Gardening Columns

Bees and Wasps

First published on garden.org on July 31, 2008, by Suzanne DeJohn

Our daily newspaper recently published an article titled "Summer Pests Are Here," and the first category was Bees and Wasps. The writer describes this scenario: You're out mowing the lawn and all of a sudden you feel the tell-tale sharp pain of an insect sting, followed by several more. The article identifies the culprit: "Bees from an underground nest." And offers this solution: "Use several gallons of a liquid insecticide you can pour down the [nest entrance] hole."

I suppose I can chalk this up to our sound-bite media, but all I can say is, "wow." First of all, the culprit would most likely be yellow jackets, not bees. And there was no mention of less toxic alternatives or of simply avoiding the nest rather than reaching for a pesticide. So, as a former hobby beekeeper and advocate for the North American Pollinator Protection Campaign, I feel it's my duty to stand up for the bees and wasps.

Ground-Nesting Bees and Wasps
If multiple insects are emerging from a single hole in the ground, they're probably yellow jackets, a ground-nesting wasp. Yellow jackets are often confused with honeybees, but honeybees don't nest underground. Here's how to tell them apart:

-- Both have stripes on their bodies. The stripes on honeybees are yellowish to orangish tan and black. On yellow jackets they're bright yellow and black, or white and black.

-- Honeybees have relatively plump and fuzzy bodies. Their hind legs are flattened, and you'll often seed little yellow balls of pollen attached. Yellow jackets are smoother and slimmer with a small, defined waist and thin legs.

-- Honeybees forage for food among flowers. Yellow jackets are predators and scavengers, and eat insects and caterpillars during most of the summer.

-- Honeybees are gentle unless provoked. Bees out foraging will generally sting only if stepped on or swatted. They'll defend their nests, but only from immediate threats. Yellow jackets are aggressive by nature, easily provoked, and will attack in force -- even if the threat is at a distance from their nest. Sometimes, just the sound or vibration of a lawn mower across the yard is enough to trigger an attack.

Other species of bees do nest in the soil, but most are solitary species -- they don't form colonies so you won't see multiple insects emerging from the same hole. (Groups of individuals may nest near each other, however, giving the appearance of a colony.) Solitary bees, such as mining bees, leafcutter bees, and sweat bees, rarely if ever sting and definitely don't gang up on intruders.

Bumblebees nest underground, but they are so big they're easy to distinguish from honeybees and yellow jackets. Bumblebees will respond if their nesting area is invaded, and may pursue intruders trying to leave the area. However, bumblebees never swarm in groups and a colony rarely tops 100 individuals, in contrast to the hundreds or thousands of insects in a yellow jacket nest.

The upshot? Simple observation will help you identify the insects in question and decide what, if anything, to do about them.

Honeybees 101
Honeybees aren't native to this country, but we've become dependent on them to pollinate many crops, especially since populations of native pollinators have declined sharply. They are social insects, living in colonies composed of thousands, or even tens of thousands, of individuals. The colonies overwinter, feeding off the stores of honey they've produced in summer.

Honeybees can only sting once. When a honeybee stings you, its barbed stinger is pulled from its body and becomes lodged in your skin. You feel a sharp sting. The honeybee fares much worse: The detaching stinger rips a hole in its abdomen and the bee soon dies. Honeybees are not aggressive and will avoid stinging you whenever possible. The biggest risk of being stung by a honeybee is if you step on one or disturb a nest; then the bees responsible for guarding the hive will sacrifice their lives to defend it. But this is relatively rare.

If you see a huge mass of bees in the sky or clustered in a tree branch, just stand back and watch this fascinating process. The bees are swarming. They've decided their colony is too large for the hive, so they've created a second queen bee, and half the bees and a queen are off to find a new home. The swarming bees are docile -- they've gorged on honey and don't have a home to defend. Many beekeepers will be glad to come and capture a swarm to add to their hives.

Other Bees
There are thousands of native bee species, most of them solitary. Because they don't have a colony to defend, solitary bees are relatively docile and will sting only if swatted or stepped on.

Be happy if bees of any kind flourish in your garden. They're very important pollinators of a variety of crops. Never try to eradicate a bee nest. If honeybees colonize in an inconvenient location, find a local beekeeper (your Cooperative Extension should be able to refer you) to help.

Wasps 101
Like bees, most wasps are also beneficial. Some species prey directly on insects, including garden pests like caterpillars. Others parasitize their prey, laying eggs on or in them. Some wasp species pollinate plants. And most species will not sting unless provoked. Keep in mind that, in general, wasps are beneficial creatures to home gardeners. Many wasps, such as the mud dauber, are solitary and don't form colonies. Solitary wasps rarely sting.

The stinging wasps home gardeners are most likely to encounter are social wasps -- hornets, paper wasps, and yellow jackets, all of which can sting repeatedly. Hornets produce enclosed, gray, papery nests in trees, shrubs, and under the eaves of buildings. Paper wasps build open-celled nests, often under eaves. Hornets and paper wasps generally don't sting unless provoked, but because they often nest so close to human activity, provocation is hard to avoid. Yellow jackets build nests in abandoned underground rodent tunnels. Of the three, yellow jackets are the most aggressive and will attack for no apparent reason. Yellow jackets are responsible for the majority of stings.

Most members of a wasp colony don't survive through the winter. Only individual fertilized females overwinter, and each begins a new colony in spring. The number of wasps in the colony grows during the summer and reaches dozens or even hundreds of wasps by late summer. This is when wasps are most troublesome and most aggressive. In late summer and fall, yellow jackets' food preference turns from insects to carbohydrates, especially sweets, and they will scrounge at garbage cans and picnic sites.

If possible, leave wasp nests alone. Let them go about their business of preying on pest insects. However, if the nest is in a well-traveled area and poses a risk, you may need to destroy it.

You have a few options for destroying active wasp nests. Apply control measures on a cool evening -- the insects will be back home from the day's foraging, and they're more sluggish in cool temperatures. Always wear protective gear, ideally a beekeeper's attire. And consider the option of hiring a professional.

If it's late in the season, the wasps will be dying off anyway. If you find a wasp nest in winter it's safe to remove it.

Yellow Jacket Control
Here are a few ways to deal with ground-nesting yellow jackets:

Trap them. Commercial wasp traps are effective on yellow jackets, but not on paper wasps and hornets. If set out in spring and early summer, when the population in the yellow jacket colony is small, the traps can help keep the population of a nest in check. Later in the season, placing the traps around the perimeter of an outdoor seating area may help reduce their pestering, but the traps won't do much to reduce the overall population.

Smother them. Mike McGrath, host of WHYY's You Bet Your Garden talk show and former editor-in-chief of Organic Gardening magazine suggests this procedure for smothering a yellow jacket nest: Fill a wheelbarrow with a big load of ice and quickly dump it over the hole on a cool evening after the scouts have gone inside for the night. The cold will prevent them from attacking you. Then cover the hole and the area around it with a heavy tarp weighted down with bricks, a piece of sheet metal, a big wooden board, or other heavy object. Then cover that with soil or wood chips. Or cover the hole with a thick piece of clear plastic, seal the edges tight to the ground, and the nest will cook in the sun once the ice melts.

Boil them or bathe them. Some gardeners report success with pouring 10-plus gallons of boiling water into the nest. Other say soapy water does the same thing.

Spray them. Numerous wasp control sprays are available, including organic ones with mint oil as the active ingredient. If you choose to spray, follow label directions very carefully, taking all precautions.

Do NOT pour gasoline into the hole. It's a fire hazard, and if it doesn't kill on contact, it will infuriate the insects. Also it will poison the soil.

No matter what method you choose, know that being stung is a likely outcome.

Paper Wasp and Hornet Control
Control of these aboveground dwelling insects is a bit different:

Remove the nest. It's possible, but risky, to remove paper wasp and hornet nests. On a cool evening when wasps are back in their nest, surround the nest with a very sturdy plastic bag, then cut it off where it's anchored. Freezing wasps for several hours will kill them. You may want to let a commercial pest management company perform this task, since they'll have the proper protective equipment. Some companies may also be able to vacuum out the insects, but don't try this yourself.

Sprays. The same sprays used on yellow jackets are usually labeled for other types of wasps, too.

Preventing Stings
Don't swat at flying insects. If they land on you, gently brush them off, then walk away. Here are other precautions you can take:

-- Don't drink out of soda cans; bees and wasps may be lurking inside. Pour the drink into a glass so you can see it.

-- Observe the flight pattern of insects to determine their nest site, then avoid it.

-- Keep garbage cans and pet food covered.

-- Avoid floral perfumes, lotions, and hair products; these attract bees.

-- Tuck pant legs into socks to prevent insects from flying or crawling up.

If You Get Stung
Walk quickly away from the area. If you're stung by a honeybee, you may be near the nest. If you're stung by a yellow jacket, the insect may leave behind a chemical that marks you as the enemy, inciting other yellow jackets to attack.

Honeybees leave their barbed stinger in your skin; remove it by scraping the sting site with your fingernail or something stiff, like a credit card. Don't pinch it to pull it out or you'll just inject more venom. Other bees and wasps don't leave their stingers behind so this step isn't necessary.

There are commercial sting remedies available, but many people swear by homemade concoctions. Apply any of the following to the sting site:

-- a paste of baking soda and water
-- a meat tenderizer containing papain, such as Adolf's
-- a poultice made by chewing a piece of plantain (a common weed) into a pulp
-- the cut side of an onion
-- Preparation H
--ice

Aspirin and ibuprofen can reduce swelling and ease the pain. Antihistamines and cortisone cream may reduce swelling and itching.

Warning signs of a bee or wasp sting allergy include symptoms such as a dry cough; red, itchy eyes; wheezing; hives; sudden anxiety; weakness; tightness in the chest. Seek medical help immediately! Anyone suspecting they are allergic should carry a bee sting kit, such as an epi-pen.

Don't react to the presence of flying insects by reaching for a can of insecticide. Take the time to understand what you're dealing with, what type of threat it poses, and if control is warranted. Remember that most insects found in the landscape are beneficial or benign. Bees are most definitely beneficial, and wasps are, as well, when they don't pose a direct hazard.