A new IGR, UC-62644, was bioassayed in the laboratory against 4th-instar larvae of Glyptotendipes paripes and Chironomus decorus. A 25% WP of this IGR was tested against midges in experimental ponds at 25, 50 and 100 g AI/ha (5.5-22.0 ppb), and in a golf course pond at 100 g AI/ha or 16.0 ppb. Impact of UC-62644 on nontarget invertebrates in the midge habitats was also studied. The IGR caused 90% mortality of G. paripes and C. decorus at 3.1-5.7 ppb. In experimental ponds, the WP produced an excellent control of midges. Even the lowest dose induced 99% inhibition of total midge emergence, and control lasted for more than 4 wk. In the golf pond, 56-98% of the total emergence was suppressed for 4 wk. The treatments also caused significant mortality of midge larvae. In experimental ponds, Rotifera, Cyclops spp., Daphnia spp., Chaoborus sp., Baetis sp., Corixids, Notonectids, and Coleopterous larvae and adults were affected but most of the these nontarget invertebrates recovered within 2-3 wk after treatment except for Cyclops spp. and possibly corixids and beetles. Rotifers, Ostracods, and Oligochaetes in golf pond were not affected but Cyclops spp. and Hyalella azteca (Saussure) were sensitive to the IGR. UC-62644 is the most effective IGR thus far tested against Chironomid midges and has moderate and temporary adverse effects on the nontarget aquatic invertebrates.