Egg - Yellowish eggs cannot be seen because they are laid into the plant tissue.
Larva - The larva develop through two instars and are distinctly yellow. Second instars become whitish before molting.
Prepupa and Pupa - Both prepupa and pupa are yellowish, quiescent nonfeeding stages. The antennae and wing pads are typical for most thrips species.
Host Plants - This thrips feeds on almost any flowering plant. Carnations, chrysanthemums, gerberas, geraniums, marigolds, pansies, peppers, tomatoes, and roses are the major host plants.
Damage - The western flower thrips feeds on the flowers and foliage by inserting its modified left mandible into the tissue, and sucking the fluids from cells. Oviposition and feeding scars reduce the aesthetic quality and marketability of ornamental plants. When thrips feed on developing tissues, affected cells are unable to expand, and mature leaves and petals are distorted. When thrips feed on expanded tissue, affected cells become filled with air, which imparts a silvery appearance. This thrips also is an important vector of tomato spotted wilt virus and impatiens necrotic spot virus.
Life History - Females lay eggs in tender plant tissue. The eggs hatch in 2 to 14 days, depending on temperature. First-instar larvae begin feeding on egg eclosion. Second-instar larvae also feed on plant tissue, usually in flowers. These larvae are found in the protection of perianth of the flower or within developing terminal foliage. Late in the second instar they stop feeding and move down the plant to pupate. Thrips develop through two quiescent, nonfeeding pupal stages in the soil, plant litter, or in a protected area on the plant. Adults emerge and resume feeding on flowers, buds, and terminal foliage. The entire life cycle from oviposition to adult emergence can take 12 days in hot weather to 44 days in cool weather.
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