Abstract
BACKGROUND: The sawfly family Pergidae is best represented in South America, and it is the third largest family in the suborder Symphyta. Tequus is a Neotropical genus that has been reported in association with host plants of the genus Solanum (Solanaceae), with little information about the life history of its members. Tequus schrottkyi (Konow, 1906) was described from Paraguay, without any information about its biology and host plant. NEW INFORMATION: We report the first record of T. schrottkyi from Uruguay, with information on its host plant and details of its biology. The identification was based on morphology, DNA barcode is provided to allow identification using molecular characters. This sawfly species is associated with Solanum commersonii, a native plant common in Uruguay. Tequus schrottkyi presents several generations between March and July. The larvae feed on leaves and spin a silk cocoon in the soil in which they pupate. The adults exhibit sexual dimorphism, the female being larger than the male and with a different color pattern. The eggs are laid individually in the leaf margins into the leaf tissue. The larvae are unpalatable to a generalist predator, possibly due to defensive compounds sequestered from their host plant, known to contain toxic compounds.