A closer inspection with a magnifier confirms a worrying infestation of minuscule-winged insects – thrips. The plants no longer look healthy, and tiny black specks have appeared on the leaves, which look discolored as well, wilting even.
The fruit and vegetable patches are not thriving either, and those lovely flowers just starting to burst into color are looking rather wan too.
If you are an organic gardener with concerns for the environment, there are many natural ways of dealing with this pest problem.
Here’s how to get rid of thrips naturally.
1. Soap and Water
A quick, easy way using a solution of a little organic liquid soap in a spray bottle and topped up with water.
Mix 5 tablespoons of liquid soap in a gallon of water. This can be sprayed all over indoor or greenhouse plants.
For outdoors, a pump sprayer may be more effective if the infestation is well established. Pour any leftover solution around the base of plants to kill off developing nymphs.
This biological insecticide is processed from a naturally-occurring bacterium found in the soil and used today by farmers for large-scale pest control.
Spinosad is usually combined with other compounds and sold dry or in a dilutable liquid form and is effective against thrips (Thysanoptera).
3. Neem Oil
This is an old established method of destroying many pests, favored by organic gardeners and farmers worldwide. Neem is a natural pesticide derived from the Azadirachta indica, a plant native to India but now cultivated in many tropical regions.
The oil has many beneficial properties and is used in a wide variety of health and beauty products as well as gardening. It has an additional use as a fungicide and helps produce glossy leaves and healthy plants.
As with the soapy water recipe, it can be added to the spray for double effectiveness. Combine 4 teaspoons of neem oil with 2 teaspoons of liquid soap in a gallon of water. Spray liberally.
4. Diatomaceous Earth
Another age-old method of dealing with a multitude of pests and diseases in the house and garden.
Unlike Neem though, it is a preventative or long-term answer to the problem. The white silicon-based powdery substance is made from the crushed fossils of microscopic marine creatures.
Sprinkle around plants. DE is sharp and destructive for many insects who absorb the earth through the cuts in their exoskeletons.
It has a dehydrating effect on the pests, which kills them overtime when they fall to the ground. It can also be spread on soil, pots, or lawn over the winter to disrupt the life cycle of thrips.
After rain or watering the garden, you will need to respray thoroughly.
5. Sticky Traps
These sticky strips are colored to attract different types of pests (blue for thrips).
They can be purchased readily from garden centers, shops and online, and are easy to hang near any infected plants, inside or outside the house.
These critters and other insects will immediately become stuck to the traps and die rapidly without a food source. The strips and pests can then be disposed of.
6. Pyrethrum (Pyrethrin)
This is an organic compound derived from chrysanthemum flowers and toxic to many pests.
Pyrethrin is usually combined with other insecticides and available in commercial sprays. Look at labels to be sure of an organic product.
7. Beneficial Insects
One of the successes of organic gardening is in being able to attract beneficial garden insects that remain unharmed by natural pesticides.
Along with lacewings, mites, and other insects, the star of these predators is the ladybug. Although small and pretty, this little beetle is, in fact, a merciless killer, devouring up to 60 aphids and assorted pests per day.
Pollen and nectar make up the diet, so planting attractive flowers like marigolds and nasturtiums or aromatic herbs will invite these helpers to your garden.
8. Essential Oils
This is a method the gardener can prepare at home. A few drops of essential oil such as peppermint, lemongrass, rosemary, etc., diluted with water is a powerful spray against all types of bad insects.
A standard recipe is 1 to 2 ounces of essential oil in a gallon of water. Spraying the plants thoroughly should kill the pests on contact.
Research into this means of thrip control is ongoing, but plant oils from aromatic herbs seem most successful.
Thunderflies are so lightweight that they are often transported from plant to plant by gusts of wind. It is relatively easy to remove them with a vacuum cleaner that will suction them into a disposable dust bag.
Running a small hand-held cleaner gently along and under the stems and leaves of plants will draw up large numbers of the pests.
10. Eliminate Grass and Weeds
Keeping a ‘clean’ garden is one way of reducing infestations from unwanted insects.
Regular cutting and weeding, and clearing up dead leaves or debris will help keep the numbers down.
11. Kaolin Clay
This natural mineral leaves a grainy residue when puffed onto leaves and fruits, which they cluster around.
Thrips eat into plants and extract the sap causing a great deal of damage. Kaolin clay will help deter them from feeding in this way.
Thrips multiply and spread rapidly, feeding on all kinds of fruit, vegetables, and ornamental plants.
They can damage stems, leaves, and buds, so an infestation might require you to take some fairly radical action.
You may be waiting for those blooms to burst into flower, but pruning hard to cut off the invasion may mean healthy plants, late season.
13. Use the Hose
These bugs are not good flyers and find it even more difficult in moist air. Using the hose to produce a fine mist can restrict their movement.
You may prefer to give them a good drenching to flush them away if the infestation is bad.
There are at least 4,500 types of thrips recorded today and possibly the number is as high as 6000. Some are even beneficial in that they kill and eat other pests, but most are a nuisance to gardeners.
Using these natural methods may mean that next season you will be able to enjoy healthy plants again.