A taxpayer who challenges a sales tax coverage by virtue of an exemption or exclusion has the burden of showing that he comes within the exemption upon which he relies. Henderson v. Gill, Comr. of Revenue, 229 N.C. 313, 49 S.E. 2d 754. Exemptions from taxes must be strictly construed in favor of the taxing power. McCanless Motor Co. v. Maxwell, Comr. of Revenue, 210 N.C. 725, 188 S.E. 389. The law imposing the sales and use tax does not define insecticides; so the term must be given its ordinary meaning. Webster’s New International Dictionary, Second Edition, Unabridged, defines insecticide as “An agent or preparation for destroying insects, as an insect powder.” It is apparent from the plaintiff’s evidence that *668 MH-30 is an agent for destroying weeds and plants — a herbicide. MH-30 is no more an insecticide than would be a forest fire which destroyed the balsam firs upon which the woolly aphids feed. The judgment of the court below is

Affirmed.