Why are wasps suddenly crashing your picnic?

Image by Jim Williams

Wings, potato salad, corn hole and cool beverages, all staples of late summer barbecues and tailgate parties.   A great time until the wasps arrive, dive bombing the watermelon and hiding in your soda can.  They can be annoying, their stings are painful, and it’s downright scary if you are allergic.

Why do they seem to harass us so much in August and September?  To figure this out we need to learn a little more about wasps, their life cycle and habits.   There are many different types of wasps, most don’t sting and are very beneficial.

Unlike bees which have fuzzy bodies, wasps have thinner, elongated bodies.  Bees collect pollen and are critical to our food supply as they are excellent pollinators.  Wasps are insect predators, eating caterpillars, beetles, flies, spiders, and other bugs to feed their larvae.

Most wasp species are solitary and do not sting.   The mud dauber for example builds mud tubes and pack the tubes with spiders.   Solitary wasps are extremely helpful to farmers protecting their crops from damaging pests.  Social wasps include paper wasps, hornets, and yellow jackets.

These wasps construct their nests from wood fibers which they chew into pulp, mix with their saliva, and mold into paper.  Paper wasp nests are open, umbrella shaped nests which they hang off eaves, under tables, or other horizontal structures.   Hornets construct large closed nests which often hang from trees.   Yellow jackets construct their paper nests underground, usually in holes made by rodents or moles.

All of these social wasps can sting repeatedly to defend their nest or if they feel threatened.  Their sting is much more painful than a bee sting. Swatting or killing a wasp will cause it to release a danger pheromone which will signal other wasps to attack.

A new colony is formed each spring.   Only the mated queen survives the winter tucked away in a sheltered place.   She emerges in spring and lays eggs in a new, small nest.  From these eggs a first generation of workers will grow to enlarge the nest.  The queen keeps laying eggs all season, while the workers bring back insects to feed the hatching larvae.   They are so busy working that they don’t have time to feed themselves.

As the queen lays her last brood of eggs in late summer the workers have little left to do.  They go in search of sugary foods that will give them a boost of energy.   Feasting on fermenting apples fallen on the ground or sweet barbecue sauce at the tailgate, it is their end of season party before they succumb to the freezing frost.

If the wasp nest is in an area you can avoid, it is best to leave it alone.  Be aware that hornet nests may release hundreds of wasps when disturbed.    Setting out traps may just lure them to your yard, they can travel over 1/4 mile to find food.    When they become a pest at your picnic, try wafting them away rather than swatting at them.  If all else fails put, the food away or go inside.  When frost arrives they will disappear.

Julie Borgmann

Julie Borgmann

Education and Development Director
Julie Borgmann is the Education and Development Director for Red-tail Land Conservancy. Her passion is connecting people to nature for conservation and wellbeing.