Aphids come out in their thousands whenever temperatures are above 50°. They’re kind of amazing; you may see none on your plants one day, and an infestation the next.
In case you’re not sure what they are, let me give you a description. First of all, they’re small, tiny in fact – maybe an eighth of an inch. They come in many colors: white, red, green, dark brown. They’re sapsuckers, so look for them on the most succulent parts of the plant – leaves and tender stems mostly. The leaves’ll often curl around them when the infestation is sufficiently bad. If that weren’t enough, aphids are the major delivery system for plant viruses. See aphids one month, be prepared to find some evidence of a viral problem the next. Not all plant viruses are serious, fortunately. And people cannot catch any plant disease.
But clearly, this is not the sort of damage any gardener wants to see. How tempting to look for an insecticide that’ll just kill them all off! Or even to prevent them from ever landing in our gardens at all.
If you have ants, you aren’t going to prevent aphids. Ants protect the little pests and deliver them to the plant of choice. There is no way that you can, or would want to, get rid of all the ants. You’d drive yourself mad.
There’ve been some terrible results from thinking you can prevent the aphid problem. In Oregon a few years ago, a landscaper got the brilliant idea to deter aphids by applying one of the most potent insecticides we have. Things don’t work that way. He didn’t prevent any aphids, but did kill tens of thousands of bumblebees – pollinators just dropped dead on the parking lot. Aphids didn’t notice; they’re so prolific that killing a few hundred won’t do much.
Another issue with trying to spray the problem away is that not all tiny pests are insects. In some plants, like Italian Cypress, the pest of choice is a mite. Not an insect, so most insecticides won’t work on them. Too often, if you have a mite problem but you kill all the insects, you’re getting rid of nature’s method to control mites.
Complicated enough yet? Just wait.
I’d heard what I’m about to say, but I didn’t believe that aphids were actually born pregnant. I checked a lot of resources, including the National Institutes of health, and yes, they are indeed born pregnant. They can also reproduce the usual way, but still, I find the idea of being born pregnant distressing.
Aphids - you’re not likely to prevent them, and insecticides won’t cure the problem. There is hope, however, and it’s not poison.
Consider soap and water. A tablespoon of dishwashing liquid in a spray bottle with a quart of water. Spray the pests, leave it on for twenty minutes, and rinse off with the hose. Use as hard a spray as you can without damaging the plant. This isn’t magic, but it’s pretty effective if you can repeat it every couple of days.
We’ve all heard about ladybugs and how voracious they are. Indeed, their larvae are sometimes called “aphid lions”. These larvae don’t look at all like their mothers so if you have ladybugs and see an unfamiliar creature (about a quarter of an inch), don’t kill it. It might be one of her hungry babies.
Not only ladybugs’ll eat aphids. Lacewings are lovely delicate insects that will happily chow down on pests. Same thing with praying mantises; they’ll eat almost anything.
The first way to deal with any garden pest is to pay attention. We spend time in the garden to refresh our spirits, make sure to look at the plants while you’re there. Catch the problem when it’s small and it’ll be a lot easier to control. Whether you use hard splash of water with a little soap, neem oil, or natural enemies, you’ll be able to keep pests down to a dull roar.
For KNPR’s Desert Bloom, this is Dr. Angela O’Callaghan of the University of Nevada Cooperative Extension.