Thrips are slender, elongate in their bodies and the head is elongate as well. They range in color from black to dark brown to tan to yellowish. They are usually hypognathous. The mouthparts consist of a single stylet on the mandible and two stylets on the maxilla. These form a feeding tube. Thrips have small or large compound eyes, and three ocelli are present in fully winged forms. The abdomen consists of eleven segments, whereby ten segments are visible. In some species, an ovipositor is present on the female. Forewings and hindwings are similar. They are narrow and have a setal fringe. The short antennae are in four to nine segments. The legs are short and have a retractile bladderlike organ. When inflated, this organ provides adhesion to smooth surfaces.
Thrips are found worldwide. There are approximately 5000 species. More than 100 species inhabit the Great Lakes region.
Thrips are found in flower blossoms, on the undersides of leaves, in leaf whorls and axils, under bark, in mosses, in leaf litter and soil, on fungi, and on fruits and flower bulbs.
These insects got through a kind of metamorphosis that is intermediate between simple (or gradual) and complete. The first two stages have no external wings and are larvae. Internally, wings may be developing. In some species, the third or fourth instar, the "prepupa," has external wings, but is inactive and does not feed. The fourth or fifth instar, the "pupa," is sometimes enclosed in a cocoon. After this, the adult results.
Thrips are primarily phytophages; that is, they eat plants and parts of plants, such as pollen, flowers, leaves, fruits, twigs, or buds. They consume flower heads of daisies and dandelions. In addition, they feed on onions, carrots, melons, cucumbers, peas, beans, roses, gladiolus, irises, and mullein. Plant-feeding thrips pierce a hole using their mandibular stylet to suck out the contents of individual cells. Pollen-feeding thrips ingest the contents of individual pollen grains.
Some species that live in litter eat fungi or decaying plant materials. Others are gall inducers. There are some species of thrips that feed on mites, small insect larvae, and other species of thrips.
Some species of thrips aid in biodegradation of organic materials.
Some Thysanopterans are vectors of viruses that damage plants. Many thrips cause damage to important crops of vegetables, fruits, and flowers. In addition, when there is a proliferation in the numbers of thrips in the Great Lakes region, these insects may cause respiratory and skin irritation to agricultural workers. Thrips have been known to bite.
Predatory and scavenger thrips are important eliminators of small arthropod pests and organic remains, respectively.
Although introduced species of thrips have adapted to the Great Lakes region, many species have yet to invade previously glaciated parts north of the Wisconsin glacial maxima.