Houseplant pests series part 5: Whiteflies

Last winter, I started a blog series about common houseplant pests. So far, I have written about soil gnats, spider mites, mealybugs and aphids. Today I'm going to talk about whiteflies.

Whiteflies are easy to identify, the adults will fly around when the leaves of the infested plant are disturbed.

Whitefly adults and eggs on underside of leaf

You probably won't even notice the infestation until you disturb the plant, and start choking on a cloud of tiny white bugs. 

<cough, cough>

Whiteflies lay their eggs on the underside of the leaves.

Flip a leaf over and take a close look; the eggs, nymphs and adults are easy to see.

In this picture, you can see the light round circles that dot the leaf (eggs/nymphs), along with the adults (click to enlarge).
 
Whiteflies are usually only a problem on ornamental or tropical plants. I have only had whitefly infestations on my plumeria and my hibiscus plants. They can also be a problem on fruit and vegetable plants, and seedlings.

There are three stages in a the whitefly life cycle; egg, nymph and adult. The full life cycle takes a couple months.

Whiteflies harm the plant by sucking the juices out of the leaves and buds. This feeding occurs during both the nymph and adult stages.

Unfortunately, the nymph form of this pest causes the most damage to the plant. So, by the time you notice the adults, there's already been major damage to the leaves.

Heavy infestations can cause severe damage to the plant. If left untreated, whiteflies will eventually kill the plant. It would take a long time for them to kill a large plant, this is more of a concern on small or weak plants and seedlings.

Where do whiteflies come from? More than likely, they were brought into the house on a newly purchased plant, or from putting a houseplant outside during the summer. They could also easily come through window screens, since they are so small.

Whiteflies on hibiscus leaf

As with any houseplant pest infestation, once you discover whiteflies, you'll want to take action immediately.

In my experience, the easiest and quickest way to get rid of whiteflies is by using a systemic insecticide. The systemic will take a week or so to start working, and the whiteflies will be eliminated. However, like many pests, whiteflies can become immune to pesticides if they are used too often.

There are several ways to control whitefly infestations with organic methods, but you have to be diligent. Whiteflies are difficult to get rid of, especially if you have several houseplants.

Here are some organic ways to control whitefly infestations...

• Use a solution of soapy water and spray it on the leaves of your infested plant (I use 1 tsp of Ivory dish soap per 1 liter of water). If the plant is small enough, bring it to the sink or shower and wash the leaves with this soap and water solution. You can also use rubbing alcohol mixed with water (50/50) to spray on the pests.

Soap and water solution for houseplant pests

• Keep in mind that soap or rubbing alcohol can damage the plant, so it's best to spot check it before using these solutions on the entire plant. 

• Trim heavily infested leaves from the plant and throw them in the garbage (outside the house).

• These homemade sprays have no residual effect, and must be sprayed directly on the pests to be effective. You have to be diligent and spray the plant every couple of days. When you no longer see signs of the whitefly, you can go down to inspecting the plant every week or so for signs of reinfestation.

• Be sure to focus your spray on the undersides of the leaves, this is where whiteflies lay their eggs. These treatments will only be effective on the eggs and nymphs, the adults will fly away from the spray.

• 

  Yellow sticky trap to capture adult whiteflies

  To control the adult population, you can use a yellow sticky trap to catch them. Hang the sticky trap from the top branches of the plant, near the infested area.

• In very heavy infestations, you can use a vacuum to capture the adults as they fly from the plant, but be careful not to suck up your plants leaves in the process. 

• Don't forget to inspect plants that are near the infested plants. Whitefly adults can fly and start laying their eggs on other plants, especially when you start treating the infested plant. Continue to monitor other plants in the area until the infestation is gone.

Pest infestations on houseplants are no fun. Whiteflies are one of the most difficult houseplant pests to eliminate, but it's not impossible. Persistence will pay off. For general pest control and prevention tips, read my Pesty Pests blog post.

Pin It