The purpose of this letter is to point out deficiencies in technique and philosophy that essentially negate the empirical models that were reported in the Forum section of the February issue ofEnviron. Entomol.(Hilbert, D. W., and J. A. Logan. 1983. Empirical model of nymphal development for the migratory grasshopper,Melanophilus sanguinipes. Environ. Entomol. 12: 1–5). All references herein were cited in the aforementioned paper.