazing habits, but can result in serious illness or even death of the animal, since insects are often carriers of infectious diseases.
In the past a number of methods have been proposed to combat this serious problem. Unfortunately, however, most of these methods have proved less than satisfactory in one or more aspects as discussed below.
One conventional method involves manually treating each animal with an insecticide spray. This method of treatment however is prohibitively expensive when large numbers of animals are involved or when the animals are allowed to graze over a wide area.
Other conventional methods rely on self-application of the insecticide by the animal. These methods typically involve placing an insecticide dispensing device such as "dust bags" or oilers in areas frequented by the animals so that they will come into contact with them, whereupon some of the insecticide will be transferred from the dispensing device to the animal. While these self-application techniques are less time-consuming than individual manual treatment, they are also less reliable since the animal might only infrequently come into contact with the insecticide dispensing devices, and even then the amount of insecticide transferred to the animal might be insufficient, or be unevenly distributed, resulting in incomplete protection.
Another more recently developed technique for controlling insects on livestock is based on the application of slow release pesticide technology to this problem. It is known in the art that slow release pesticide generators can be prepared by mixing certain pesticides with a resinous substance which releases the insecticide over an extended period of time. Such "slow-release pesticidal generators" are described, for example, in U.S. Pat. No. 3,318,769 and U.S. Pat. No. 3,944,662.
Generally the pesticides selected for use in such generators fall into one of two classes: volatile insecticides, such as 2,2-dichlorovinyl dimethyl phosphate (DDVP) and 1,2-dibromo-2,2-dichloroethyl dimethyl phosphate (Naled), which are released from the resinous substance as a vapor and (2) non-volatile insecticides which crystallize from the resinous substance under typical use conditions. Representatives of this latter class of insecticides are 2-chloro-(2,4,5-trichlorophenyl)vinyl dimethyl phosphate (stirofos) and 1-naphthyl methylcarbamate (carbaryl) which are commercially employed in pet collars and tags, as are DDVP and naled.
The application of slow-release pesticidal generators to the control of insects in livestock is disclosed in U.S. Pat. No. 3,765,200 and U.S. Pat. No. 3,942,480 which describe two different insect control devices attachable to the animal ears for the control (repelling) of ticks. The only insecticide specifically disclosed in these patents, however, is the volatile insecticide DDVP. It is also mentioned in U.S. Pat. No. 3,942,480 that all known chemical repellants used for incorporation in plastic material have a relatively short useful life extending not much beyond two to three months thus necessitating the replacement of the insecticide-containing device at relatively short intervals.
The object of the present invention is to provide an insect control device which can be used to effectively control a variety of insect pests including flies (e.g., face flies, horn flies, stable flies, etc.), ticks, lice and mosquitoes on cattle and other livestock for extended periods of time, i.e., up to an entire season, without the need for replacement. "Livestock" as this term is used in the present specification and claims is intended to include cattle, sheep, swine, goats and horses.