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Past Articles Library | Organic Pest Control | Thrips

THRIPS
(Thripidae)

Thrips, are tiny insects in the order Thysanoptera, that feed by puncturing plant tissue and sucking out the cell contents. Certain thrips species are beneficial predators, but pest species (often in the family Thripidae) are plant feeders that scar leaf, flower, or fruit surfaces or distort plant parts.

DESCRIPTION

Adults are minute, slender insects 1/50 to 1/25 inch (0.5 to 1 mm) long with narrow fringed wings. They are fast moving and can be yellow, brown or black in color. Nymphs are light green or yellow, and similar to the adults, only smaller.

LIFE CYCLE

Adults overwinter in sod, debris, or cracks in bark, becoming active in early spring. Females lay eggs in plant tissue; eggs hatch in 3 to 5 days. Nymphs feed for 1 to 3 weeks, then rest in soil or on leaves for 1 to 2 weeks before molting into adults. 5 to 15 generations a year outdoors and year-round generations in greenhouses.

PLANTS MOST AFFECTED

Thrips have been collected from 29 plant orders including: various berries, cotton, day lilies, field crops, forage crops, grass flowers, legumes, peonies, privet hedges, roses, trees, truck crops, vines, and weeds. They seem to prefer grasses and yellow or light-colored blossoms. Roses are most susceptible in June.

DAMAGE

Adults and nymphs suck contents of plant cells, leaving a silvery stippling or streaking on leaves. Severe thrip infestations can stunt and distort plants, damage flowers, and scar fruit. Some species can spread tomato spotted wilt virus.

MEANS OF CONTROL

Prevention:

Attract native predators such as lacwings, lady beetles, or minute pirate bugs.

Control:

• Spray dormant oil on fruit trees
  
  
• For onion or western flower thrips, release the predatory mite Amblyseius cucumeris or minute pirate bugs
  
  
• Use sticky bright yellow or blue sticky traps to catch adults
  
  
• Spray insecticical soap or neem oil