The foliage growth on our landscape plants this spring has been nothing short of phenomenal, thanks to the cooler and wetter weather. All is not paradise, however, as with this rapid growth comes a sudden increase in the aphid population in many gardens.
Aphids are usually the first of the “troublesome” insects to make an appearance in the garden. One day there are none, and the next day there seems to be thousands of the pear-shaped, soft-bodied, sap-sucking, rose-loving beggars on your precious plants.
Believing in the adage that knowledge is power and knowing that many gardeners become traumatized at the arrival of the spring’s first aphids, here are a few hard facts about this much-maligned insect.
There are hundreds of different species of aphids. Some attack only one type of plant, others are not so fussy and can be found on many hosts. They ingest plant sap as it is forced up into the new growth shoots. Leaves can become distorted and aphids will spread viruses which can affect plants.
Aphids reproduce in two ways. Overwintered eggs will hatch out in spring into adult females. These females will not mate, but will give birth to live nymphs throughout the growing season. In fall these same females produce male and female aphids which do mate and then produce eggs that overwinter. Aphids normally don’t fly but if colonies become overcrowded on plants they will develop wings and move on.
Aphids are very attractive food for numerous predatory insects and birds. If you do nothing when the aphid hordes attack they will inevitably disappear. A native midge fly called aphidoletes is one of the most effective predators, and ladybugs, of course, love to feast on aphids.
The sticky substance which often accompanies an outbreak of aphids is a secretion produced by the insect as it feeds. This “honeydew” is harmless but doesn’t do much for the appearance of trees like birch and maples and you definitely don’t want to park your car under a tree that is dripping this substance. Ants are often seen skulking around aphids populations; they are feeding on this honeydew secretion.
A strong blast of water directed at the aphid colony is often enough to control them, particularly if repeated every three of four days. The force of the water will destroy many of them and any aphids that fall off the tree will be in no condition to climb back up and resume feeding.
There are many insecticides which are effective against aphids, ranging from botanical and organic formulations to synthetic chemicals. In most instances you shouldn’t have to resort to these measures to keep aphid populations at a tolerable level.
Over the years I’ve talked to many gardeners who seem bent on destroying every single aphid in their garden. When I tell them to relax and do nothing but wait for the predators to show up and start eating I’m sure they think I’m not all there. But this is almost always what happens. No aphids one day, hundreds of aphids the next, no aphids again a few days later and many happy ladybugs, birds and midge flies, it’s all part of the big plan.
