A variety of stinging Hymenopteran insects commonly occur throughout the country and include both social and solitary insects. Honey bees (Apis mellifera), yellowjackets (Vespula spp., Dolichovespula spp., Vespa spp.), bumble bees (Bombus spp.), paper wasps (umbrella wasps; Polistes spp.), and bald faced hornets (Dolichovespula maculata) are social insects. Mud daubers (Subfamilies Trypoxyloninae and Sphecinae), digger wasps (Scolia spp. and Campsomeris spp.), and carpenter bees (Xylocopa spp.) are solitary hymenopterans.
Social hymenopterans live in colonies and are responsible for most stinging incidents (in particular bees and yellowjackets), whereas solitary bees and wasps seldom sting people and are usually not aggressive.
Yellowjackets are ½?¾ inch long and distinguished from other social wasps by their distinctive coloration of alternating yellow and black bands (some species have white or red colorations). Yellowjackets construct new nests each year and are opportunistically built in protected places such as abandoned rodent burrows, decayed tree stumps, and holes in buildings. The nests reach maximum size (3,000 to 15,000 workers) by late July to late September. Yellowjackets are extremely aggressive.
Adult yellowjackets eat food rich in sugars and carbohydrates, such as plant nectar and fruit. Yellowjackets are normally considered beneficial because they also obtain food that is high in protein such as other insects and fish, which they feed to the larvae. When fed, the larvae secrete a sugary substance that is consumed by the adults. This exchange of food between the adults and larvae is known as trophallaxis. In late summer, the normal foods are in short supply. When larvae are not fed, they reduce the sugars given to the adults, making them more aggressive. As a result, yellowjackets scavenge for other food sources, leading to heavier interaction with people. Foods such as carbonated beverages, juices, candy, fish, cakes, and fruit are strong attractants. They are already aggressive as a result of depressed sugars and swatting at them during this season only provokes them.
Yellowjacket problems seem to appear almost overnight during late summer when the size of insect populations and activity peak, usually after the first frost and when prey items or food are no longer available. Yellowjackets are very aggressive, especially when protecting the nest. The act of stinging in most bees and wasps causes release of airborne aggression pheromones (odors) that further enrage the colony. Unlike honey bees, yellowjackets do not have a barbed stinger and an individual can sting a number of times. Nests may be located in holes/voids in buildings, bushes, under eaves, etc. but are also found in the ground or in the roots of dead/rotten trees.
Yellowjackets and similar insects are native species and occur throughout the park. They are attracted to flowering plants, heavy vegetation, disturbed soil, poor grade around structures, garbage cans, and water leaks. Yellowjackets can be found anywhere in the park but become common pests when they establish nests around residences, in water control boxes in the ground, and under buildings.
Yellowjackets, wasps and bees are seldom responsible for direct structural damage, however, when nests become established inside of building walls, entire sections of the wall may have to be removed to extract colonies or abandoned nests. Predators such as woodpeckers often cause direct and serious damage to walls when trying to reach insect combs or larvae.
Stings are very painful and some people are so afraid of being stung they may injure themselves (or cause an accident, such as vehicle) trying to escape flying yellowjackets. A given percentage of people are highly allergic to stinging insects and become very ill or die from only a single sting.
Yellowjackets and other stinging insects may be found inside moving vehicles, which can result in dangerous situations. If this happens, carefully stop the vehicle and allow all passengers to exit on the passenger side. Open all windows and allow the insects to leave. Again, refrain from swatting the insect inside the vehicle.
Take precautions for safety when working in areas that are likely to be inhabited by yellowjackets. If a colony is disturbed, slowly walk away (rapid movements may actually attract more yellowjackets) while covering the face to protect sensitive body areas. Move towards dense vegetation or a vehicle. People that are highly sensitive to insect stings should carry a sting treatment kit when outdoors.
First aid treatment for yellowjacket stings include washing the area with soap and water, applying a cold covering for a few minutes, and some take antihistamines. Seek professional medical help if the following occur:
- Wheezing or difficulty breathing;
- Hoarseness, cough or tightness in the throat or chest;
- Difficulty swallowing or slurred speech;
- Thinking or speech is confused;
- Passed out or very weak; or
- Previous severe allergic reaction (anaphylaxis) to bees, yellowjackets, etc. (not just hives or swelling). Anaphylaxis usually starts within 20 minutes, and always by 2 hours following a sting. If this occurs give epinephrine injection if you have an anaphylactic kit by injecting it into the muscle of the upper thigh.
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