THYSANOPTERA Thrips The name Thysanoptera, derived from the Greek "thysanos" meaning fringe and "ptera" meaning wings, refers to the slender wings that bear a dense fringe of long hairs.

Life History & Ecology:

Thrips are generally small insects (under 3 mm).   Most species feed on plant tissues (often in flower heads), but some are predators of mites and various small insects (including other thrips).   Many species are parthenogenetic.   Adults may be winged or wingless.   When present, the wings are slender and rod-like with a dense fringe of long hairs.

Although Thysanoptera are hemimetabolous, many species undergo an extended metamorphosis in which the final immature stage is quiescent, non-feeding, and sometimes even enclosed in a silken cocoon.   This developmental stage, usually called a "pupa", has aroused a great deal of speculation by some entomologists who claim that thrips represent an "intermediate" stage between hemi- and holometabolous development.   A close examination of the thysanopteran "pupa", however, reveals that it does not undergo any internal transformation.   Without additional evidence to support a phylogenetic link to the Holometabola, it would appear that this "pupal stage" may be nothing more than a curious coincidence of convergent evolution.

Distribution:

Common inhabitants of flowers, leaf litter, and fungi throughout the world.

Classification:

Hemimetabola

incomplete development (egg, nymph, adult)

Hemipteroid

closely related to Hemiptera and Psocoptera

The family is divided into two suborders (Terebrantia and Tubulifera).   The suborders can be distinguished by the shape of the last abdominal segment:   short and pointed in the Terebrantia, long and tubular in the Tubulifera.

Physical Features:

Adults: Antennae short, 6-10 segments Head narrow anteriorly forming a conical mouth opening Body cylindrical or spindle-shaped Front and hind wings slender, rod-like, with a dense fringe of long hairs.   Many species are secondarily wingless. Tarsi 1-2 segmented, with eversible adhesive bladders apically Immatures: Structurally similar to adults Always wingless

Economic Importance:

Many thrips are destructive pests of plants, especially grain crops, fruits and vegetables, and ornamentals.   Feeding activities result in plant deformities, scarring, loss of yield, and in some cases, transmission of plant pathogens.   Predatory thrips are beneficial species that may control mites and other small insects.

Major Families:

• Aeolothripidae (Predatory Thrips) -- mostly beneficial species.

• Thripidae (Common Thrips) -- herbivores, including many pests such as the flower thrips (Frankliniella tritici), and the soybean thrips (Sericothrips variabilis).

• Phlaeothripidae (Tube-tailed thrips) -- largest faimly in the order; contains numerous pests as well as a few beneficial species (e.g., the black hunter, Leptothrips mali).

Fact File:

• The word "thrips" is both singular and plural.   There is no such thing as a "thrip".

• Thrips are the only insects that have asymmetrical mouthparts.   Of the three feeding stylets, two are derived from the maxillae and one is derived from the left mandible.   The right mandible disappears during embryogenesis.

• Thrips are able to walk on glassy smooth surfaces because they have an eversible adhesive pad located on the tip of each foot, between the claws.

Hot Links and Illustrations:

• Ecowatch Thysanoptera Page

• Tree of Life Web Project - Thysanoptera

• Discover Life - Thysanoptera

• CSIRO Entomology - Thrips