Yellowjackets, Hornets and Mud Wasps
By Bob Chapman
Is there a person reading this that is not familiar with yellowjackets and hornets? It is doubtful, as the yellow and black coloration of yellowjackets and hornets is so distinct. Hornets differ from yellowjackets only in the coloration of the abdomen. Hornets have a large black blotch on the abdomen. Both are referred to in literature as "wasps."
Many a horror story has been told about getting stung by these wasps. There are many, many other wasps, including beneficials, commonly found in the garden but they are not so colorful. The mud dauber wasp, with a dull brown coloration, is quite prevalent in our yards and gardens but they very rarely sting. They lead a very solitary life constructing brood cells of mud and feeding the larvae with partially chewed insects. It's hard for some to believe, but these yellowjackets, hornets and wasps are a desired addition to the garden as they feed on many of the pests found in our gardens.
Life cycle of yellowjackets and hornets.
Yellowjackets, hornets or wasps are relatives of ants and all have constrictions in the center separating the thorax (front) from the abdomen. They are very common during the summer months. Hornets and yellowjackets are known as "paper wasps." These insects are known as "social" insects like the ants, with castes consisting of the queen, female workers and a few males. In the late fall all, or nearly all, of the yellowjackets, hornets and wasps, except the impregnated queen of the colony, will die. The rule is violated in some mild coastal areas of California as some colonies last for several years.
The yellowjacket or hornet queens hibernate all winter, and then emerge when warmer weather arrives to seek a nesting site. The site may be a rodent burrow (preferred by yellowjackets), a tree branch and the outside or inside wall of a structure or some other place (preferred by hornets). Once a suitable site is found she builds a small paper nest in which eggs are laid. The "paper" is made by chewing wood and regurgitating the pulp. One egg is laid in each cell. As she adds more cells around the edge, eggs are deposited. Larvae in the center are older with the younger larvae further out. After the eggs hatch, the queen feeds the young larvae. When the larvae are ready to pupate, cells are covered with silk, forming little domes over the individual openings. Larvae pupate, emerging later as smaller, infertile females called "workers."
In early summer, the adult female workers emerge and assume the tasks of nest expansion, foraging for food, caring for the queen and larvae and defending the colony. The "food" that the yellowjacket feeds on is spiders, flies, caterpillars and many, many other insects.
Yellowjackets are also called "garbage eaters", consuming anything suitable and containing protein for feeding the queen and the young. The food is partially chewed before given to the young larvae. By the end of summer colonies can number in the hundreds or thousands and they look for food containing sugar. This food consists of sweets from such things as ripe fruits and garbage scraps rather than the proteins found in their insect prey.
Taking the "sting" out of summer.
There are several ways to control yellowjackets and hornets.
• To prevent them from bothering an outdoor event such as a picnic, BBQ or family gathering consider using "lure" traps with commercial baits hung on tree limbs or placed on the patio. Hang or place the traps long in advance of the planned event. Many simply use the traps in early summer when the workers are actively seeking "meat," or food to feed their young. The "meat" they need is found in many insects in the garden. Some of their "meat" (insects) is harmful to our plants, some are not harmful and some are beneficials, eating the bad guys. But the workers of the colony do not distinguish between them, feeding on all they find.
• If you see a nest under construction, knock it down. There is very little activity around the newly started nest and they are very hard to find. The queen may start another nest or join an existing nest in the area.
• Water traps are usually homemade and consist of a 5-gallon bucket, string and protein bait (turkey, ham, fish or liver works well). The bucket is filled with soapy water and the protein bait is suspended 1-2 inches above the water. The use of a wide mesh screen over the bucket will help prevent animals from reaching and consuming the bait. The yellowjackets and hornets remove small parts of the bait, fly down into the water and drown.
• Trying to eradicate the few you can see with a pressure or hose-end sprayer with a pesticide does little good. You must find the nest and spray it after dark when all the workers are inside the nest. Once the out-in-the-open nest is located, use an aerosol product that shoots a stream of pesticide 20-25 feet long. These powerful insecticides will kill quickly and they usually contain a freezing agent that stuns any yellowjacket or hornet that happens to be at the entrance to the nest. The insecticide has a 10 day residual. Follow directions on the container for best results. Do not attempt to use this method if you are allergic to bee and wasp stings. If the nest is located in a burrow underground consider using a professional pest exterminator as the nest may be many feet down from the visible entrance and aerosol sprays may not be effective. If the nest is found inside the wall of your home or a structure seek help from a professional exterminator.
• In late summer the yellowjackets and hornets seek a sweet source of food, not needing so much protein as found in their food ("meat") at the height of the season. Containers with a narrow opening and filled with sugar water lure them into the container and they can't escape and drown. Those using homemade traps should use sweet products like jelly, ripe fruit or grenadine syrup. Replace the bait every day. If possible, submerge the trap in water to kill any yellowjackets inside.
• If, during a picnic or barbecuing, hornets or yellowjackets suddenly appear, drawn by the odors, simply take a little chunk of uncooked meat and toss it on the ground about ten feet away. These insects have good eyesight and a keen sense of smell. They will be kept busy taking little bites off the free meal and pay little attention to anyone around.
Personal protection suggestions.
Suggested course(s) of action for those known to be allergic to the stings are:
• You can lesson your attractiveness to these insects by forgoing the use of hairspray, perfume, or aftershave when going outdoors. Bright-colored clothing, such as bright yellow, light blue, red or orange should also be avoided.
• White or tan fabrics are unattractive to yellowjackets and hornets
• Wear shoes when walking through lawns.
• Be cautious when working in the garden, trimming hedges and avoid apple orchards.
• If you do end up in an area where yellowjackets and hornets are present, do not swat them as this will only increase your chance of being stung. Try to calmly walk away. Never crush a yellowjacket. A dying one releases an alarm pheromone that alerts all others in the nest. In just a few moments you could find yourself surrounded by angry yellowjackets.
• At an outdoor event, serve drinks in cups with lids and straws. Don't leave empty plates, cups, food particles or drink cans lying around. Place them in a convenient container with a lid immediately after usage.
What to do if you get stung.
Some have a severe allergic reaction to a yellowjackets sting but most experience a short-term intense sensation. Complications include substantial swelling, tenderness and some itchiness. These conditions disappear after a time. Using OTC oral and topical antihistamines and pain relievers can often help.
Life-threatening allergic reactions can occur with multiple stings and immediate professional health care may be needed.