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Summertime Stingers
Managing wasps, hornets at home


NO IDAHO SUMMER IS COMPLETE without an al fresco meal. And perhaps no such meal seems complete without inevitable yellowjackets or other stinging insects buzzing your face and arms and dive-bombing your entrées and drinks.

Why do they come, and are there ways to discourage such guests?

Answers are in a new trio of publications by University of Idaho entomologists who tackle everything you want to know about stinging insects living in and around Idaho homes.

While the purpose of the three 8- to 16-page color-illustrated bulletins is to help homeowners consider a variety of ways they can manage these insects, publications also offer a valuable guide to nesting habits and lifestyles of bees, hornets, wasps, yellowjackets, flying ants, mud daubers, and other common Idaho stinging insects.

Each provides fascinating close-to-home natural science information to help adults and youth alike better understand our world. For example, when did German yellowjackets—more aggressive than our native yellowjackets—immigrate to Idaho? (During the 1980s.) And why are Africanized “killer” bees unlikely to get a year- round foothold in Idaho? (Our winters are too cold for their survival.)

“Most of these insects should be left alone because they are beneficial,” says lead author Ed Bechinski, University of Idaho entomology professor and coordinator of pest management for UI Extension. “They play important roles in controlling other insect populations like aphids, caterpillars, and grubs. And many of them serve the important role of pollinating plants,” adds Bechinski. Control is needed mainly when nests are too close to places where humans hang out.

Other authors include Frank Merickel, manager of the UI CALS Barr Entomological Museum; graduate research assistant Lyndsie Stoltman; and Hugh Homan, UI professor emeritus of entomology.

Strategies to protect late summer picnics

Yellowjackets may be the worst offenders annoying out-of-doors dining.

That’s because by late summer their natural living prey are gone, forcing these sleek hairless yellow-and-black insects to compete with you for your sweet drinks and protein.

  1. YELLOWJACKET TRAPS. Place 6 to 12 yellowjacket traps at intervals at least 20 feet from your proposed dining or gathering spot. (Such traps placed too close to the gathering area become yellowjacket invitations to your party.)

    Do not swat at flying stinging insects; some will release air-borne chemicals—called alarm pheromones—that could stimulate a stinging attack from other workers. If a wasp lands on you, flick it away with your finger. Never crush the bodies of workers, especially near the nest; crushing also releases alarm pheromones that induce a mass attack. __

  3. MINIMIZE USE OF PERFUMES, colognes, soaps, or other scented body lotions when yellowjackets, bald-faced hornets, and paper wasps can be expected; these scents can be highly attractive to foraging wasps.

  4. WEAR WHITE OR TAN CLOTHES rather than light blues or bright pinks, reds, and oranges; close-fit- ting shirts and pants are better than loose-fitting clothes because wasps are less likely to become accidentally trapped against the skin.

  5. COMMERCIAL MOSQUITO/TICK REPELLANTS DON’T WORK against stinging insects. Indeed, it is possible that the scents of some products attract yellowjackets and other wasps.

  6. COVER SERVING DISHES at outdoor picnics; clean up spilled drinks and food scraps; clear away dirty plates.

  7. DO NOT LEAVE SOFT DRINK CANS OR BEER BOTTLES OPENED and unattended; yellowjackets can crawl unseen into open containers and sting painfully around the mouth.

  8. KEEP LIDS ON TRASH CANS and dumpsters; clean to remove attractive odors or use disposable can liners; rinse cans and bottles before placing in outdoor recycling bins.

  9. MOVE FOOD GARBAGE AWAY from patios or places where people congregate.

  10. PET FOOD. Don’t leave moist pet foods outside.

  11. APHID CONTROL. Control infestations of aphids and scale insects that produce honeydew on landscape trees and shrubs. They attract some stinging insects.

  12. ELIMINATE DRIPS FROM FAUCETS, sprinklers, and garden hoses, especially during the dry parts of the summer. Puddled water attracts workers.

  13. CLEAN UP ROTTING APPLES and peaches that fall from trees; pick cane berries before they over-ripen.

  14. REPLACE LATE-FLOWERING landscape plants around decks and patios with non-flowering ornamentals.
LARGE PAPERY NESTS built by aerial yellowjackets and bald-faced hornets in landscape trees and shrubs—visually interesting and by fall often as large as a soccer ball— can be brought into homes safely during late fall.

Authors suggest that on cool November days you clip abandoned nests from branches, then bag and place in the freezer for one or two days. “Freezing kills any remaining workers or other insects—like earwigs—that sometimes live in old nests. Physically shake any dead insects and other debris from the nest; otherwise nests can become an odor problem,” says the yellowjacket publication. “Papery nests are delicate and disintegrate quickly under harsh winter weather.”

Order or download. The University of Idaho’s new stinging insect publications include:
  • BUL 852 Homeowner Guide to Yellowjackets, Bald-faced Hornets, and Paper Wasps, 16 pages, $4.

  • BUL 853 Homeowner Guide to Minor Stinging Insects, 8 pages, $3.

  • BUL 854 Homeowner Guide to Bees, 12 pages, $4.
Order them from the University of Idaho College of Agricultural and Life Sciences Publications Warehouse at 208.885.7982, or e-mail

Free online. You can download them for free at Select "insect pollinators".