When starting a research program in population ecology, a narrow focus is desirable. If we can understand one focal species well, then it will form the basis for comparative studies on related species. Lessons will be learned on the critical factors in need of study and key features will enable the rapid evaluation of patterns in nature and the processes driving the patterns.

My intent for many years had been to find and study a gall-inducing insect abundant enough locally to enable rapid data collection on questions relating to plant–herbivore interactions, multitrophic level interactions among plants, herbivores and natural enemies, and the distribution, abundance, and population dynamics of species. When I moved to Flagstaff, Arizona, in 1979, I found the species that has become the focus of my studies ever since: a member of the common sawflies, Family Tenthredinidae, Order Hymenoptera. The species has no common name, but its Latin binomial is Euura lasiolepis: eu is Greek for “good” and uro is derived from the Greek for “tail.” Hence, a “good tail” on its only host plant, the arroyo willow, Salix lasiolepis (Family Salicaceae). The fine “tail” is actually a very long, intricately sculptured, saw-like ovipositor used for injecting eggs into the host plant. This is a key feature of the sawfly that affects a female's behavior, its relationship to the host plant, the location of larval feeding sites, and the demography of each generation.