Another rite of passage in the fall garden and fall picnics and festivals is the appearance of yellow jackets.
Last week I was on campus and there was a tree swarming with yellow jacket wasps. The person working in the garden was concerned that there might have been a nest quite close.
On further inspection, I found the yellow jackets actually feeding on the honeydew excreted by the aphids that were covering the willow tree.
The number of yellow jackets swarming around this tree did appear as if there was a nest nearby but it was not the case.
Aphids are a sucking insect with numerous species that feed on lots of different plants. Most gardeners have experienced aphids on a plant in the garden.
Depending on the species, aphids can be pink, red, black, yellow, green or brown. They feed in groups on plant parts, including roots, stems, leaves and flowers. I have pulled dandelions and found aphids feeding on the root. Unfortunately they don’t kill dandelions — darn.
For the most part, aphids are pretty harmless when there are low populations. Large populations can cause leaf and shoot stunting or yellow leaves. In many cases, pruning the tips of the plant can remove aphids.
Some species of aphids carry viruses and spread from plant to plant. This is a little tougher to control as all it takes is just one aphid to inject the toxins into the plant.
They feed by sucking juices from the plant. Their excretion can sometimes be a bigger problem than their feeding. As aphids suck the juices, they excrete a very sticky substance called honeydew. Then, a fungus called sooty mold grows on the honeydew, turning it black.
This honeydew can be an issue, especially if aphid populations are high and the accumulated honeydew begins to drip on parked cars, benches, tables, etc.
Checking plants on a regular basis is a great way to catch a population of aphids before they are out of control. When there are small populations, prune the tips of plants to physically remove the aphids. In addition, a spray of water will blast the aphids from the plant.
Predators such as lady beetles love aphids and will do a good job of cleaning them from a plant. Lacewing and syrphid fly larvae and soldier beetles are also good predators so look for them as well.
Going back to the yellow jackets on the willow, the yellow jackets were going after the sweet honeydew since this is the time of year they begin to forage for sweets. They also like open soda containers, apples, candy and even sweet-smelling perfume.
The best thing to do when you come across a yellow jacket is to remain very still and back away. Don’t swat or aggravate them and they’ll leave you alone.
Last week I mentioned that I really needed organic matter in the form of leaves and I was overwhelmed with offers. Thanks for the offers and I do have a nice pile of leaves to chop up and add to my compost pile.