Thrips alniThrips alniBoth sexes fully winged. Body and legs yellow, major setae light brown; antennal segments IV–VII uniformly brown; fore wings pale to lightly shaded. Antennae 7-segmented; segments III–IV each with short forked sense cone; VII short. Head with 2 pairs of ocellar setae; pair III no longer than distance between 2 ocelli, arising just outside ocellar triangle; postocular setae pair I slightly longer than ocellar setae III, pair II minute. Pronotum with 2 pairs of long posteroangular setae; posterior margin with 3 pairs of setae. Mesonotum with paired anterior campaniform sensilla. Metanotum with irregular longitudinal lines converging to posterior margin, at anterior with curving transverse lines; median setae arising behind anterior margin; campaniform sensilla present. Fore wing first vein usually with 3 setae on distal half; second vein with row of about 15 setae. Abdominal tergite II with 4 lateral marginal setae; tergites V–VIII with paired ctenidia laterally, on VIII posteromesad to spiracles; tergite VIII posteromarginal comb complete, microtrichia long and slender, discal setae S1 as long as setae S2; pleurotergites without discal setae, without microtrichia on sculpture lines or on posterior margin; tergite IX with 2 pairs of campaniform sensilla, X with median split. Sternites without discal setae; median setae on VII arising in front of margin.
Male smaller than female; tergite VIII posteromarginal comb complete medially but microtrichia weak and irregular; sternites III–VI with narrow transverse 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 alni is very similar in colour and structure to the invasive pest species Thrips palmi, the only obvious differences being the greater length of the median pair of setae on tergite VIII of females in alni, and the absence of a pore plate on sternite VII of males.
Feeding and breeding on the leaves of its host plants, and commonly associated with species of Alnus [Betulaceae], but also recorded from Betula and Salix [Salicaceae], all trees of damp woodlands.
Recorded in Britain only from Surrey and Norfolk (Mound et al., 1976), and not since 1966. It is widespread from north-eastern Europe eastwards to Siberia and Mongolia (zur Strassen, 2003).
THRIPIDAE - THRIPINAE
Thrips alni Uzel
Thrips alni Uzel, 1895: 189
Thrips humuli Priesner, 1920: 59
Thrips insperata Priesner, 1927: 418
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.
