Anita’s Blog — Nattering Gnats & Devastating Whitefly

In the deathly stillness of a hot, breezeless, cloudless August afternoon, humidity reaching the limits, anyone with a tan might see their skin glow — and that, my friends, is a recipe for a gnat attack!

No tan? No sweat — gnats are attracted to moisture — eyes, nose and ears. There’s no escaping.

“Gnat” is a loose descriptive category, admits Wikipedia, and lists them as any of many species of tiny flying insects in the dipterid suborder Nematocera, especially those in the families Mycetophilidae, Anisopodidae and Sciaridae.

Most people will agree, gnats are annoying. Gnats are most prevalent when the weather is humid and moist,often flying in large numbers called clouds.

They can be both biting and non-biting. Fungus gnats don’t bite, other species of gnats will bite and feed on the blood of people, pets, and livestock.

A female gnat can lay up to 1,000 eggs during its approximately seven- to 10-day lifespan. On a rather interesting note, non-biting gnats’ larvae are laid over water or aquatic vegetation. After about a month, they pupate, rise to the surface of the water and are a nutritious food for fish. Those escaping that food line, of course, hatch and become the pests that bombard your face on a windless day.

Now here’s a mystery solved — if you’ve ever set out a tray of healthy-looking seedlings and discovered them completely gone the next day, quite possibly the delicate greens were eaten by larvae of fungus gnats that burrow into leaves and stems of seedlings — and then into the nice, moist soil, leaving no trace they were ever there and leaving you to wonder how your wee plants disintegrated!

The Internet offers an abundance of remedies for dealing with gnats. Some sites offer lists of scents that gnats hate.

Outdoor gnat clouds

Mix the following with water in a spray bottle and spritz at gnat clouds:

  • Vanilla
  • Citronella oil
  • Rubbing alcohol
  • Lemon Oil
  • Pine oil
  • Can of hairspray — no particular brand, apparently

Before you wage chemical warfare all over your yard, consider this: Gnats can be beneficial as an important food source for birds, bats and larger insects. They also pollinate flowers.

Keeping gnats away from your person may be important to you. There are a number of gnat repellent products on the market, some DEET-free. I’d hesitate spraying any around the face, although that’s mostly where the pesky critters gravitate. Google: gnat repellent products.

Some gardeners attest to putting fabric dryer sheets in your pockets to repel gnats. There was a study . . . . “This study is the first to demonstrate that Bounce® original brand fabric softener dryer sheets repel fungus gnat adults under laboratory conditions.”   

https://www.sciencedaily.com/releases/2010/12/101215102308.htm

Indoor gnat annoyances

Staying indoors during a heavy gnat season isn’t necessarily an escape from gnats. Gnats can get in your house and gravitate toward sink drains, or that lovely bowl of fruit ripening in your kitchen.

Indoors, (I’ve used this successfully) pour an inch or so of red wine in a small jar, cover the jar with plastic wrap, poke a couple of very small holes in the plastic (with an ice pick, if you still have one of those). The gnats can get in but don’t seem to get out. Soon you’ll see dead gnat bodies floating on the surface of the wine. If you’re not sure your wine is sweet enough, stir in a couple teaspoons of sugar.

Another recipe calls for a bowl of vinegar with a few drops of dish soap. Alternately, use that solution in a jar with holey plastic-wrap lid.

Informative gnat site:

https://www.todayshomeowner.com › how-to-control-gnats-outdoors

I’m abruptly changing the subject from annoying gnats to another prevalent pest: devastating whitefly.

It’s cotton harvesting time. As cotton plants are defoliated, whiteflies will be migrating from the cotton fields to the nearest delicate-leaved plants they can find. The field adjacent to our property is planted with cotton again this year.


Cotton Plant

Silverleaf whitefly is most likely the species fleeing cotton fields from the defoliant. You can probably observe the adult whiteflies on the undersides of leaves — they’re about 0.8 to 1.2 millimeters long (0.047 of an inch) with white wings that have no marking, and pale yellow bodies. The wings are held in a roof-like position at about a 45-degree angle over their bodies.

Silverleaf whitefly eggs are oblong, smooth and yellow to amber brown in color and are laid randomly on the underside of leaves.

It’s just as easy to shake a branch of your plant — if itty-bitty white specs fly up, your plant has whitefly. If you live near a cotton field, you might as well prepare to defend your plants.

Silverleaf whitefly host plants include more than 500 species representing 74 plant families. Common hosts are agricultural crops including tomatoes, squash, broccoli, cauliflower, cabbage, melons, cotton, carrots, sweet potato, cucumber, and pumpkin, and ornamental plants such as poinsettiacrepe myrtlegarden roses, hibiscus, lantana, and lilies — Wikipedia.org.


Silverleaf Whitefly on underside of leaf of young Candlebush, senna alata, (legume family)

Several classes of insecticides are labeled for use against whiteflies on ornamental plants. AgriLife Extension recommends chemical control of whitefly, specifically insecticidal soaps and horticultural oils, according to their information page at: https://agrilifeextension.tamu.edu/library/landscaping/whiteflies/

Soaps and oils are among the best alternatives for whitefly control by home owners because they are effective, preserve natural enemies and are relatively safe. It is important to thoroughly cover the underside of leaves and repeat applications.

AgriLife does not recommend broad-spectrum insecticides (those labeled against many pests) because these also kill whitefly predators and parasitoids.

Early evening is the best time to apply insecticidal soaps and horticultural oils. Absolutely avoid applying them during the hottest part of the day and especially if the plants are in sun. If possible, AgriLife recommends watering your plants well one to two days prior to applying pesticide, and to always check the product label for the list of plants that may be injured by the pesticide.

I’d be remiss if I didn’t mention a portion of AgriLife’s disclaimer: “Mention of commercial products is for educational purposes only and does not represent endorsement by Texas Cooperative Extension or the Texas A&M University System.”

For information on whitefly pest management on vegetable gardens and citrus, see Extension publication B-1300.

https://agrilifeextension.tamu.edu/library/landscaping/whiteflies/


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