Thrips (the singular form of thrips is also “thrips”) are tiny and slender winged insects that suck the sap from your plants (they suck sap from flowers, leaves and stems). These garden pests are so small that you may not notice them, and they can do a lot of damage before you even realize they’re affecting your balcony garden’s container plants. Of the 5,000 thrips species described, most are considered pests, but some species feed on other insects or fungal spores, and they are considered beneficial insects.
Thrips damage. Most likely the thrips in your container garden will not be beneficial for your plants. They will suck the sap from your plants and leave silver streaks or specks on the plant from where light shines through the empty plant cells. Thrips can spread diseases from plant to plant while they feed, cause stunted plant growth and prevent flowers from blooming.
Thrips are attracted to bright colors, including white, blue and yellow, and they will land on flowers of these colors to feed. There are many different types of thrips, and gardeners often find them on their roses and related plants in the Rosaceae family, on citrus plants and vegetables. Western flower thrips, for example, feed on vegetables, strawberries, peaches and more. Onion thrips and bean thrips feed on vegetables. Citrus thrips feed on citrus and pomegranate, and greenhouse thrips feed on orchid flowers, avocado, azalea, philodendrons, ferns and many more plant species.
Getting rid of thrips. If you see thrips or damage from thrips in your container garden, there are several things you can do to combat them. Some gardeners cover bright blue plastic sheets with a sticky substance (or buy a commercial sticky trap that is blue) in order to attract and trap thrips. Biological control is also possible. Aphid wasps, predatory mites and some other insects may help control thrips populations, and biological insecticides may also help.