They’re Cute, Though

The bugs is comin’! The bugs is comin’! Just as sure as the sun is rising higher in the sky each day, the hope of spring is awakening all sorts of pesky little buggers on houseplants. One by one, they are showing their faces: mites, aphids, mealybugs, scale insects, and white flies.

I’d actually consider whiteflies — the target of today’s hunt — to be cute if they weren’t plant pests. The same surely could not be said for drab mealybugs and scale insects, or for mites, the latter because you can hardly see them at all.

Whiteflies come as close to looking like Tinkerbell as does any creature. I hope you never see a whitefly, but if you do, look closely at how their oversize wings seem precariously perched on their tiny backs. And I do mean tiny; the fully grown insect is a mere one-tenth of an inch long. And what a color for an insect: chalky white from head to tail. When disturbed, the insects flit around like fairies so tiny you could at first mistake them for pieces of lint bobbing around in gentle air currents.

The charm soon wears thin. You tire of the whole family taking to the air like a snow squall every time you approach an infested plant. Don’t take too deep a breath, either, or you might suck some whiteflies into your mouth or nostrils.

They’re Suckers

Whiteflies are as bad for plants as are their near relatives, aphids. An adult female lays a few hundred minuscule, cigar-shaped eggs on the undersides of leaves, and once these eggs hatch, the equally minuscule larvae stick their beaks into the leaf and start sucking sap. Starved plants can turn yellow, wilt, sometimes (admittedly not often) even die.

As if robbing plants of nutrients were not enough, the larvae also excrete honeydew. This honeydew is not bad in of itself, except that it drips all over the plant, then is eaten by a sooty colored fungus which coats, but does not penetrate, the plant. Too much of this sooty mold can actually shade a plant, and, anyway, the sooty covering is not very attractive. It’s also sticky, and makes a carpet or the back of the couch or wherever else it’s dripped sticky and unpleasant to the touch.

Those larvae continue to eat and to molt, at one point even losing both their legs and antennae to become even more inconspicuous as they lodge on the undersides of leaves. No matter, though, it’s the adults flitting about in the air that alerts most people to the presence of whiteflies.

What to Do?

A whitefly may look like Tinkerbell, but she may have to go. I say “may have to go” because plants can tolerate a certain number of whiteflies without suffering significant discomfort. It then becomes more a matter of how many whiteflies we gardeners, rather than plants, can tolerate.

Outdoors, whiteflies rarely cause problems, although they did appear for the first time in my vegetable garden just a few years ago. And they’ve returned every year since to their favorite vegetables which, here at least, are kale and Brussels sprouts. Blasts of water dislodge them if repeated and thorough enough to reach the undersides of leaves included.

A rather droll way to deal with whitefly hot spots indoors or out is with a small vacuum cleaner. Get the bugs flying and then wave the nozzle in the air near them. Empty the vacuum cleaner outdoors (if the weather is cold) or into a bag in your freezer to kill the insects before they get their wits back. 

The usual arsenal is effective against this plant pest. Light oil sprays will smother her, insecticidal soap will collapse her cells, and an insect growth regulator — Enstar, for example — will keep her from growing up. When using any of these treatments, repeat them at intervals in order to target those insects that were not in a susceptible growth stage when you last sprayed.

Whiteflies are especially attracted to the color yellow, so the population can also be brought down with sticky yellow cards placed near infested plants. Buy these cards, or make your own by painting rectangles of Masonite or wood with Rustoleum Yellow No. 659, their most favorite shade of yellow. Coat the cards with Tangletrap or make your own sticky coating by mixing 2 parts of petroleum jelly or mineral oil with one part household detergent. The homemade coating is much easier to remove and replace than the Tangletrap. Whiteflies aren’t strong fliers, so traps need to be placed right near infested leaves.

Tinkerbell even has some of her own special enemies. One is a tiny wasp, called Encarsia formosa, available commercially but more useful in greenhouses than in homes because it needs high heat, humidity, and light to thrive. Ladybugs also enjoy eating them.

Cabbage whitefly & ladybug larvae

Another enemy is a fungus disease named Verticillium lecanii and sold as Mycotal. And finally, if we could only enlist the help of Hook, Captain Hook.