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Sticky mess under the trees

By John Fulton

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[July 29, 2008]  People are beginning to complain about leaking sap coming from trees. Actually this has been going on for a week or so. What happens is a fine mist of sap coats things beneath a tree. This is actually called "honeydew," which is a secretion of sucking insects such as aphids. What makes matters worse is a fungus begins growing in the honeydew, making it turn black.

HardwareThere are two ways to deal with the problem. The first way is to spray the entire tree with a product such as malathion to kill the insects. The second way is to move anything portable from under the tree. If you opt for the first option, you need to make sure you can spray the entire tree. The kind of weather predicted will increase aphid numbers at a very great rate.

The end effect on the tree isn't all that great as long as adequate moisture is available. This means a shot of water when it stays dry for a week or more. We'll also be coming up on lawn fertilization time in about a month, so that fertilizer will help the trees as well.

Aphid eaters

With the numbers of aphids increasing in gardens, on trees and in fields, that brings us to a couple of predators that we are familiar with. One is the Asian lady beetle and the other is the syrphid fly. Both of these increase populations greatly when their food source -- in this case, aphids -- increases.

Auto Repair

We are all familiar with the Asian lady beetle. It is actually a beneficial insect since it eats aphids. It is also a nuisance pest when it gets all over the side of your house or flies around your light over the kitchen table. The vacuum cleaner is the best control in the house, and think twice about treating them outside since they are helping you keep from having black, sticky lawn furniture.

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Syrphid fly is a generic name given to an entire group of flies. There are some differences in appearance and color, but the yellow and black color is the major one in our area. The other names for syrphid flies are hover flies or flower flies. They tend to hover around your arms and face when you have been perspiring, and they land to lap up the sweat. They are also commonly found on flowers -- hence the flower fly name -- and do a good job of pollinating.

Syrphid flies are actually beneficial insects. They help pollinate; larvae feed on dead organic matter; and the larvae are predators of aphids. They cannot sting, but their mouthparts can usually be felt when lapping up sweat from sensitive areas. You may feel a slight pinch.

Grub treatments

With the predominant grub rapidly switching to the larval stage of the Japanese beetle, it's best to hold off grub treatments for at least a couple of weeks. The idea is to get all the eggs hatched before your application.


The eggs of the Japanese beetle and green June bug usually aren't hatched until three or four weeks after the June bug eggs. This would push treatment time to the end of August rather than the beginning. More on grub treatment will follow in a few weeks.

We're at the fair

This is Logan County Fair week. We'll be hard to reach because of the various 4-H shows. If you really need to speak with someone in the office, you may always call the office at 732-8289. You may have to leave a message on the answering machine, but we'll get back to you as we are able.

[By JOHN FULTON, University of Illinois Extension, Logan County]


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