The warm winter was a nice surprise for many Wisconsin residents, myself included. However, with the warmer winter, we’re seeing a lot more insects than we normally would. In previous years, I’ve gotten a few calls about tent caterpillars, scale on magnolia, gypsy moth and a handful of beetles. This year, the aphids take the cake. Starting as early as April, I started seeing samples coming in with curling leaves, silvery “gunk” on the leaves and honeydew spattering leaves, branches and car windshields. Aphids are small insects about 1/8″ long, and pear shaped. They range in colors from green to red to black; I believe the only color I haven’t seen on an aphid is blue.
Aphids will feed on virtually everything in the plant kingdom. Many samples I’ve gotten in range from peach tree leaves to ash trees to a variety of perennials, but that doesn’t begin to list all the plants these colorful insects will feed on. Aphids feed on plants by sucking the “juice” from the inside of the plant leaves, which is why with heavy infestations there is puckering or curling of the leaf. The honeydew I talked about earlier is actually the aphids eating too much and excreting the plant sugars. If the honeydew sits for prolonged periods of time, oftentimes a mold (sooty mold) will form and give the plants an appearance of becoming black.
The good news in all of this is aphids rarely kill a plant. They may stress it a little, but rarely have I seen aphids destroy an entire plant in one season. The easiest thing to do is spray an insecticidal soap on the insects; this will dehydrate them and kill them. A few applications may be necessary to get all of them; one female aphid can give birth to 60-100 nymphs at one time. When spraying, make sure to get the crevices that some may be hiding in, the flowers, the tops of the leaves and especially the bottoms. Many tend to stay close to the outside of the plant and feed on the newest growth, but that doesn’t mean that’s where all of them are located.
One other thing to note is a natural predator of aphids are the lady beetles. I know many people get annoyed with them flying into their homes or how much they stink when crushed; however, I’ve already seen a higher flux in population of these nymphs this spring. I’ve told many people to leave them be- they’re eating the aphids that are in high population this year. Think twice before squashing a bug- you never know what bad insect it preys on!