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Wasps

What are wasps?
Wasps are grouped into two categories: social wasps and solitary wasps. Social wasps (i.e., yellow jackets, bald-faced hornets and paper wasps) live in groups, defend their nests and take care of their young together. Solitary wasps (i.e. mud-daubers, cicada-killers, spider wasps, and potter wasps) form individual nests; act non-aggressively unless provoked; and sting to paralyze their prey (flies, caterpillars, spiders, etc.) and to defend their nests.paper wasp

    Paper wasps (Polistes exclamans) are ¾-1" in length and have a slender, spindle shaped abdomen. They are long-legged and variously colored (yellow, brown, black and/or red). Paper wasps prey upon various garden pests. However, they do sting in defense of their nest.

    Yellowjacketsyellow jacket wasp(Vespula spp.) are smaller (½-¾") and much stockier than the paper wasp. They have black and yellow, banded markings on the abdomen. Yellowjackets designate members of their colony to defend the nest and are more aggressive than paper wasps. Colony guards can be disturbed by even the slightest vibration and will defend the nest vigorously and may call upon other members of the colony to attack.

    Bald-faced hornets (Dolichovespula maculata)are also slightly smaller (½-¾") than a paper wasp. bald-faced hornet waspThey are stockier than yellowjackets and are black with white/ivory markings on their face, thorax, and the tip of their abdomen. Bald-faced hornets aggressively protect their nest and also assign guards to guard the colony.

Where are wasps nests found?
Wasp nests can be found in or around building structures, near eves, under shutters, in bushes or shrubs, in wall voids, in attic ceilings, and also underground. Yellowjackets prefer to construct a nest that occupies empty space and often form nests in an abandoned rodent den in the ground, a rotted log, or space in the ceiling of an attic. Paper wasps are more likely to be found under shutters or near the eves of a house where their exposed comb nests can be protected from the elements. Bald-faced hornets prefer to build their nests aerially and are often found in trees or shrubs. However, wasps will occupy any space in which they feel protected and where food and nest building resources are readily available.

What do wasps feed on?
Wasps satisfy their nutritional need for protein by preying on other insects. They feed on a variety of garden pests. The diet of a paper wasp, for instance, includes corn earworms, armyworms, tobacco hornworms, etc., while yellowjackets and bald-faced hornets feed on house flies, blow flies, and harmful caterpillars. Wasps also require sugar and will feed on plant nectar and fruit to satisfy this need. Yellowjackets often scavenge for sugary foods at picnic sites and near garbage disposals. Many summertime picnic-goers endure the pest-like behavior of yellowjackets attempting to carry off pieces of their meal.

What is the wasp life cycle?
The life cycle of a paper wasp begins in the spring when several females construct a nest together. One female succeeds the others and becomes the dominant queen. The queen begins laying eggs. The first generation of wasps is entirely female and is cared for by the other females who helped build the nest. In the late summer, males emerge and mate. Mated females over-winter under leaf litter, stonewalls, attics, etc.

The life cycle of a yellowjacket begins in the spring when a fertilized female builds a small nest and begins laying eggs. She tends to the first generation of larvae until they develop into female workers, which rear consequent larvae and work to add to the nest. Toward the end of the summer, males emerge and mate. Mated females over-winter under leaf litter or in the soil.

The life cycle of a bald-faced hornet begins in the spring when a female builds a small aerial nest consisting of just a few cells. She lays eggs, tends to the larvae, and raises the first generation of female workers. The female workers then take over tending to any subsequent larvae and work to extend the nest. In the late summer, males emerge and mate. Mated females over-winter under leaf litter or in the soil.

What happens during and after a wasp sting?
A wasp's sting injects a pain-causing chemical called melittin. Melittin stimulates the nerve endings of the pain receptors in the skin. A wasp sting begins with a sharp pain that lasts a few minutes and eventually fades to a dull ache. The human body responds to wasp venom by liberating fluid (lymph) that causes redness and swelling at the sting site. Sometimes the skin around the sting site remains tender for several days. If a person has been stung in the past and is stung again by the same type of wasp, their immune response will most likely be heightened, resulting in a larger swelling at the sting site. It is quite likely that the sting site will begin to itch as it heals. It is recommended that people refrain from scratching the site so as not to risk secondary infection.

What should I do if I get stung by a wasp?
Wasps have a lance-like stinger without barbs that can be easily retracted and used to sting repeatedly. After being stung by a wasp, move away from the insect because it can sting more than once.

Once away from the wasp, it is safe to treat the sting. Most non-allergic people will only require simple first aid at home to treat the sting. First, wash the sting site with soap and water and then apply antibiotic ointment and a sterile bandage on top.

Apply ice to the sting site for 20 minutes every hour as needed to reduce swelling and numb the area if it is painful. Place a cloth between the ice and your skin to avoid freezing the skin.

You can take an antihistamine (e.g., diphenhydramine) to relieve itching. You may also want to take ibuprofen or acetaminophen for pain relief as needed. No additional medical care should be necessary.

When should I seek medical attention for a wasp sting?
A person should seek medical attention for wasp stings if any of these criteria are met:

  • a person has been stung previously and experienced a severe allergic reaction to the sting;
  • more than 10 stings are sustained at one time, especially in children and the elderly;
  • the sting occurs in the mouth or throat, especially in children.
  • the sting occurs on the eyeball itself;
  • there is a large localized reaction (e.g., redness greater than 10 inches across) or evidence of infection (increasing pain, swelling, redness, drainage of pus, and fever.

A small percentage of the population is hypersensitive to wasp stings, a condition known as anaphylaxis. These people should carry an adrenaline kit at all times and should seek medical attention immediately after a sting.

What is anaphylaxis?
Allergic reactions to stings can develop anywhere on the body and can range from non-life-threatening reactions, such as hives, swelling, nausea, vomiting, abdominal cramps, and headaches, to life-threatening reactions, such as anaphylactic shock, unconsciousness, difficulty breathing, and blockage of the airway resulting from swelling in the throat. Anaphylaxis is a severe allergic reaction to a bee or wasp sting that occurs in a limited portion of the population (one or two out of every 1,000 people) who are hypersensitive to bee (and wasp) venom. For these people, getting stung by a bee or a wasp can be life-threatening or at the very least intensely uncomfortable. While fewer than 100 fatal reactions to sting venom are reported each year in the U.S., it is imperative that if it is suspected that someone is allergic to sting venom, he or she be evaluated by a physician. If it is determined that he or she is allergic, a physician will most likely prescribe either a "sting kit" which includes epinephrine (adrenaline) loaded in a hypodermic syringe for injection, or an Epi-Pen, which is an auto-injector loaded with epinephrine. Epinephrine is capable of reversing the effects of anaphylaxis.

How can I avoid wasp encounters and/or stings?
To help avoid wasps and getting stung follow the listed precautions:

  • Avoid wearing perfume/cologne or fragrant hair products that smell sweet as it will attract wasps;
  • Avoid wearing brightly colored or patterned clothing. Bright oranges, yellows, and/or blues attract wasps. Floral patters may also attract wasps;
  • Do not swat or move rapidly if a wasp is near you; stay calm and move away slowly;
  • Do not approach a nest; if you do accidentally disturb a wasps' nest, run away from the attacking wasps;
  • Clean up all food and drinks; seal all trash cans; take care to avoid nesting areas; and always remain calm around wasps. They usually only sting when provoked.

What can I do about a wasp nest?
A wasp nest should not be disturbed unless it is a direct nuisance to humans. In the event that a nest needs to be removed, it is always best to consult a licensed pest control operator because they are properly equipped to deal with nest removal in a safe and effective way. However, if you decide to remove the nest on your own, there are several tips to follow:

  • Determine what type of wasp you are dealing with and what type of nest they have created (e.g., enclosed or open, in a tree or in the ground). Should the nest be high up in a tree you might want to reconsider removing the wasps yourself;
  • Exterminate wasps at night when they return to their nests to rest and stay warm. Do not attempt to exterminate the wasps during the day because this is the peak of their activity and you risk not killing all members of the colony.
  • Wear protective clothing (e.g., long sleeves, pants, gloves, and a beekeeper's veil);
  • Contact a licensed pest control operator to discuss the best insecticide to use and the best method of application. Depending on the type of wasp and nest you are dealing with, your options will vary.
  • If you would like to read about some potential extermination options please download the following pdf from Oklahoma University: http://www.okstate.edu/

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Last Updated: June 28, 2006