Wasps are beneficial insects, even the ones that occasionally sting. They are busy parasitizing or otherwise preying on pesky houseflies or soft-bodied insects like caterpillars, some of which may be munching away in your garden. They are easily recognized: they have two translucent pairs of wings, are hairless (unlike bees), black and yellow or black and white, and 12 to 25 mm long depending on caste or type (queen, worker or drone). Of the several species found in the prairies, it is the paper wasps, hornets and yellowjackets (the ones that I call nuisance wasps) that you need to watch out for.
As a social insect, they live in colonies ranging from less than a hundred to as many as 5,000. You are probably most familiar with the large grey roundish papery hornet nest, suspended in trees, under eaves or from some other sturdy support. But other types of wasps like yellowjackets live underground or in an enclosed location. And yet others build open nests, not enclosed in paper.
It is usually this time of year when they're a nuisance, as their numbers are peaking and as they are foraging for food. Barbecued meats (protein source) and sugary drinks are sure to attract, as will soft fruits in the garden like strawberries and raspberries. I know it's hard to do, but avoid swatting at wasps. A squashed wasp releases a scent that will bring their sisters on the scene looking for a fight. They will also defend their nests vigorously if you approach too closely or if they feel threatened.
My first wasp sting, only a few years ago, was from a yellowjacket as I blithely sat next to a rock wall sipping a cool drink. It felt like an electric jolt, partly because of the venom itself but also because the yellowjacket, like the paper wasp and hornet, can sting repeatedly. Fortunately, I suffered only temporary pain plus a small but permanent scar as a reminder. Others may react more dramatically - at worst, suffering a severe allergic shock.
Control starts as soon as you spot a developing nest around your home and garden. Underground nests are more of a challenge to spot - watch for sudden appearance of wasps coming from the ground. The entrance is likely surrounded by a small pile of loose soil. There are wasp control products sold in spray cans capable of shooting great distances. Wait until dusk when the wasps will have retired for the evening. Stand as far back as practical and be prepared to make a quick retreat. Aim for the opening and give the nest a good dose. If it is a very large nest, you may have to repeat. If it is a suspended nest, enclose it in a plastic bag (after all activity has ceased) and tie it tightly at the top to prevent any survivors from escaping. Place in freezer overnight to completely kill the colony before disposing in garbage.
Imitation wasp nests are reported to deter wasps from establishing a colony nearby. Wasps are territorial animals and won't encroach into another colony's territory.
If you can't find a nest, but are still bothered by wasps, you can hang up a wasp trap to reduce their numbers. These are available from garden centres. Or a simple one you can make yourself starts with a one or two liter plastic pop bottle. Cut the top off an inch below the shoulder. Invert the top and insert it into the bottle (remember to remove the lid), lining up the cut surfaces. Take a hole punch and make a couple of holes through both the top and bottom portion on opposite sides of the bottle. Thread a cord through the holes to allow you to hang your trap. Next bait your trap. If hanging up in the spring, use a small piece of raw meat (protein source; not chicken) with a little bit of water - you might even trap a queen this way. If trapping later in the season, half-fill the base with a sweet liquid (sugar and water, juice, stale pop, etc.) plus a squirt of liquid dish soap. Once a wasp enters the trap, they have a difficult time figuring out how to exit. Remember to empty the trap regularly - be wary of live wasps. Bury or flush the dead wasps to avoid attracting their angry vengeful sisters. One final tip: place the trap away from where you, your children or pets spend time.
- This column is provided by the Saskatchewan Perennial Society
