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.