University:
Washington State University
Course:
ENTOM 101 | Insects and People: A Perspective
Academic year:

2021
Views:

311

Pages:

2
Author:

Athena Harrison

Thrips Thrips are minute slender-bodied insects belonging to the order Thysanoptera. In our area, they are relatively small (a few millimeters), while there are some in the tropics that reach a half inch long. Thrips have unusual wings that are basically stalks with bristles coming off them (Fig. 1). The mouthparts are also unusual because they are arranged in a cone that protrudes downward from the ventral side of the head. The mouth contains two stylets and a single mandible, which rasps or pierces plant tissues. As cells are ruptured, the liquid is “slurped” up by the insect. Fig. 1. A larval thrips on gladiolus. Fig. 2. Bronzing style feeding damage by thrips on Belladona. Development is transitional between incomplete metamorphosis and complete metamorphosis. The last larval instar (stage) is quiescent and nonfeeding. After this stage, the thrips becomes an adult. Some thrips actually form cocoons, just prior to this stage, in the soil. Thrips may have several generations per year. Damage to plants usually appears as a silvery mottling or blotching. On monocots (i.e. gladiolus) the damage resembles streaking. On some plants, damage may appear like that of spider mite feeding. While thought of as plant pests, some thrips species are predacious. Interestingly enough, some will bite people. Major pest species in our area include western flower thrips, gladiolus thrips, and onion thrips. Managing thrips can be somewhat difficult, particularly when they get into blossoms. Fig. 3. Streaking damage by thrips to gladiolus.