Whether they are competing for your barbecued burger or just buzzing around, making you and your kids nervous, yellowjackets can be a real headache.

Napa County hosts at least a dozen different types, but the ones refered to as common yellowjackets are the ones we see most often.

Yellowjackets are a type of social wasp. They are scavengers and predators and very protective of their nests. Workers usually stay within 400 feet of home. They make their nests along fence lines, ditches or paths and live in colonies in locations as diverse as rodent burrows, attics, walls of homes, tree cavities or holes in the ground.

If you have ever looked inside a yellowjacket nest, you probably noticed suspended combs that look like they are made of paper. To build this series of combs, yellowjackets depend on fibers from trees or your house, using this chewed pulp to construct their homes.

When yellowjackets emerge from their nest for the first time, they conduct an orientation flight to scope out their new world.

If you disturb a nest in the ground or grab the wrong rock when you are climbing, you can find yourself in a precarious situation.  Although only 1 in 1,000 people are allergic to wasp and bee stings, incurring the wrath of a disturbed nest can leave anyone battered.

Yellowjackets are not like honeybees, which can sting only once because their stinger remains embedded in the victim. Yellowjackets can sting multiple times. When they are alarmed, stinging or injured, they release a chemical signal called a pheromone that brings other yellowjackets to their aid. And then the new brigade stings the interloper, too.

Yellowjackets pack a lot into their 30-day lifespan. A queen starts her nest by digging an opening in the ground or finding a suitable space in your garage eaves or walls. She lays just a few dozen eggs and rears this first batch as the future egg producers for the colony.  The next hatchlings are workers whose job is to bring back meat, fish, flies, caterpillars, and other protein-rich foods for the young. They are the ones who raid your picnic tables, box lunches and barbecues. These picnic pirates tear the food into pieces and chew it up before feeding it to the larvae, who, in turn, excrete a honeydew to feed the adults. 

If you have noticed that some yellowjackets go after meat and some prefer sweet stuff, you are right. While the adults scavenge proteins for the young, their own preference is for sugar and starch. Nothing in your picnic basket is safe.

To keep yellowjackets away from your home, mark your calender to put up pheromone traps in March. That’s when the queens are usually coming out to find a secure place for a nest. When you trap the queen, you eliminate a lot of future trouble.

To avoid getting stung by yellowjackets, never swat them. They will rarely sting if left alone. Yellowjackets are attracted to perfume, scented sunscreen, cosmetics and brightly colored clothing, so keep that in mind as you dress for summer events. 

Don't go barefoot, especially across dirt or vegetation. Keep outdoor food covered and your drinks and bottles closed. Always look in an open soda can before drinking if yellowjackets are around. Keep garbage cans tightly closed and a good distance from family areas.

If you or your children get stung, wash the sting with soap and water, and apply antihistamine or an anti-itch medication. An ice pack can help reduce swelling and pain.  If you see any sign of an allergic reaction, get medical help quickly, especially if the victim has difficulty breathing or swallowing or was stung in the throat or mouth.

If you are attacked by yellowjackets, leave the area quickly. They are almost always protecting their nest and will continue to sting until the threat (you!) is gone. Since their domain is about a 400-foot radius, don't stop until you know they have abandoned the chase. 

All this information on yellowjackets comes from Napa County Mosquito Abatement (http://www.napamosquito.org). If you find a yellowjacket nest, call them at 553-9610. They will remove it for you, because it can be a dangerous task.

Napa County Master Gardeners (http://cenapa.ucdavis.edu) are available to answer gardening questions Monday, Wednesday and Friday, 9 a.m. to noon at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 253-4221, or 877-279-3065.