Female macropterous; body color dark brown, almost black, with the joints between femora and tibiae and fore tarsi yellowish; antennae dark brown, apex of segment II and base of III paler; fore wings light brown, darker basally and marginally. Antennae 8-segmented, antennomere III with 2 and IV with 4 sense cones. Head longer than wide, dorsal surface weakly sculptured, lateral margins concave near base and slightly convex from middle of head to the eye; maxillary stylets far apart, V-shaped, extending almost to postocular setae. Pronotum with epimeral and posteroangular setae well developed, remaining setae reduced. Metanotum reticulated, with a pair of short median setae, without campaniform sensilla. Metathoracic sternopleural sutures absent. Pelta triangular and wide, reticulated; abdominal tergites II–VII with 1 pair of wing-retaining setae. Tube nearly cylinder-shaped, a little over 2x as long as basal width, without lateral setae. Fore legs slightly enlarged, fore tarsi with a robust and curved tooth. Fore wings with about 20 duplicated cilia.
Male macropterous, similar to female. Pore plates absent.
Intraspecific variation
Unknown.
Genus and similar species information
Ethirothrips is a genus with almost 60 species, most of them from Asia and Oceania, with a few species probably introduced to the Americas. The species have a lot of morphological variation, thus there is currently no clear diagnosis for the genus. Ethirothrips firmus is one of the few Idolothripinae species in Brazil without metathoracic sternopleural sutures, but with an almost parallel-sided tube, relatively short and without lateral setae. The shape of the head, with sinuous lateral margins, no projection in front of eyes and only one pair of elongate setae, is also helpful in distinguishing this species from other Idolothripinae.
