How to get rid of aphid infestation

Credit: Flickr / dullhunk

Q: I live in Delta, BC and have several flowering baskets on the railing of our deck. Until recently, they were filling out nicely, but today… not so good. Upon closer inspection, I noticed several plants were infested with aphids—quite a lot of them. Do you know of a kid- and pet-friendly method of ridding our flowering plants of these pests, and discouraging them from returning?

There are several ways to get rid of aphids.

Try spraying them with a solution of 15 mL (1 Tbsp.) dish soap mixed with 1 L (1 qt.) of lukewarm water. Test the solution on a single leaf first to make sure it does not burn the plant’s foliage. Apply the solution with a spray bottle to ensure the leaves are thoroughly covered, and then using fingers gently rub all surfaces of the foliage. Afterward, rinse the plant thoroughly using fresh water. Repeat as necessary.

Conway Lum, plant problem expert, has several suggestions to get rid of and prevent the return of aphids.

Wash them away with a mild stream of water a few times a week early in the day to avoid wet leaves late in the evening.

Planting flowers rich in pollen and nectar (like sunflowers, purple coneflowers, and sweet alyssum) will provide food for beneficial insects. These bugs, such as ladybugs, parasitic wasps, and lacewing, will produce more offspring, which will seek out the aphids for food. Lum says if a spray treatment is used, restrict it to spot treatment to reduce negative impact on beneficial insects. He also warns against excessive fertilizing, which can produce succulent foliage and attract aphids.

Ladybugs can also be purchased at nurseries or ordered online or by mail. Ladybugs can eat several hundred aphids a day. The package of insects should be stored in the fridge and gradually released over four or five days at dusk. Releasing them after a light rain is ideal because ladybugs get thirsty after being in transit and in storage (but keep to the release schedule even if it hasn’t rained). Place them right on or by plants with an aphid infestation so they do not need to search for a food source. There is some disagreement about how many ladybugs to use, but around 1,500 should be plenty for home use in a greenhouse or small garden.

Another method is to squeeze the insects by hand, which can be a quick fix. This does pose a risk of inadvertently killing beneficial insects as well, though, if you’re not careful to identify predators versus the good guys.

Finally, remember that aphids are often attracted to unhealthy plants, so optimizing the health of the aphid-covered plant victim is crucial.