Early fall brings pleasant temperatures to the end of summer, making barbecues and al fresco dining more comfortable than peak summer. Unfortunately, you may have also noticed that it also invites wasps to the party.
If it feels like wasps are suddenly everywhere — and are way more aggressive and invasive than usual — you aren’t imagining things. Biological shifts inside the nest make late-summer and early fall wasps noticeably more defensive and persistent around humans.
Here’s why, and who to call for help.
Why you’re seeing more aggressive wasp behavior
Wasp aggression in late summer boils down to three main factors: peak colony size, shifting dietary needs and dwindling natural food supplies.
Dr. Jim Fredericks, board-certified entomologist and senior vice president of public affairs at the National Pest Management Association (NPMA) says: “Late summer and early fall are when encounters with yellow jackets, wasps and hornets tend to be at their highest because colonies are at their peak size. A colony that began with one queen in the spring may contain hundreds or, sometimes, thousands of workers by the end of summer.”
While wasps tend to focus on protein-based foods during the earlier summer, such as other insects, there are additional changes at the end of the season. “When reproduction slows, adult yellow jackets and other wasps feed on high-calorie sugary substances to fuel the energy needs of their colony,” says Fredericks. “Since our outdoor gatherings usually involve food, and often a lot of sweet food, interactions between humans and stinging insects hit a high around now because they want what we have readily available.”
Which wasps become the biggest nuisance?
“Wasps” is an overarching term for a variety of species, including paper wasps, yellow jackets and hornets. While you may have encountered many species, yellow jackets tend to be the most aggressive in late summer. In fact, they tend to be the most aggressive, period.
Yellow jackets are aggressive scavengers by nature. They’re most likely the ones buzzing around you when you’re eating at the barbecue. In late summer and early fall, they’re especially craving carbohydrates and sugars, so they tend to be even more aggressive. Because their colonies can grow to include thousands of individuals, their sheer numbers make them a constant presence around human activity.Paper wasps and hornets also reach peak numbers during this window, but they’re generally less interested in your plate and more focused on defending their aerial nests.
Signs wasps are entering their peak season
Knowing what to look for can help you spot wasp activity before it turns into a painful encounter:
- More wasps around outdoor meals: Uncovered meats, sodas, fruit salads and beer attract starving workers seeking protein and sugar.
- Increased activity near trash cans: Open garbage bins and recycling cans are often feeding frenzies for wasps, especially at peak season.
- Heavy traffic in and out of nests: A steady line of insects entering a hole in the ground or under a roof eave signals a mature colony.
- More wasps around ripe fruit trees and gardens: Fallen, fermenting fruit is a prime late-season sugar source for foraging adults.
Weather can make wasps seem more aggressive
While the hunt for sugary food is a prime motivator, the hot, dry weather of August and September can also fuel wasp aggression. “Temperature, rainfall, drought, food availability, species and geography all help determine when stinging insects emerge, how quickly colonies develop and how long workers remain active,” Fredericks notes.Droughts can dry up nectar sources, which can drive wasps away from normal foraging grounds and onto patios and parks. Likewise, says Fredericks, “The warm fall weather can give stinging insects additional time to forage before sustained cold temperatures bring the colony’s seasonal cycle to an end.”
What should you do if wasps are everywhere?
Swatting at wasps is a bad idea, and simply running from them gets tiring. There are some better precautions you can take to avoid them in the first place. These include:
- Keeping outdoor food covered: Use mesh food tents or sealed containers during outdoor meals.
- Sealing garbage and recycling: Ensure outdoor bins have tight-fitting lids, and rinse beverage cans before tossing them in the recycling.
- Cleaning up fallen fruit: Pick up dropped fruit from nearby trees before it can begin to rot.
- Rinsing food and drink residue from containers before tossing them: The residue can attract pests to your trash and recycling bins.
- Bring kids and pets inside: Keep anyone who may be prone to wandering near a nest indoors or far away from the nest.
- Avoiding strong perfumes or other heavy fragrances outdoors: The strong scents may attract pests.
- Sealing cracks and repairing windows and door screens: Any exterior cracks on your home could make attractive homes for yellow jackets
- Hiring help for high-risk nests: If yellow jackets set up a nest near an entry door or underground in a high-traffic lawn area, call pest control. Fredericks says, “A professional can identify the species, locate the nest and build a plan based on the specific situation.”
To reiterate, swatting a wasp is a bad idea. You might crush it, but that will release an alarm pheromone that signals nearby nestmates to attack. Just take precautions to avoid attracting them, and walk away when you’re confronted.
Frequently asked questions
What month are wasps most aggressive?
August and September are typically the peak months for wasp aggression. By this time, nests have reached maximum size, and natural food supplies begin to decline rapidly.
Are wasps more aggressive before they die off?
Yes. As the temperature drops and food vanishes, worker wasps become desperate for calories. This is a main reason why they’re so aggressive before cold weather sets in.
Why are yellow jackets so bad in late summer?
Yellow jackets build massive colonies containing thousands of workers by late summer. Between the sheer size of their colonies and the desperation to find food before the winter, wasps become a lot more common at outdoor gatherings with food.
Does hot weather make wasps angrier?
Higher temperatures speed up insect activity and dry up natural water and nectar sources. Both factors force wasps to forage more aggressively.
Are wasps more aggressive than bees?
Generally, yes. Not only will they initiate human contact more than bees will, but they’re also natural scavengers who will aggressively hunt food, even if it’s in your hand.
When will wasp season end?
Wasp season usually ends with the first hard freeze. Freezing temperatures kill off the worker wasps and males, while newly fertilized queens hibernate underground or under tree bark until spring.