Thrips/Thripids/Thunderflies/Thunderbugs

Thrips are tiny, slender insects with bordered wings. Other common names for thrips include thunderflies and thunder bugs.

Thrips species feed on a wide variety of both plants and insects by puncturing them and sucking up the contents.

A large number of thrips species are considered pests, because they feed on plants with commercial value.

Some species of Thripids feed on other insects or mites and are considered beneficial, while some feed on fungal spores or pollen.

Pest Species of Thrips

• Avocado thrips (Scirtothrips perseae) attacks the avocado and puts brown scars on the fruit and leaves.
• Bean thrips (Caliothrips fasciatus) attacks beans and some other legumes and gives the plant a brown, distorted leaf and seedling terminals.
• Citrus thrips (Scirtothrips citri) attacks citrus plants by leaving a scabby silvery scar on the fruit.
• Cuban laurel thrips (Gynaikothrips ficorum) attacks the laurel fig and Indian laurel, leaving rolled, podlike, dark, scarred terminals and even galls.
• Greenhouse thrips (Heliothrips haemorrhoidalis) attacks avocado, azalea, hypericum, English laurel and Grecian laurel, photinia, rhododendron, and toyon. The damage is bleached leaves (you'll also find black excrement present on undersides); fruit is covered with scabs.
• Onion thrips (Thrips tabaci) attacks yellow to orangish vegetables including garlic, onion, and pepper, plus many herbaceous ornamentals. Damage is stippled and scarred petals, leaves, and other plant parts, plus distorted terminals.
• Toyon thrips (Rhyncothrips ilex) favors yellow Christmas berry or toyon. It causes crinkled, undersized, sometimes blackened terminal leaves.
• Western flower thrips (Frankliniella occidentalis) attacks many herbaceous ornamentals (impatiens, petunia), vegetables (cucurbits, pepper), fruits (grape, strawberry), and some shrubs and trees (rose, stone fruit), causing stippled and scarred petals, leaves, and other plant parts. It also causes distorted terminals.

Suggested Controls

1. A parasitic wasp, Thripobius semiluteus, that attacks only greenhouse thrips has been effective in controlling this pest in greenhouses and southern California avocado orchards.
2. Narrow-range oil, neem oil, and other low-toxicity insecticides, such as insecticidal soaps, can temporarily reduce thrips populations if applied when thrips and the damage they cause first appear.
3. Reflective mulches, which put light on the underside of plant leaves, are used to repel insect pests and improve plant growth.
4. Row covers, hot caps, and other types of cages can exclude thrips and other pests from vegetables and other young herbaceous plants. Any type of covering that excludes insects but allows light and air penetration can be used. Wood, wire, or plastic frames covered with muslin, nylon, or other fine mesh can be used for several years.
5. Prune and destroy injured and infested terminals when managing a few small specimen plants in the landscape. Regular pruning of infested parts can be especially effective with the gall-making Cuban laurel thrips.

6. These predators controls mites and thunderflies/thunder bugs:

   • predatory lacewings, predatory minute pirate bugs, predatory mites and tiny wasps
   • Anystis agilis and Euseius tularensis predatory mites control citrus thrips
   • Franklinothrips orizabensis and Franklinothrips vespiformis predatory thrips control the avocado thrips and greenhouse thrips
   • Macrotracheliella nigra predatory minute pirate bug controls the Cuban laurel thrips
   • Scolothrips sexmaculatus predatory sixspotted thrips controls the mites primarily, but feeds some on thrips and other pests
   • Thripobius semiluteus nymphal endoparasitic wasp controls the greenhouse thrips

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