An inexpensive, simple, chemical control of wireworms in land to be used for vegetable production has long been sought in the Prairie Provinces. Existing methods of control (3, 4, 5, 6) are not wholly satisfactory for row crops. The cultural measures commonly advocated (6) will reduce wireworm infestations sufficiently that cereal crops can be grown without serious damage, but they are not usually sufficiently effective that potatoes or other row crops can be produced successfully. Crude naphthalene is the most satisfactory of the chemical methods recommended (3, 4, 5) but it is too costly for material, is difficult to handle and apply, and is effective only under certain conditions of soil, moisture and temperature. As a result, commercial potato production on the prairies has been restricted largely to districts and fields where wireworms are virtually absent.