Two saproxylic forest insects, Hylurgus ligniperda (F.) (Coleoptera: Scolytinae) and Arhopalus ferus (Mulsant) (Coleoptera: Cerambycidae), were reared on artificial or natural diet at 15 or 25^°C to compare larval growth rates and survival. A significant diet by temperature interaction was observed in the growth of H. ligniperda larvae, which developed faster when reared on natural diet at 15^°C, but grew faster and pupated significantly earlier when reared on artificial diet at 25^°C. However, H. ligniperda survival by the end of the experiment was low on both diets when reared at 25^°C (10.1%, 95% CI: 5.2–15.1%), which suggests that rearing at lower temperatures may be required. A. ferus larvae gained significantly larger body size when reared on artificial diet than on natural diet at both temperatures. Survival of A. ferus reared on artificial diet was significantly lower than larvae reared on natural diet at 25^°C. The significant differences between A. ferus larval development rates when reared on artificial and natural diets preclude the use of artificial diet to collect meaningful data to construct temperature development models for ecological comparisons. Artificial diet provided a suitable medium for mass production of individuals for research purposes, e.g., test mortality in response to treatments. However, additional rearing studies are needed to determine whether the larger artificially reared larvae result in adults that are healthier, more productive, and live longer.