A resident population of the yellow-headed fireworm, Acleris minuta (Robinson) (Lepidoptera: Tortricidae), is established in the commercial nurseries of southwestern Iowa. This species sporadically reaches pest status causing considerable damage to rosaceous and ericaceous plantings;A conceptual life system model has been constructed to explain the bionomics of A. minuta populations. The conceptual model consists of an ovipositional subsystem, a developmental subsystem for larval instars 1-4, a developmental subsystem for larval instars 5, 6, & 7 under a summer and winter color morph scheme, and an overwintering subsystem;Acleris minuta is a multivoltine pest with 4 discrete generations in southwestern Iowa. The adult moths are seasonally dimorphic. Adults from the first 3 generations emerge as orange moths, while adults from the fourth generation emerge as gray moths. Orange moths are capable of mating on day 1 post emergence between the hours of 0500 - 0800 CDST. Gray moths which emerge in the fall are not capable of mating even if environmental conditions are favorable. Apparently, both males and females overwinter and mate in the spring;Larval development proceeds through 5 stadia, 6 stadia, or 7 stadia. Reduced growth rates caused by nutrient deficiencies and other adverse environmental conditions increase the frequencies of supernumerary molts. The 6 and 7 instar modes of development are more prevalent during the fourth generation;Laboratory and ecological life tables have been constructed. Ten species of parasitoids caused significant mortality during 1977 and 1978.