How to Get Rid of Garden Thrips: 4 Ways to Control Thrips

Thrips are tiny insects that proliferate quickly, and certain species can become an infestation in gardens, farms, and greenhouses. Within the order Thysanoptera, there are more than 6,000 species of thrips. Thrips are very small, often shorter than a millimeter in length.

Many thrips species do not pose a threat to human-cultivated food or decorative plants, but some can become garden pests or crop hazards. Species such as western flower thrips (Frankliniella occidentalis) and onion thrips (Thrips tabaci) can cause significant damage, both by their feeding and as a vector of plant viruses, such as the tomato spotted wilt virus. While feeding, the adult thrips’ mouthparts damage the leaves, causing discoloration, deformation, and other damage.

Thrips have a fast life cycle. Females of plant feeder thrip species will lay eggs on or in the leaves of the host plant. Some species insert the eggs into slits they make in the plant tissue. Thrips hatch, then go through two larval stages, followed by prepupae and pupal stages before becoming adults. Thrips populations proliferate quickly, with many species capable of producing eight generations in a single year. Adults and pupae alike can overwinter in the soil.

If you suspect your plants might have thrips, there are two indications of their presence:

1. 1. Visual identification: Thrips are visible to the naked eye, although the small details that would positively identify them will often require a magnifying glass, and some will even require a microscope. The adults are slender and elongated with narrow, fringed wings. Immature thrips—often called larvae or nymphs—are smaller but still elongated and lack wings. Thrips tend to be translucent white or yellowish, with some being dark brown or black.
2. 2. Leaf damage: If you believe you have harmful thrips, inspect the undersides of leaves and the area where the leaves attach to the stem. The leaves might have galls or growths in the damaged leaf tissue, have a papery texture, feature discoloration, or have tiny pale dots. You may also see damage in the flower buds. In other cases, the leaves will be stunted or distorted.

If your plants might have detrimental thrips, you can try to collect the pests for close inspection. Gently shake the foliage of the affected plant and gather what falls on a light-colored cloth or sheet of paper. Then, you can closely inspect the organisms. You can also capture thrips by hanging sticky traps near the affected plants.

Many species of thrips feed on a wide variety of host plants and cause relatively minor harm. However, some herbaceous decorative plants, houseplants, and vegetable crops are susceptible to thrips damage, so it’s good to be aware of pest control options.

1. 1. Biological control: The best way to prevent a thrip infestation is integrated pest management (IPM), which involves encouraging natural enemies to prey upon or parasitize the harmful thrips. Predatory mites such as the cucumeris mite, green lacewings, ladybugs, minute pirate bugs, and parasitic wasps are all species that can help the control of thrips. (Some of these can also help with other pests, like spider mites). By cultivating plants these predatory species prefer, you can encourage a healthy ecosystem that naturally manages thrips.
2. 2. Cultural control: Diversity of plants is one of the best defenses against pests of all kinds. Often, thrips feed on the weedy species at the edges of row crops or around the perimeter of a garden. To reduce the damage of thrips, keep up with your weeding, avoid excessive use of fertilizer, and encourage diversity by planting a wide variety of different species.
3. 3. Chemical control: Many insecticides are available that will help control a whole host of pests, from thrips to aphids to whiteflies. Systemic pesticides can help control thrips but may also harm beneficial insects and pollinators. However, if the infestation is severe, you can use pesticides such as neem oil, spinosad, and insecticidal soaps. These products are gentler on other organisms.
4. 4. Plant care: You can minimize the harmful effects of thrips by regularly pruning excess leaf matter and disposing of infested plants. Avoid shearing, which is the flat cutting of an entire plant along a single plane, which can spur the tender new growth of thrips, especially in their early life stages. Pay close attention to your plants’ water and soil care to prevent any potential plant diseases thrips might carry.

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