Thigh: see femur. Thigmotactic: contact-loving: applied to species that tend to live close together or in touch, one with the other. Third longitudinal vein: in Diptera (Will.):= radius 5 (Comst.). Third posterior cell: in Diptera, = 2d medial 2 (Comst.). Third submarginal cross-nervure: in Hymenoptera (North.):= radius 4 (Comst.). Thoracic: belonging or attached to the thorax. Thoracic dorsal bristles: in Diptera, the specialized bristles on the dorsum of the thorax. Thoracic feet: the jointed legs on the thoracic segments of larvae, as distinguished from abdominal or pro-legs. Thoracico-abdominal: the first segment of the abdomen when united with the thorax so as to form part of it: =propodeum. Thoracic pleural bristles: in Diptera, the specialized bristles situated on the pleural region of the thorax. Thoracotheca: = cytotheca: q.v. Thorax: the second or intermediate region of the insect body, bearing the true legs and wings: made up of three rings, named in order, pro-, meso-, and meta-thorax: when the pro-thorax is free as in Coleoptera, Orthoptera, and Hemiptera, the term thorax is commonly used in descriptive work for that segment only: in Odonata, where the prothorax is small and not fused with the larger and united meso- and meta-thorax, the term thorax is commonly used for these latter two united, excluding the prothorax. Thread-plate: an epithelial plate of the embryo from which the terminal threads of the ovarian tubes originate. Thyridial cell: in Trichoptera: the cell formed by the first fork of median vein; the cell behind Thyridium. Thyridiate: applied to a wing vein that at one point seems broken so as to permit of a folding or bending; either to pack into a small compass or to enfold the body. Thyridium -ii: small, whitish or almost transparent spots near the anastomosis of the disc of the wings in some Neuroptera, or in the recurrent veins in the cubital cellule in some Hymenoptera; also the apical margin of the gastrocoeli, often alone visible: in Trichoptera, specifically, a hyaline spot on second fork of median vein. Thyrsus: a cluster. Thysanoptera: fringe-winged: an ordinal term, applied to species with four narrow, similar wings, lengthily fringed; mouth parts fitted for puncturing and scraping; metamorphosis incomplete: the Thripids. Thysanura: fringe-tails; wingless, mandibulate insects without metamorphosis; with anal appendages; body covered with scales; thoracic segments similar. Tiarate -us: turban or tiara-like. Tibia -ae: the shank: that part of the leg articulated to the femur basally and which bears the tarsus at the distal end. Tibial epiphysis: a movable process attached near the base of the inner side of the anterior tibia in many Lepidoptera. Tibial membrane: in male Cicada, the drum-like vibratory membrane that produces the sound. Tip: the extremity; the part furthest removed from the base. Titillator: a small process just below the penis in some Orthoptera.