More than You Ever Wanted to Know about Aphids
Back east, spring is heralded by the sighting of the first red-breasted robin. In the Southern California rose garden, it seems aphids are the harbingers of spring. Tra la.
Aphids, also called plant lice, come in green, brown, red, pink, black and yellow. There are more than 4,000 documented varieties, named, for the most part, after their plant food of choice; the bane of rose growers is, appropriately, the rose aphid.
Aphids reproduce faster than any other insect. The females survive during winter as eggs, hatching in spring-assuming your dormant oil spraying didn't get them. The first hatched females are called "stem mothers." They bear live young-and this is really diabolical-the young are all female and they're already pregnant with the next generation.
They feed on the sap of the tender new growth at the tips of the canes stunting growth and causing flowers to be deformed. A significant population can severely weaken young and less-than-robust plants.
In addition to weakening plants, aphids excrete a sticky, honeydew-like substance which (a) attracts ants and (b) provides a comfortable culture for the growth of a black, sooty fungus. Ants will actually herd an aphid colony like sheep, and fight off natural predators in order to protect their honeydew larder. Getting rid of the ants if you have them is an important control because it puts nature's food chain back in order and allows ladybugs, green lacewings and other aphid eaters to do your work.
As insect pests go, aphids are wimps. There's no need to get out the heavy-duty insecticide artillery. They can be disposed of by handpicking, or washed away with a good blast from the garden hose. Because they multiply fast, you want to hose them down every three or four days, once a week at a minimum. Washed to the ground, they will not crawl back on the plant by themselves-although ants will carry them and put them back.
If you're of a more vengeful temperament and you want to spray the louse with something stronger than water, insecticidal soap or horticultural oil will do the trick without resorting to more toxic methods. Just because these products are considered environmentally friendly doesn't mean they can be used without proper caution. Follow the instructions and don't neglect your protective gear. Also, both the soap and the oil-sprayed on a hot day-may burn the foliage.
If these measures are too tame and you're hell-bent on chemical warfare-or if you have a very severe infestation or if you're spraying to control another insect pest-pretty much any insecticide will kill aphids.