Those Little Blips May Be Pesky Thrips

Ouch! There are tiny, elongated black bugs on everything, including me, and they bite. HELP!

Here we go again, another chapter on bugs. I have been swamped with calls concerning a tiny black insect that bites. What is it, where is it coming from and how do we get rid of it?

These tiny critters are thrips, not to be confused with no-see-ums. Thrips (singular and plural are the same) belong to the insect order Thysanoptera - having fringe or bristle wings. This bit of trivia is only for your information, since thrips are usually so tiny, the entire insect is barely discernible with the naked eye. Taking the time to study wing patterns may not be on your list of priorities as the little beasts scrape and pierce your skin.

The cone-shaped mouth parts, found on the underside of the head, are for piercing, rasping and sucking plant juices. (I see little resemblance between a hairy arm and a flower. But who’s to question the epicurean delights of thrips?) Their feeding frenzy destroys the epidermal cells of the plant. Plant leaves become whitish, misshaped or curled. Flower blossoms and buds may be destroyed and fruit deformed.

You may have had plants attacked by thrips, but didn’t recognize them. Can you recall when the leaves of your gladiola looked a little on the whitish side or the blossoms never really developed? Or have you ever questioned why your geranium flowers shattered or your roses faded before they opened? More than likely, this was the result of thrips. A test for the presence of these intruders is to whack a deformed flower against a white sheet of paper. If your paper suddenly is alive with crawling pencil marks, your plants have a case of the thrips.

The overwintering adult female lays her eggs in the early spring. Some lay their eggs on leaves and/or bark, while other types insert their eggs into the tissue of plants. Many generations may hatch during the summer. When winter approaches, the adults hibernate in the soil, not to appear again until spring.

Thrips can be a very difficult insect to control. The control varies, pesky depending upon whether the thrips are on edible crops or not and whether they are visible or hidden within the plant.

Before sprays are used, whether chemical or organic, make sure the material can be safely used on the plant. Know if the material to be used is a contact insecticide, meaning the thrips must be visible. And, if you are spraying edibles, make sure the product is registered for that use.

Systemic insecticides, such as Orthene or Cygon, help to control thrips that are buried deep inside flower blossoms. Systemics move through the entire plant - roots, stems, leaves and flowers. Because of this, they can NEVER BE USED ON EDIBLE PLANTS. Always read the label, read the label, read the label. Here are a few alternatives to chemical sprays:

1. Control thrips by using insecticidal soaps. But a word of caution: Not all plants can tolerate soap. Product labels will usually indicate which plants can and which cannot.

2. Flood the insects out by spraying the flowers with a water wand.

3. Placing aluminum foil under the plants seems to disorient the thrips and reduce infestations.

4. Set out sticky traps - yellow or blue.

5. Sulfur dust may help but may be toxic to some plants. Try a little on one plant first before dusting all plants.

6. J. Howard Garrett has a few suggestions in his book, “The Organic Manual”: biweekly sprays of fish emulsion and seaweed or a garlic/hot pepper tea; sprays of pyrethrum or liquid kelp; encouraging the natural predator, the green lacewings; and as a last resort, a spray of nicotine sulfate. Nicotine can be very toxic to humans.

Always test these concoctions on one plant before spraying the whole crop, and NEVER use any spray during the heat of the day. Spray early morning or late evening.

As for our skin? Protect it.

And never wear white. White clothes are like a flashing neon sign: “Eats.”

Note: The WSU Master Gardeners will host a free tour of the perennial gardens at Manito Park, Thursday evening beginning at 7. This is a great opportunity to see which perennials are blooming this time of year.