Larra bicolor (F.) (Hymenoptera: Sphecidae) is an introduced biological control agent of pest Scapteriscus mole crickets (Orthoptera: Gryllotalpidae) in northern Florida. The pests are of southern South American origin. Larra bicolor is widespread in South America; the imported stock is from Bolivia. Its adults seem to require nectar sources. In South America, Puerto Rico (where it was also introduced from Brazil), and southern Florida (a separate introduction from Puerto Rico), the neotropical wildflower Spermacoce verticillata L. (Rubiaceae) has been observed to be a favored nectar source. In northern Florida (29°N) this wildflower is uncommon, freezes to the ground at first winter frost, and does not flower again until April-May. Nevertheless, where it has been planted in northern Florida, the wasps feed on it throughout the warmer months. Wasps were observed to feed at nectaries of 10 other plant species in northern Florida. Four of these other plants were compared experimentally with S. verticillata, but all received fewer visits from the wasps. Known disadvantages to the use of S. verticillata to augment L. bicolor are that it is not native to Florida, and that it grows vigorously in full sun when its roots are not immersed in water. It has been reported as a minor weed in southern Florida. However, it is the best alternative to attract L. bicolor to places where mole cricket control is needed.