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University of Illinois

Be on the Lookout for Bees and Wasps

FOR IMMEDIATE RELEASE
August 29, 2012

It continues to be the time of year when bees and wasps are among the backyard creatures that are commonly encountered, says University of Illinois Extension Horticulture Educator, Candice Miller. "We have had several calls coming into the extension office about people asking what they should do."

Due to the shortage of rain this year, it seems that bees and wasps are being especially attracted to the areas in the yard with the most moisture. Bees for instance, are typically attracted to the garden because of their need for sugar, but they also need water which they use to cool their hive through evaporation.

Besides the cicada killer, yellowjackets are the most likely wasp to see in late summer. Yellowjackets are 1/2-inch-long, black-and-yellow-banded wasps. They live in places such as underground nests, woodpiles, hollow trees or holes in the wall of a building. Late in the summer, nests may contain several thousand wasps. Of the Illinois bees and wasps, this is probably the most likely to sting. Yellowjackets are easily provoked and can sting more than once. They may attack in force if their nest is disturbed.

Here are a few things to look for in your yard:

Ã?· The warning coloration – yellow, orange, and black markings on wasps and bees for example - warns of the ability to sting or bite. Usually, these insects are busy collecting supplies for their nests and are completely uninterested in humans. They will only react if disturbed, captured, or crushed. Learning to leave them alone and moving slowly away is a good strategy.

�· Yellowjackets often nest below ground with an opening near surface rocks, landscape logs, or beneath shrubs. Some social wasps and hornets' nest in hollow spaces in trees, toy chests, and similar places. Seeing them regularly fly to and from a specific spot in the yard suggests a nest. Avoid the area until the presence of a nest can be confirmed and treated.

�· Sweat bees and other insects often land on the skin. Brushing them off is much better than slapping them, which often results in a sting.

�· Sweet drinks and food can attract bees and wasps, especially later in the summer. Keep food and drink covered when outdoors to minimize attraction. Clean up sweet, sticky spills quickly to avoid attracting many unwanted visitors.

�· Sand boxes, especially when used infrequently, provide the loose, well-drained area that ground-nesting bees and wasps prefer. Thoroughly disturbing the sand every couple of weeks should make the area unsuitable for tunneling insects.

�· Awareness, avoidance and prevention can go a long way but dealing with established wasps and hornets is best left to professionals.

It is suggested that you try to eliminate only those wasp colonies that really present a threat. Wasps and hornets are valuable predators of insects, so we shouldn't indiscriminately wipe them out. If a wasp colony is in an area where you can simply avoid it, do so. Mark the spot and just stay away. If the wasps are not causing a problem, the best solution is to wait until the nest is abandoned in the fall. The nest can be safely removed in the winter or, if left alone, will break up during late fall and winter.

Active nests causing problems can be destroyed with an insecticide. Insecticide applications are best made during late evening or cool periods in early morning, when the wasps do not readily fly and most foragers have returned to the colony. A variety of insecticides are currently sold for this purpose with active ingredients including permethrin, deltamethrin, tralomethrin, bifenthrin, tetramethrin, allethrin, and esfenvalerate. Many of these are combination products that include a fast-acting, short-lived ingredient (e.g., allethrin, tetramethrin) with an insecticide that is more persistent in ability to control wasps (e.g., permethrin). Care should always be taken when applying insecticides and the label should be read thoroughly. A professional can always be called to take care of the problem as well.

Commonly sold wasp traps only are effective for yellowjackets. They are not attractive for paper wasps or hornets and will not assist in control of these types of wasps.

If you have further questions about bees and wasps or other home horticulture questions call the Master Gardener Helpline, Monday-Friday 9 a.m. to 11 a.m. at the University of Illinois Extension at (815) 235-4125.

Source: Candice Miller, Extension Educator, Horticulture, mille116@illinois.edu

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