Thrips difficilisThrips difficilisBoth sexes either fully winged or hemimacropterous. Body, femora and antennal segments I–II brown to dark brown, tibiae and tarsi, also antennal segments III and IV, yellowish brown; major setae brown; fore wings pale. Antennae 7-segmented; III–IV each with short forked sense cone. Head with 2 pairs of ocellar setae; pair III shorter than distance between 2 ocelli, arising just outside ocellar triangle; postocular setae pairs I–III also short, no longer than ocellar setae III. Pronotum with 2 pairs of posteroangular setae; posterior margin with 3 pairs of setae; discal area with widely spaced transverse striae. Mesonotum with paired anterior campaniform sensilla; median setae arise well in front of posterior margin. Metanotum with irregular reticulation medially; median setae arising behind anterior margin; campaniform sensilla present. Fore wing first vein with 2 (or 3) setae on distal half; second vein with about 9 setae. Abdominal tergite II with 3 lateral marginal setae; tergites VI–VIII with paired ctenidia, on VIII posteromesad to spiracles; III–VII with broadly spaced transverse lines medially between median setal pair; tergite VIII posteromarginal comb absent medially, with a few broadly based microtrichia laterally, discal setae S1 smaller than S2; pleurotergites with no discal setae, posterior margin with a few dentate microtrichia; tergite IX with 2 pairs of campaniform sensilla, X with median split. Sternites with no discal setae; sternite I without small setae at anterior margin; sternite VII marginal setae S1 arise on the margin.
Male brown, smaller than female; tergite VIII with no posteromarginal comb; sternites III–VII each with small oval pore plate.
The genus Thrips is the second largest genus in the Thysanoptera, and currently includes, worldwide, over 290 species. All members of genus Thrips lack ocellar setae I on the head, and they all have ctenidia on tergite VIII posteromesad to the spiracles. Other characters, such as number of antennal segments, number of setae on the fore wing veins, and number of discal setae on the sternites are variable between species (Palmer, 1992; Nakahara, 1994; Mound & Masumoto, 2005). Thrips difficilis is an unusual species within the genus Thrips in that the abdominal tergites have transverse sculpture lines across the median area; moreover, the median pair of tergal setae are considerably smaller than the lateral pairs.
Feeding and breeding on the leaves of its host plants, and specific to various species of Salix [Salicaceae].
Recorded only once in Britain, from a number of adults taken at Ainsdale, Merseyside, in 1924 (Mound et al., 1976); this species is recorded from central and eastern Europe (zur Strassen, 2003).
THRIPIDAE - THRIPINAE
Thrips difficilis Priesner
Thrips difficilis Priesner, 1920: 75
Mound LA & Masumoto M (2005) The genus Thrips (Thysanoptera, Thripidae) in Australia, New Caledonia and New Zealand. Zootaxa 1020: 1–64.
Mound LA, Morison GD, Pitkin BR & Palmer JM (1976) Thysanoptera. Handbooks for the Identification of British Insects 1 (11): 1–79.
Nakahara S (1994) The genus Thrips Linnaeus (Thysanoptera: Thripidae) of the New World. United States Department of Agriculture. Technical Bulletin 1822: 1–183.
Palmer JM (1992) Thrips (Thysanoptera) from Pakistan to the Pacific: a review. Bulletin of the British Museum (Natural History) Entomology Series 61 (1): 1–76.
zur Strassen R (2003) Die terebranten Thysanopteren Europas und des Mittelmeer-Gebietes. Die Tierwelt Deutschlands 74: 1–271.
