14 August 2011

Digger Wasps are not dangerous to humans and how to get rid of them

Image from Tom Murray's database online. Go to his site to see photos of wasps that may be apperaing in your garden.
Before you buy boxes, bags and bottles of insect spray, learn more about digger wasps making nests in your yard.


"In most situations it is best not to eliminate ground-nesting bees and wasps since they are valuable in agricultural production by either pollinating many different plants or serving as useful predators in controlling harmful pests. However, when nests are located in areas such as yards, gardens, flower beds or playgrounds, control may be justified to prevent the chance of being stung."

Great Golden Digger Wasp from Bug Guide dot net - another great identification site.


Digger or Threadwaisted Wasps
A digger wasp.
A digger wasp.
Both the blue digger and golden digger wasp are beneficial, appearing in the morning and flying over the lawn all day, then leaving in early evening. Digger wasps are solitary wasps with each female working alone to produce her offspring instead of having the help of several workers as in social chambers or cells. These chambers are provisioned with food for the offspring. After the eggs are laid in or on the "provision," the offspring are on their own to live and grow to adults that emerge the following summer.

The blue digger about 3/4-inch long is shiny metallic blue on both the wings and body. This slender wasp provisions its nests with grasshoppers and crickets. Also, the inch-long golden digger wasp with shiny gold markings on the face and abdomen uses grasshoppers and crickets as stored food for their offspring. Often, wasps can be seen flying about a foot or less above the ground. Others may be perched on shrubs and trees.

Due to their large size, they are assumed to be extremely dangerous. Actually, they are not aggressive but curious and investigate persons and pets near their burrows. Stings are quite rare. One can walk safely through them as they hover over the lawn.

Control

If ground-nesting bees and wasps can be ignored and their tunnels tolerated, do so since they are valuable in agricultural production and helpful by controlling pests in nature. If nests are in locations undesirable and stinging is a great possibility, control is justified. During the day, carefully watch where the nest entrances are located. After dark, tunnels and the surrounding area can be treated with dusts of carbaryl (Sevin), bendiocarb (Ficam D) or diazinon when the nest is in the ground. Use pyrethrins, permethrin, resmethrin or propoxur (Baygon) when the nest is in the side of a building. Other lawn and garden insecticide sprays can also be used, but dusts have the advantage of not soaking into the soil. Those who are allergic to bee stings, should contact a licensed, professional pest control operator to perform the control job. Always read the label and follow directions and safety precautions.
Cicada Killer Wasp from Iowa State Univsersity Plant and Insect Diagnostic Clinic
From Iowa State Univ.
"At least 3 different species of wasps construct nests in the ground in Iowa. These "digger wasps" include the cicada killer wasp, the largest wasp found in Iowa. Cicada killer wasps may be up to 2 inches long. They are black with yellow markings on the thorax and abdomen and they have rusty colored wings. The great golden digger wasp is slightly smaller. The abdomen is reddish-orange except at the tip which is black. A third species is 1 inch long and completely black with iridescent blue wings."

and

"Wasps are generally beneficial and a nest in an out of the way location where it is not likely to be disturbed should be left alone. If, however, a nest is located where problems could arise, such as under a deck or near an often used door, removal is justified. Ground nests of cicada killers and other digger wasps can be destroyed by placing an outdoor use insecticide dust containing carbaryl in and around the nest entrance during the night. The dust particles will adhere to the wasps as they come and go from the nest. Cover the nest opening with a shovelful of soil after all activity has stopped."

Click on this link to see one really close up at North American Insects and Spiders - another great site to know about.

So, try to keep your cool and let these harmless but scary looking neighbors live in your garden.

3 comments:

Negi said...

Thanks for great information you write it very clean. I am very lucky to get this tips from you


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Anonymous said...

Not dangerous?? I was stung four times today mowing the grass.

Martha Stoodley said...

RE stings - Anonymous
Wow that's a bummer.
They will sting if they are disturbed and annoyed.

Do you walk behind a mower? We have 3 acres so we always have a good distance on the riding mower.