Oh, so that's why I've been sweeping up so many leaves lately.

July 31, 2009 10:16 AM

How do I save my house plants from a sudden pest infestation?

One of my house plants has somehow picked up a host of what I suspect are aphids (pictures: 1, 2; correct me if I'm wrong in my ID). They're mostly accumulated on new growth, but the plant is losing both new and old leaves.

I've tried wiping the affected parts down to physically remove the aphids, but I end up knocking off more leaves than I clean, so this doesn't seem like a good long term strategy.

I would spray the whole thing down with a hose, but I don't have a hose (not even a sink sprayer!).

How else can I get rid of these guys? This plant has been with me for a long time, and I feel like a bad parent for letting it get this infested. I'd rather not have to get rid of it.

posted by pemberkins to home & garden (6 comments total)

Ladybugs? Though I don't know if you'd want them in your house. They are cute, however.
posted by elder18 at 10:36 AM on July 31

Fill a spray bottle with a little soap and water, that may help. Another natural alternative is Neem oil, which you mix with water in a bottle and spray on the bugs. It doesn't smell as nice, but it is completely safe and non toxic.
posted by markblasco at 10:38 AM on July 31

Take it in the shower with you to hose it down to wash the aphids off. Then repeated applications of anti-aphid pesticides for a while until the problem clears. You might want to keep it outside and away from your other plants during this.
posted by srboisvert at 10:40 AM on July 31

Depending on the plant and how badly it's infected, you can just pinch off the really badly infested bits and chuck them away. Only do this if it's the type of plant that can cope with loosing a few shoots and leaves. Then spray with soapy water (I think the aim is to wash them off as much as it is to stop them being able to grip), and squish and squish and squish the rest - if you're not too screamish. Keep doing it and in a few weeks they should be gone.

A waterspray bottle is always something useful to have if you're going to be a good houseplant mum, many of them quite like being sprayed with water from time to time.

Ladybirds and their larvae will work on houseplants, but they will also go walk about and disappear. They eat aphids like it's going out of fashion.

Otherwise, if you don't care about chemicals, there's a range of pesticides you can get for aphids, including ones specifically for houseplants.
posted by Helga-woo at 11:17 AM on July 31

A tablespoon of dish soap in a quart of water makes a dilute soapy water solution which, when sprayed on aphids, suffocates them (I think the soap acts as a surfactant which messes with their respiratory mechanisms).

Repeated applications are usually necessary, but I've totally destroyed all aphids within a week using a once daily soap spray.
posted by Aquaman at 11:51 AM on July 31

I think you are correct in identifying the insects as aphids (pic 1) but when I look at pic 2, I am leaning toward scale insect.
Both insects are sap-suckers and secrete honeydew, that sticky, sugary substance that is coating the leaves.
The key in treating your plant is to physically remove/suffocate the insects. Most of the non-toxic sprays and remedies for killing insects are simply coating the insects bodies so that they suffocate. (Insects "breathe" through holes in their exoskeletons called spiracles)
There is a product on the market called Safer that is supposedly non-toxic and definitely safe for houseplants. In addition you can dilute dish-washing liquid in water (1 tablespoon of soap to 1 qt water) and use a spray bottle to apply to the plant. You need to make sure that you spray both the upper and lower surfaces of all of the leaves and the trunk/branches as well. The spray will only work if it actually coats the insect. Wait a few hours then spray fresh plain water onto the plant, otherwise the detergent may burn the leaves. You will need to repeat this weekly as new eggs hatch.
Also, don't worry about the leaves that readily fall off, healthy leaves don't drop that easily, the ones that do are already dead they just haven't turned brown yet.
posted by gammer at 4:57 PM on August 1