In late summer and early fall, yellowjackets (Vespula and Dolichovespula spp.) can be particularly pesky. But to explain why they can be a particular pain (sting pun intended) during this time of year, some yellowjacket background is needed.
Yellowjackets typically build paper nests in underground cavities, but can also nest in shrubs, trees, attics, and buildings. In the late summer, these colonies peak in size, and contain thousands of individual wasps.
Yellowjackets, similar to their honey bee cousins, are social. They have a reproductive caste (queen and males) and a worker caste (non-reproductive females). Yellowjacket colony life cycle begins in the spring when a mated queen establishes a new nest. She builds paper cells (similar to honey bee comb) where the laid eggs (all female) will develop into larvae and then adult wasps. The new female adults (workers) will then forage for food to feed their young sisters.
So early in the year, yellowjacket workers are very busy building up the colony by feeding the young. Unlike their bee cousins, yellowjackets are predators and get their protein mainly from eating other insects. They can therefore play a vital role in keeping crop and garden pests in check.
However, late in the summer, these busy workers begin to stray from their main duties, and can become significant pests to us. As the summer starts to wind down, yellowjacket colonies focus on producing reproductives, new queens and males, instead of new workers. The new reproductives will leave the colony, mate, overwinter, and then start a new colony in the spring. Unfortunately for the old queen and workers, they aren’t built to make it through the long cold winter, and will eventually die (except for in warmer climates where nests can sometimes be perennial). So it’s during this time, after reproductives are produced, that the workers begin to go a bit rogue, as their services, feeding their sisters, are no longer needed.
As the colony dwindles down, workers are left to their own devices to gather food for themselves. They are incredibly flexible eaters, and will enjoy your hamburger, hot dog, or lunch meats just as much as you! They start searching out sugars more as well for a quick burst of energy, so that soda you’re drinking starts to look mighty tempting to a yellowjacket.
So while yellowjackets can get a bit too close for comfort during this time of year, remember that this might be their last meal, and try to have a bit of compassion. Or if you really can’t stand them, take comfort that they aren’t long for this world.