So... What's a Thrip?
There are about 6,000 species of thrips around the world. Most thrips feed on plants by puncturing the outer skin of the plant and sucking out the fleshy contents. Some adults have wings, though those that do are not good at flying and they are often at the mercy of the wind.
Adult thrips are thin and tiny, often being no more than 1/25 of an inch in length. These insects are usually yellow, black or brown in color. Nymphs, the immature thrips, look like smaller versions of the adults and are typically yellow or pale green in color.
Reproduction Patterns of Thrips
In early spring, adults emerge from overwintering and lay eggs in the tissues of plants by cutting the plant open with their ovipositor.
After the eggs hatch – usually in a few days – the nymphs immediately begin eating. They continue to eat as the two-week molting process begins, but, by the fourth and fifth period between molts, feeding stops. Any time during this molting process is a good time to use Safer® Brand NEEM Oil®, which will break the molting cycle and kill them in the process.
Due to their rapid reproduction rates, there can be up as many as 15 generations of thrips in one growing season. More importantly, many species can reproduce asexually, meaning they don’t need a mate.
Thrips live about 45 days and those that are born late in summer will go into diapause until the spring so the species can continue to thrive in the following spring.
Thrips can be found in all regions of North America. Look for them in flower blossoms, under leaves and hiding in bark.
During the spring and summer, these pest insects infest the vegetables, flowers, flowering plants, fruit crops and trees as they feed. They can live in greenhouses throughout the year, where they can quickly reproduce into overwhelming numbers.
To survive the winter, these bugs bury themselves under the debris of plants (often material left over from harvesting) or find shelter underground.
Symptoms of Thrip Damage
Thrips attack plant tissue by sucking out the juices found inside. This activity often creates a mottled appearance on leaves, vegetables and fruit.
Here are some symptoms of thrip infestation:
- Damaged leaves primarily have silver streaks
- Damaged leaves have stippled appearance
- Damaged leaves become papery
- Discolored flower petals, especially on the tips
- Darkened streaks on rose petals
- Stunted and deformed buds and flowers
- Scarred and scabby welts on the skins on citrus and avocado, often silvery
- Scarred apples, nectarines and raspberries
- Scarred grapes featuring light halos around the damage
Results of a Thrip Infestation
When there is a large enough infestation of thrips, the plant can be severely damaged – showing discoloration, scarring and deformity – but a plant will rarely perish as the result.
Fruits and vegetables will not be able to fully mature, and flowers and buds may turn brown and die.
In addition, certain types of thrips can spread fatal plant viruses, including the tomato spotted wilt or impatiens necrotic spot. Try using Safer® Brand Insect Killing Soap to prevent the infestation of thrips and keep your plants looking healthy all season long.
Thrips may also leave excrement on plants. Their frass looks like black, varnish-like flecks that stick to plants.
Plants Favored by Thrips
Thrips are not too picky about the plants they will feed from during their lifetime. In fact, they are known to target more than 500 plants. Here are some of the most common lawn and garden plants for thrips to infest.
Controls for Thrips
Thrips can be a difficult lawn and garden pest to control. These small insects can quickly overwhelm a garden and should be dealt with as soon as they’re discovered.
How Do Thrip Control Methods Work?
Insecticidal soap, made from potassium salt of fatty acids, works by penetrating and destroying the outer shell or membrane of the insect. This action causes the insect to dehydrate and die.
Neem oil products work by suffocating the insect. Remember that when using Neem oil products, there is greater risk of phototoxicity (burning). Avoid using sulfur based fungicides within the active period (5 to 7 days) of the neem oil product.
Warning: Using these two products together can greatly increase the risk of plant burn.
When Should You Begin Thrip Control?
Since Safer® Brand Insect Killing Soap and Safer® Brand End ALL® are contact killers and they do not persist in the environment, several applications may be needed for full thrip control. As a general rule, much like watering, do not use these OMRI Listed® products in the peak of the day or when temperatures exceed 90 degrees F to avoid wilting or browning of the leaves.
Another option for thrip control is to encourage thrip predators, which will stalk and devour these garden pests
Natural enemies of the thrip include lady beetles, parasitic wasps and lacewings. These insects, partnered with a product such as Safer® Brand NEEM Oil® are ideal to help control thrip infestations in your garden.
Lady beetles, parasitic wasps and lacewings will hunt and kill thrips without hurting your plants. When coupled with applications of NEEM Oil®, your thrip problem will be taken care of fairly quickly.
Lady beetles, lacewings and parasitic wasps will appear shortly after the thrips invade your garden. You can also order some of these insects from your local garden center and release them in your garden.
To entice wild predatory insects to stake out territory in your garden, plant nectar- or pollen-producing plants as indicated by the climate and hardiness zone of your area. Most greenhouses and garden centers can help you determine the right plants and planting times for your area.
Environmental Control Options For Thrips
Aside from using Safer® Brand insect control products to manage your thrip problem, you can also make sure your lawn and garden isn’t an inviting environment to these pests.
What Can Stop Thrips?
Make sure your garden, lawn and trees do not provide a favorable environment for thrips to thrive. These insects reproduce rapidly, so its important to act just as quickly.
- Proper irrigation
- Avoid excess nitrogen applications
- Clean up plant waste
- Prune infested plants and buds
- Add row covers
- Install reflective mulch
- Make sure plants are strong and robust
How Does Thrip Control Work?
Pruning the affected vegetation may be helpful in reducing thrips. Cut off the leaves or parts of plantings that have thrips on them.
Check the soil content of your garden or around trees and plantings to make sure you do not have too much nitrogen in the soil. With good intentions, people may use fertilizer that has been highly enriched with nitrogen, only to be inadvertently creating an environment highly conducive to thrips and their offspring.
Plant waste, often left after pruning and harvesting, can be used by thrips to survive the winter or cold snaps, so removing this debris is vital.
Row covers can stop new thrips from arriving. Along the same line, reflective mulch placed under plants can disrupt a flying insect’s ability to locate a new host plant.
Finally, grow young plantings inside until they are strong enough to withstand a thrip attack. If this cannot be done, use a covering for the planting or seedling outside in the garden while it is still young and vulnerable.
When Should Thrip Control Take Place?
Pruning of affected yellowing leaves should be done as soon as they are found. Row covers and reflective mulch should be applied during initial planting or transplanting. Plantings should be started indoors according to the instructions for the plants. This is usually in late winter to early spring, depending on your location.
Waste cleanup should be a year-round effort.