Department of Entomology

Thysanoptera (Thrips)

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Thysanoptera - Brigham Young/VPI & SU PCD0330037

I. Background information

A. Origin of name

1. Latin - thysano, fringe or tassel; ptera, wings
2. Relates to both pairs of wings, when present, being fringed with long hairs.

B. Classification

1. Suborders - 2
a. Terebrantia
b. Tubulifera
2. America north of Mexico - 6 families, 150 genera, 788 species
3. World - ? families, ? genera, 4,500 species
4. Estimate of undescribed species - 25% in N. America, 50% World-wide

C. Common names - Thrips

D. Type of metamorphosis

- Paurometabolous but modified to resemble holometabolism.

E. Phylogenetic relationships

Appear to have evolved from psocopteroid ancestors and related to the Hemipteroids in lacking abdominal cerci. The presence of a pupal stage places them close to the holometabolous orders, along with certain Homoptera that have a pupalike stage.

II. Morphological characteristics

A. Mouthparts elongate into stylets fitted for piercing plant tissue or sucking blood of mites and small insects or plant sap.

B. Either wingless or with two pairs of very narrow wings with veins greatly reduced or absent, each with a fringe surrounding both margins or only the hind margin.

C. Abdomen elongate and usually cylindrical.

D. Adults rarely exceed 2 mm.

III. Biological summary for the order

A. Life history

1. Eggs - Smooth and sometimes about a fifth the size of the female. Only a few are formed at any one time. Laid on leaves, flower parts, and bark. Species with ovipositor insert eggs in plant tissue.
2. Nymphs - Two active feeding instars followed by 2-3 quiescent nonfeeding instars. In Terrebrantia, the third instar nymph forms a prepupa, but is still capable of feeding. The fourth instar is more pupalike and may even form a cocoon. In Tubulifera, the fifth instar is a pupa incapable of feeding. In all cases the nymphs and pupae greatly resemble the adult.
3. Adults - female thrips hibernate. Males unknown in many species. Parthenogenesis common.
4. Several generations per year.

B. Habitat

1. Many species can be found in flower heads
2. Some species under bark, on leaves and fruit, in leaf litter, moss, and flower bulbs, and in the leaf axils of grasses and similar plants.

C. Habits (mode of existence)

1. Phytophagous - suck plant juices from leaves and young shoots of trees and shrubs.
2. Predators - Many species feed on eggs and larvae of various kinds of insects, on mites, and nematodes.
3. Other species feed on fungi and algae in rotting wood and on the juices oozing from rotting wood.

D. Collecting and preserving

1. Searching flowers, foliage, and other plant parts.
2. Beating flower heads over a white cloth.
3. Aspirator or camelšs hair brush.
4. 60 - 70% alcohol
5. Slide mount for identification.

F. Behavior

1. Particularly abundant on the flowers of daisies and dandelions.
2. Attachment devices are present on all species. Lobes modified as a special bladder that is joined to claws modified as a plate. Used to hold thrips firmly to the surface of plants.
3. A few species may bite people.

G. Significance

Many species harmful to cereal crops, field crops, fruits, and garden flowers. Damage crops by direct feeding, forming galls, and transmitting disease (tomato spotted wilt virus).



Prepared by: F. W. Ravlin, VPI & SU
Last modified: 9/3/96