Annoying insects are controlled by attaching an insect control device to the body of the animal to be treated. The insect control device is a molded article, preferably in the form of an ear tag, which has been formed from a powder mixture of coumaphos and diazinon, polyvinyl chloride, and a plasticizer. The coumaphos and diazinon are generally used in an amount that would prolong the insecticidal activity without detracting from the suitability of the device.