We studied the insecticidal effect of plant extracts against larvae of Scyphophorus acupunctatus Gyllenhal (Coleoptera: Curculionidae), an important pest of Agavaceae. In the bioassays, the organic extracts of Argemone mexicana L. (Ranunculales: Papaveraceae), Allium sativum L. (Asparagales: Amaryllidaceae), Bursera grandifolia (Schltdl.) Engl. (Sapindales: Burseraceae), Chenopodium ambrosioides L. (Caryophyllales: Amaranthaceae), Prosopis laevigata (Willd.) M. C. Johnst. (Fabales: Fabaceae), and Tagetes erecta L. (Asterales: Asteraceae), which were individually incorporated into artificial diet at 500 ppm, were fed to 1st instars. The variables studied were larval, pupal, and adult weight, and larval and pupal mortality. The extracts of A. sativum, A. mexicana, P. laevigata, T. erecta, and B. grandifolia reduced larval weight by at least 50%. The greatest larval mortality was caused by the extracts of A. mexicana (53%), A. sativum (43%), and T. erecta (43%), whereas the greatest mortality of pupae was caused by extracts of T. erecta. The results suggest that A. mexicana, A. sativum, and T. erecta extracts have the greatest potential for insecticidal activity against S. acupunctatus.