Aug. 17--We were bothered by yellow jackets while eating on our deck over the weekend. Is there anything that I can do to eliminate this problem? I have a large garden with lots of different plants.
--Thomas Murray, Kenilworth
Populations of yellow jackets -- a kind of wasp -- build up in summer. They are unwelcome visitors to picnics.
Yellow jackets are particularly attracted to sweet foods like soda. A wasp may crawl into your soda can in between sips if you do not pay attention.
Once these social insects find a good food source, they will continue to return to the site, so the best way to reduce this pest problem is to avoid attracting them in the first place. Practice good sanitation when you dine outdoors: Thoroughly clean up all food and drink residue when you are finished eating and dispose of it in a covered trash can.
There are traps sold for yellow jackets. However, since the traps use a pheromone to lure the insects, the result may be to attract even more of them to your eating area. You will get the best results by keeping the area clean.
Be alert for yellow jackets when working in the garden in late summer. They tend to nest in the ground or in stone walls, and they will sting to defend a nest if you happen to disturb it by digging, pruning ground covers, or weeding.
You may be able to spot a nest if you see a concentration of yellow jacket activity in one place. When the weather is warm and sunny, there will be a lot of yellow jackets flying in and out of a nest.
There is no need to treat the nest unless it is in an area where it poses a safety threat to people. Simply avoid the nest as you work in the garden.
Bald-faced hornets, another kind of wasp, construct large paper nests in trees and large shrubs at head height and above. You will be most likely to disturb a hornets' nest by pruning a tree or bumping into a nest with a piece of equipment.
Paper wasps will build nests under eaves, signs, benches and fence railings and will sting if disturbed. These are beneficial insects that help control pests, so control them only if they pose a safety hazard.
Johnson is senior director of horticulture for the Chicago Botanic Garden in Glencoe; ctc-realestate@tribune.com.
