Female. Colour: head yellow with dark transverse band, or lower half of head brown. Mesosoma yellow except pronotum, mesoscutal midlobe anteriorly and axilla partly brown. Gaster predominantly brown. Antenna yellow with scape, pedicel, and apex slightly darker. Fore wing with dark band behind marginal vein. Legs yellow.
Morphology: stemmaticum with rugose surface sculpture. Antennal formula 1,1,4,2. Pedicel 0.82-1.11 times as long as F1. F1 3.3-4.0 times as long as its maximum width, shorter than F2 (0.76-1.00) and 0.87-1.10 as long as F3. F2 subequal in length to F3. Flagellomeres with the following numbers of sensilla: F1: 0, F2: 1, F3: 1, F4: 2, F5: 3, F6: 3. Midlobe of mesoscutum with eight setae, side lobes with three setae each. Scutellar sensilla close together, separated by a distance of about the width of a sensillum. Distance between anterior pair of scutellar setae distinctly smaller than between posterior pair. Fore wing 2.6-2.7 times as long as width of disc. Marginal fringe 0.21-0.30 times as long as width of disc. Basal cell with five to eight setae, costal cell distally with two setae. Submarginal vein with two setae, marginal vein anteriorly with six or seven setae. Tarsal formula 5-5-5. Apical spur of midtibia longer than half the length of the corresponding basitarsus (0.61-0.74). Tergites laterally with the following numbers of setae: T1: 0, T2: 2, T3: 2, T4: 2, T5: 3, T6: 3, T7 with four setae. Ovipositor longer than midtibia (1.11-1.29). Third valvula 0.29-0.30 times as long as second valvifer.
Male. Colour similar to female, but mesosoma darker and predominantly brown except the following parts pale: mesoscutellar midlobe posteriorly and postero-laterally, inner posterior corner of axilla, scutellum, and propodeum. Legs pale, femora slightly darkened. Antenna light brown, segments of two-segmented club not fused, but sensilla slightly overlapping.
Species group placement. E. strenua-group
Host. Aleyrodidae: Trialeurodes vaporariorum (Westwood). (This species has been reared from tamarillo heavily infested with Trialeurodes vaporariorum in Pemberton, Western Australia. The vast majority of these were parasitized by Eretmocerus warrae Naumann and Schmidt (Chalcidoidea: Aphelinidae). The lack of additional specimens suggests that E. ustulata may not normally parasitize Trialeurodes vaporariorum)
Australia: South Australia, Tasmania, Western Australia