Ecology & Evolutionary Biology
Thrips Western Flower Thrips - Frankliniella occidentalis 
Description: Female western flower thrips are small, slender, winged insects which are amber or yellowish-brown to dark brown in color. The wings have microscopic fringes of setae. Females are about 1/16 long. Males are similar to females but smaller and always light yellow. Western flower thrips eggs are delicate, cylindrical, slightly kidney shaped, smooth and translucent white. First stage larvae are very tiny, almost worm-like insects that are translucent white. Second stage larvae are also translucent white, but are similar to the adult in size and shape. Both instars have red eyes. Prepupae are similar to second stage larvae except that the wing buds are externally visible. Pupae have longer wing buds and the antennae are folded back over the head. Pupae frequently drop to the soil to pupate. 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 Cycle: Females insert eggs into succulent host plant tissue. Soon, tiny first stage larvae hatch that molt into second stage larvae. These soon molt into a prepupal stage that sometimes drops to the soil. Prepupae do not feed although they can crawl about. In a few days, the prepupae molt into the pupal stage and within a few more days, new adults emerge from the pupal stage. At 86 degrees F, development takes 13 days, and the adults live about 28 days and lay an average of 44 eggs. Larvae of the western flower thrips can become infected with tomato spotted wilt virus or impatiens necrotic spot virus by feeding on an infected plant for only 30 minutes. After a latent period of 3 to 18 days, these thrips can then infect new plants after feeding only 5 to 15 minutes. Only larvae can become infected by these viruses, but adults do most transmission of the disease. Scouting: |
Thrips Biocontrols Insidious Pirate Bug - Orius insidiosus  
Description: Adults are very small (3 mm long), somewhat oval-shaped, and black with white wing patches. Wings extend beyond the the tip of the body. Nymphs are small, wingless insects, yellow-orange to brown in color, teardrop-shaped and fast moving. Both adults and nymphs feed by sucking juices from their prey through a sharp, needle-like beak (the rostrum), which is characteristic of all true bugs.  Life Cycle: The total generation time for Orius in greenhouses (70 deg F) is approximately 3 weeks. Eggs are laid in plant tissue (main stem, leaf veins, flowers or petioles) with the top of the egg sticking out of the leaf. The eggs hatch in 4-5 days and grow through 5 stages. Females lay an average of 129 eggs during their life spans, and adults live about 35 days. Several generations may occur during a growing season. Scouting:
Soil Dwelling Mite - Hypoaspis miles 
Description: The mite is 0.5 mm (1/50 inch) long and light-brown in color. It inhabits the top 1/2 inch layer of soil. Both nymphs and adults feed on soil-inhabiting arthropods, consuming up to 5 prey per day. They survive by feeding on algae and/or plant debris when insects aren't available. Both males and females are present, but males are smaller and rarely seen.  Life Cycle: Females lay eggs in the soil which hatch into nymphs in 1 to 2 days. Nymphs develop into adults in 5 to 6 days. The lifecycle takes approximately 7 to 11 days. Usage: Hypoaspis is primarily a fungus gnat control and cannot be relied on for thrips control alone in a greenhouse. It does, however, improve biological control of thrips when used in conjunction with predators feeding on thrips on the foliage. In small-scale experiments this mite reduced emergence of adult thrips to about 30% of that in controls. Scouting: Thrips Predatory Mite - Amblyseius cucumeris 
Description: Life Cycle: The life cycle of cucumeris begins with small white eggs that can be seen attached to leaf hairs along veins on the lower leaf surface. At 68 degrees F eggs hatch in about 3 days into nonfeeding larvae that molt to nymphs after about 2 days. The 2 nymphal stages which last 7 days, as well as the adult stage which lasts up to 30 days feed on immature stages of thrips. The adult female can lay up to 35 eggs in her lifetime. Adults can eat an average of 1 thrips per day and also feed on two-spotted mites and their eggs.  Scouting: |
