Order Thysanoptera Thrips

Minute or small, slender-bodied insects with a distinct head, a well-developed prothorax and a long, narrow, 11-segmented abdomen (the first segment greatly reduced and the last modified in association with the external genitalia); cerci absent; wings, when present, very narrow, membranous and strap-like, with few or no veins and marginal fringes of long setae; antennae short, 6-to 10-segmented; tarsi 1- or 2-segmented, each with a protrusible terminal vesicle (the arolium). Mouthparts asymmetrical and adapted for piercing. Metamorphosis gradual; development intermediate between that of hemimetabolous and holometabolous insects, and including an egg, two nymphal and two or three inactive stages (propupae and pupae);3 nymphs similar in appearance to adults but wingless, less strongly sclerotized and with fewer antennal segments; the non-feeding propupae (Fig. 46) and pupae have conspicuous wing pads, and lack the tarsal vesicles found in nymphs and adults; in pupae, the antennae are folded back over the thorax.

Suborder TEREBRANTIA

Thrips with a saw-like ovipositor; tip of abdomen conical in female (Fig. 47a), bluntly rounded in male; wings typically bearing numerous microtrichia; forewings with at least one longitudinal vein extending to the apex. Development includes egg, two nymphal and single propupal and pupal stages. Eggs soft-shelled and usually more or less reniform.

1. Family AEOLOTHRIPIDAE (banded thrips) (p. 89 et seq.)

and with several cross-veins (Fig. 48), antennae usually 9-segmented, body not flattened and ovipositor curving upwards; wings often colour-banded. Includes both phytophagous and predatory species.

EXAMPLE: Aeolothrips tenuicornis (banded-wing flower thrips).

A large and important group of sap-feeding thrips, including many injurious species; the

Fig. 46 Propupa of a thrips - family Thripidae.

Similar to members of the family Thripidae (q.v.) but forewings usually rounded at the apex

3 Presumably in response to the presence of a 'pupal' stage in the life-cycle, some entomologists refer to the active juvenile stages of thrips as 'larvae'. However, this ignores clearly defined structural differences between insect 'larvae' and 'nymphs' which hold sway in the present work (see p. 11).

Fig. 47 Tip of the abdomen of a female thrips: (a) suborder Terebrantia; (b) suborder Tubulifera.

Fig. 47 Tip of the abdomen of a female thrips: (a) suborder Terebrantia; (b) suborder Tubulifera.

Fig. 48 Forewing of a thrips - family Fig. 49 Forewing of a thrips - family Thripidae.

Aeolothripidae.

Fig. 48 Forewing of a thrips - family Fig. 49 Forewing of a thrips - family Thripidae.

Aeolothripidae.

main family of thrips in temperate regions. Forewings usually pointed at apex and each with three longitudinal veins, from which arise numerous, often large, setae (Fig. 49); antennae usually 7- or 8-segmented (rarely 6- or 9-segmented), the last one to three segments forming a thin style; body flattened; female with a downward-curving ovipositor.

EXAMPLES: Frankliniella occidentalis (western flower thrips),4 Thrips tabaci (onion thrips).

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