<u>Taphrocerus schaefferi</u> is a leaf miner of yellow nutsedge, a serious weed of many agronomic and horticultural crops. Beetles begin egg-laying in early June; the eggs have an incubation period of 16 days. There are three larval instars, the first two of which consume only the chlorenchyma and upper epidermal cells of the infested leaf. The third instar is responsible for most of the tissue destruction. Approximately one half of the vascular bundles are destroyed. Larvae are cannibalistic and only one larva per leaf can develop. The larval and pupal stadia are 20 and 11 days, respectively. Adults emerge in late July and August. The immature stages are described and illustrated. The life cycle of <u>T. schaefferi</u> is well synchronized with that of its host. The primary mortality factor of the immature stages is two larval and pupal chalcid parasites which account for 74% of the total larval mortality. The total dry weight of plants without leaf miners is significantly greater at the P< 0.05 level than those plants with 5-8 leaf miners present. However, the development of <u>T. schaefferi</u> causes only minimal damage to the host. Mining occurs only in mature leaves, the first and second instar mine is superficial, and the third instar mine occurs near the onset of leaf senescence. As a consequence, the biocontrol potential of <u>T. schaefferi</u> is limited. A survey to detect the presence of <u>Elliponeura debilis</u> Loew (Diptera), a seed feeding chloropid, and <u>Glyphipteryx impigritella</u> Clemens (Lepidoptera, Glyphipterygidae), a leaf miner, was conducted. / Master of Science