Answers to Your Questions Beneficial insects Harmful insects Houseplants

Answers to Your Questions : Aphids on Houseplants

Question

My hibiscus and my abutilon spend the summer outdoors. For the past 2 years, I’ve noticed that while they’re in the house, the flower buds are full of aphids and mealybugs. Not on the leaves or stems, but when the flower buds open. This lasts until I take them out in spring for their outdoor season. What do you recommend? I’ve tried insecticidal soap, water jets and sprays with olive oil. All to no avail. Do these little bugs also have anything to do with a small, very long-winged fly that’s been wandering around the house since early autumn? It’s been hanging around the windows of the room where the plants are.

Answer

The sheer number of insects, and their presence only on the flowers, leads me to believe that this is an infestation of aphids rather than scale insects, which are a little slower to multiply and prefer the leaf axils. Aphids prefer soft tissues and proliferate incredibly fast, multiplying tenfold within a week. So, if a single insect survives the treatment, the infestation quickly resumes. The key to controlling them is to be as methodical as possible. Start by showering the plants with a very strong jet, turning them in all directions so that the water can reach every nook and cranny. Now spray with insecticidal soap. Repeat the following week, even if you don’t see any insects, and 2 more times, still on a weekly basis. The more you spray, the more you’ll get rid of the invaders.

Lacewings are beneficial insects that help control aphids. Photo : Mathias Krumbholz

As for the very long-winged fly, it could be a winged aphid (aphids are normally wingless, but do produce winged individuals on occasion, especially in autumn), but their wings don’t usually appear overly long. It’s quite possible that it’s a lacewing, an aphid-predatory insect that often returns to the house in autumn to take shelter from the cold. If so, let them do their work, as they may consume any aphids that escape your treatments.


Larry Hodgson published thousands of articles and 65 books over the course of his career, in both French and English. His son, Mathieu, has made it his mission to make his father’s writings accessible to the public. This text was originally published in Le Soleil newspaper on January 8, 2006.

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, laidbackgardener.blog will continue its mission of demystifying gardening and making it more accessible to all.

2 comments on “Answers to Your Questions : Aphids on Houseplants

  1. Bill Russell

    For whomever does not read French, the secret is to be methodical. The advice is to apply a strong spray with water all over the plant and into every nook and cranny, then spray with insecticidal soap. One week later, repeat even if you do not see any insects. One week after that, do it again. And repeat the treatment two more times (four times in all).

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