Horsenettle is a persistent, native, perennial weed of pastures and cornfields in southwest Virginia. A survey of insects associated with the weed revealed a number of general feeders, several insect pests of economic plants related to horsenettle, and a few lesser known species. The moth, Frumenta nundinella, demonstrated a high degree of host specificity in the tests conducted The larvae attack the plant in two ways: first instars web the terminal leaves together and form a round hollow chamber within which they feed on the growth tip of the plant, or they enter berries and consume all of the seeds. There are two generations per year, each being about 50 days. The insects overwinter as adults. Females oviposit in the spring and mid-summer. Normally first generation larvae occupy leaf chambers and second generation larvae occupy berries. In the absence of berries, leaf chambers will be formed. Predation, desiccation and interspecific competition with first instars appear to be important mortality factors. Four Hymenopterous parasites were reared from the larval or pupal stages. First generation larvae in leaf chambers significantly reduce (P < .05) dry weight of horsenettle regardless of the number of larvae on the plant. The second generation reduces seed production. E· nundinella was found to be present in 9 counties in western and northern Virginia but population levels were low in all the survey areas. / Master of Science