What’s Up with All the Wasps?

Wasps are beneficial insect predators and biocontrol agents of many insect and arthropod pests, but during the summer months, social species have the potential to become an urban pest.

Social wasps such as paper wasps and yellowjackets, live in large colonies, compared to solitary wasps, which live and forage alone. Wasps become nuisances when nests are constructed in locations where humans frequent. Only females are capable of stinging and most stings occur when they are in defense mode. This post will shed some light on the most common wasps in our landscape and hopefully help reduce the fear many people have when it comes to stinging insects.

What are the differences between bees and wasps?

Bee bodies are generally hairier and wasps appear smooth and less hairy (which makes bees better pollinators). The wings of bees lie flat over body when at rest, whereas wasp wings will fold into narrow stripes at the sides of their body when at rest. While both adult bees and wasps can be seen foraging for plant nectar, bees feed or provision their young pollen, while wasps feed larvae other invertebrates like caterpillars.

Is it true that wasps are more dangerous that bees?

Some people have a life-threatening anaphylactic response to the venom of bees, wasps or both, making any type of stinging insect a concern. Knowing how correctly identify the insect may help locate potential nesting locations, which may help to manage populations and prevent encounters and stings. Wasps are of greater concern in late summer/early fall when populations are at their highest. During this time, wasps actively forage for food in urban areas near people thereby increasing exposure.

yellowjacket in pop can
Yellowjackets crawl into unattended and open pop cans.

Which stinging insects are considered social?

Social bees include honey bees and bumble bees. Social wasps include paper wasps, and yellowjackets. Social insects live in large colonies and can become aggressive when threatened. They are more likely to be sting hazards because their objective is to protect and defend the nest. It is recommended to avoid known nests and agitating residing colonies.

Is it true that bees can only sting once, but wasps can sting multiple times?

Honey bees can only sting once because they have a barbed stinger, and so when they sting, they lose part of their abdomen, which results in death. Bumble bees, paper wasps, and yellowjackets can sting multiple times, but again, this usually occurs when the nest is threatened or an individual insect is stepped on, swatted, or pressed accidentally against the skin.

How do wasps survive the winter and do they create new colonies each year?

Honey bees are perennial species, and usually survive the winter with the help of beekeepers. Bumble bees, paper wasps, and yellowjackets are annual colonies where a single fertilized female called the “foundress” survives the winter in a sheltered site, which could be the chimney, shed, or mailbox. As the weather warms up in the spring, she becomes active and begins to search for a suitable location to construct a nest. The nest grows full of workers and brood through the summer, with the highest population occurring in August and September. After mating, some fertilized females will overwinter and all other colony members will die. This particular nest is abandoned at first frost and does not get used again (however, a new colony is likely to use this location the following spring).

Where do wasps build their nests so I can try and avoid them?

Paper wasp nests consist of a single-layer of downward-facing, exposed cells which are normally constructed under a horizontal surface like the overhangs of buildings, under decks, tree branches, light fixtures, or inside cavities.

Yellowjacket and hornet nests consist of a series of round combs, stacked in tiers and covered in a paper envelope. They can take the form of a ball-shaped, aerial nest; an underground cavity like former rodent burrow; or inside a wall void, attic, or shed.

Do we have hornets in Nebraska?

People often refer to large wasps as hornets, but true hornets belong to a different genus than paper wasps, yellowjackets, and even the bald-faced hornet (which is actually a yellowjacket). The only hornet established in the United States is the European hornet, Vespa crabro, which is common in the northeast and southeast, but not found in Nebraska.

What is the best way to preventing wasps from nesting near, on, or in your structure?

  1. Inspection: Since wasp nests start off with single queen, the safest thing to do is inspect and monitor prime locations and habitat for nests and knock them down as early in the building process as possible.
  2. Mechanical: Sometimes queens can be eliminated with a fly swatter or be caught and killed to stop her from coming back to rebuild.
  3. Exclusion: Prevent wasps from entering cavities by sealing utility holes, caulking gaps in walls, capping pipes, and other equipment.
  4. Chemical: Some residual insecticide* in sheltered areas may be helpful for deterring wasps from rebuilding in the same spot (*Please read the pesticide label and be mindful of non-target safety).
  5. Cultural and Sanitation: Many wasps are scavengers and will forage on a wide variety of foods, especially sweets in trash cans, open containers, spilled pop, and rotting fruit. Keep food and drink covered when outdoors, discard rotting fruit fallen from plants, and practice proper trash management.
  6. Trapping: Yellowjacket traps can be purchased from hardware store or can be homemade. Most attractive bait will depend on time of year: Bait with meat in spring and early summer and then provide sweets in later summer and early fall.
Yellowjacket traps
Baits for yellowjacket traps.

What should I do if I get stung by a bee or wasp? 

Stings inflicted by bees and wasps are characterized by moderate to severe pain, localized reddening, and swelling, but most people can recover after a few days. In the case of a minor reaction to a bee or wasp sting, wash and clean the area with soap and water, and then apply a cold compress of ice to relieve the pain and ease any swelling.

Honey bees have barbed stingers, which will remain in the skin and continue to release venom until it is removed, so it is important to remove the stinger by scraping it out with a straight-edged object. Some individuals suffer life-threatening anaphylaxis in response to the venom of bees and/or wasps and require immediate medical attention (i.e. EpiPen – Epinephrine).

What should be done if a nest is suspected nearby or find a nest of a stinging insect?

Sometimes honey bees swarm in a tree or shrub and it is best to call a local beekeeper to come and remove them. Bumble bee nests should not be treated unless absolutely necessary, as they are valuable pollinators. The best time to find a wasps nest is during the day when wasps are actively foraging, but it please leave the nest alone. Attempting to approach or treat during the day is not advisable. For yellowjacket nests in wall voids where workers are actively coming in and out of a hole in the wall, do not plug the hole.

Should I call a pest control company for wasps?

Some situations may call for a professional pest management company, especially if sensitive people or children (i.e. childcare facilities) are at risk or if the nest is extremely difficult to reach and treat. Yellowjacket nests located wall voids, attic spaces, or high up on the structure would be a high-risk wasp job. Professionals have ladders, specialized equipment, PPE, and training to complete the job safely during the day.

How can I safely treat small wasps nests myself?

There are many ready-to-use, aerosol insecticides* labeled for wasps that are available at local hardware stores. Many of them can treat the nest from 20 to 30 feet away and some are formulated to produce a foam (*Please read the pesticide label and do not spray indoors!). Here are some tips to follow for DIY wasps control:

  1. Treat at night. This is the most opportune time because temperatures are cooler and all foragers are in the nest.
  2. Wear PPE. Wear protective clothing that covers the body, face, and hands completely.
  3. Use a red light (or disguise beam of flashlight with red cellophane) because wasps cannot see red.
  4. Treat the nest directly and leave the area. For underground yellowjacket nests, foam might work best to move in within the underground space. Cover the entrance hole with a piece of board after treatment.
  5. Check the nest the following day for activity. If it is still active, repeat steps 1 to 5.
OTC Wasps Sprays
Some OTC wasps sprays

When is the best time of the year to treat or remove a wasp nest?

The later in the season you wait to treat your wasp nest, the greater the risk. It is best to treat the nest in late spring when colonies are below peak population numbers and aggressive behavior is not yet evident. If the nests are located in an area away from people and pets, consider leaving it alone until winter and then removing the nest after it has been abandoned naturally.

Small paper wasp nest
Using a red light at night prevents wasps from detecting your presence.

All photos taken by Jody Green.

Resources:

Kalisch et al. 2017. Bees and Wasps Around the Home and Landscape:

 

Jody Green
Extension Urban Entomologist at Nebraska Extension
Jody Green is the extension urban entomologist at Nebraska Extension in Douglas-Sarpy Counties. She specializes in structural, household, and health-related insect pests.
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