Much like aphids, whiteflies are a scourge in the garden. These tiny pale pests fly around sucking plant juices and spreading diseases. Worse yet, they’re so minuscule that they can fit through a lot of mesh screening. Because of this, the whitefly is also a major problem in greenhouses and indoor growing spaces.
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But don’t panic, you can eliminate these white insects from your greenhouse or garden. Let’s talk about whiteflies, how they multiply, and how to get rid of them!
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Whiteflies Overview
Life Cycle Of Whiteflies
In the latter part of spring, whitefly adults place their eggs on the undersides of leaves. Typically, these are done in concentric patterns, towards the upper portion of the plant. An adult whitefly can produce 200-400 eggs.
Five to ten days later, the whitefly eggs will hatch into whitefly nymphs. In the first instar or larval phase, the nymphs are referred to as crawlers. They move a short distance away from their egg and then flatten against the leaf to feed. There are a total of four instars, but once the crawler has picked its location, it remains there throughout further instars.
These nymphal stages can be hard to identify. Once they’ve stopped crawling and latched onto the leaf, they look very similar to scale insects. Often their coloration blends in with the leaf they’re on, or is slightly paler in hue.
After the nymphal stages have concluded, the whitefly larva will pupate. Within a week, the whitefly emerges from its old skin as a new adult to begin its own egg-laying process. These tiny white flying bugs can live for a couple of months as adults before dying off.
Common Habitats For Whiteflies
Whiteflies live the majority of their lives on or near their host plants. While adults can fly and thus can find new susceptible plants to lay eggs on, the nymphs don’t leave their food source. Then eggs hatch and nymphs emerge.
Nymphs overwinter on their host plants on the underside of leaves, where they’ve latched on to feed. However, they don’t tolerate extremely cold climates well and will die off if they are exposed to freezing conditions.
This makes them a common greenhouse pest, as the climate inside a greenhouse is usually warm enough for them to survive. In fact, there is a particular species of whitefly, the greenhouse whitefly (Trialeurodes vaporariorum) which tends to live most of its lifespan on indoor plants!
Adult whiteflies cannot survive for more than a few days without feeding on plant sap. If you’ve found tiny white bugs on plants, you may have found whiteflies. They may be eating, laying eggs, or sheltering from inclement weather.
What Do Whiteflies Eat?
Both adults and nymphs feed on plant sap. However, different species of whiteflies feed on different kinds of plants. For instance, the cabbage whitefly (Aleyrodes proletella) feeds on brassica species.
There are whiteflies that feed on a wide range of different agricultural crops, including citrus, most vegetables and fruits, and some ornamental plants. Worse yet, whiteflies are a vector for nearly a hundred different plant diseases and can spread those diseases during feeding.
They also leave behind honeydew, a sticky substance that can develop black mold or other fungal issues.
How To Get Rid Of Whiteflies
So now you’re asking how to get rid of whiteflies, I’m sure. While these pests can be tricky to eliminate, especially if they take up residence inside your greenhouse, there are ways to combat them. Let’s go over some of the best white fly treatments and find the right option for you!
Organic Whitefly Control
Before trying more serious white fly treatments, you should begin with something very simple: blast your plants with water. Sometimes, a good hard spray with a hose will knock off the whitefly nymphs. As they don’t move after the creeping phase, they will starve and die. This also works surprisingly well for aphid infestations.
Use a handheld vacuum to suck white flies up! While you have to exercise caution while doing this, a small handheld vacuum can be a very easy way to get rid of larvae, eggs, and the tiny white bugs themselves. Just be careful not to let it suck the leaves off your plants.
A good home remedy for whiteflies on plants is a homemade garlic spray. Garlic can be a particularly pungent aroma, so I don’t recommend this for use inside the house! Even in a greenhouse, the scent builds up. I recommend this only for outdoor use.
An insecticidal soap like Safer Soap can be used to knock down heavy infestations. Insecticidal soaps coat the eggs and larvae with a coating that makes it difficult for them to breathe. It’ll also kill off adult whiteflies.
Horticultural oils are also quite useful on this type of pest. I recommend neem oil or something like Bonide All-Seasons Horticultural and Dormant Spray Oil. Both will smother all life stages of this pest and cause them to die off.
If none of the above work, opt for a pyrethrin-based spray. My preferences are Safer Brand Yard & Garden Spray or Take-Down Garden Spray, both of which contain pyrethrin plus an oily or fatty agent. The fats or oils coat eggs and nymphs and smother them while the pyrethrin poisons all life stages. These are both easy on the plants, too!
Environmental Whitefly Control
If you have tiny white flying bugs in house or greenhouse, or even on outdoor plants in the garden, you can use traps to catch them. My preferred choice is yellow sticky traps. White flies are drawn to the yellow color, assuming it’s a flower. They can’t escape to go and lay eggs.
Natural predators for this white bug include ladybugs, lacewings, and the whitefly parasite (which is a form of beneficial parasitic wasp). By ensuring that you have lots of beneficial insects in your yard and garden, you can quickly deal with infestations. Hummingbirds and dragonflies are also natural predators!
Preventing Whiteflies
Place new infested plants in quarantine for a couple of weeks. I know, it’s difficult to do, but before adding new plants to your garden or your greenhouse, keep them separate and observe them for a little bit. That way, if you develop problems with hidden pests, you’ll be able to deal with them fast. And you won’t introduce the whitefly to your other plants, or create the huge problem of an infested greenhouse!
Using neem oil on your plants will deter whiteflies from laying eggs on them. In addition, the oil will coat the eggs and larvae and smother them. Be sure to thoroughly coat both the bottoms and tops of the leaves as well as their stems for complete coverage.
Try mulching with a reflective mulch fabric. Reflective fabrics are confusing to whiteflies, and they tend to leave even host plants alone.
To gauge if you’ve got a giant whitefly problem, use yellow index cards coated with petroleum jelly. Set them around your plants. While these aren’t as effective as sticky traps, they also can catch white flies and alert you to their presence.
Use Tanglefoot Tangle-Trap around the base of citrus trees, and other plants that develop whitefly infestations. While this sticky gel will not catch many of the white bugs themselves, it will stop ants from getting into the tree.
Ants can farm aphids and whiteflies for the honeydew secretion that they produce. They’re known to protect their honeydew providers from natural enemies. If you reduce the ants in your plants, you can reduce the spread of your whiteflies!
Frequently Asked Questions
Q: Do whiteflies bite people?
A: Unlike the irritating black flies (sometimes called horseflies) that bite, whiteflies are harmless to people. They’re just not attracted to humans or our pets or livestock. Damage from whitefly populations is found on plants only!
Q: How can I deal with whitefly honeydew on my plants?
A: Great question! The white fly releases a sticky secretion called honeydew. Left in place, this honeydew can develop black mold that can inhibit plant growth. A good spray of water should wash it away.
If black mold has formed, you may need to wipe off the mold with damp towels. Once you’ve removed the majority of the mold, spray the plant down thoroughly with neem oil, which should prevent further mold growth.
