As the warmer months progress, swarming insects become a common sight in the Midwest, especially in Wisconsin. While some insects, like honey bees, are vital pollinators and generally non-aggressive, others, such as wasps, yellow jackets, hornets, and ground bees, can be more defensive, especially in late summer and fall. Understanding the differences between these insects can help you enjoy your outdoor spaces safely while protecting the beneficial pollinators we rely on.
Unlike honey bees, more aggressive insects like wasps, hornets, yellow jackets, and ground bees tend to swarm when they feel their nest is threatened. Here are some key reasons why they swarm:
Defending Their Nest: Territorial behavior is common among wasps, hornets, and yellow jackets. When they feel their nest is at risk, they will aggressively swarm to protect it.
Late Summer and Fall Behavior: As the seasons change, food sources dwindle. This is when wasps and yellow jackets become particularly aggressive, scavenging for sugary substances, meats, and proteins, which often leads to more human encounters.
Disturbance: Accidentally disturbing a nest, particularly of ground bees or yellow jackets, can trigger a defensive swarm. These insects use pheromones to signal others in their colony to join the defense, making them especially dangerous.
Foraging for Food: Wasps, yellow jackets, and hornets are omnivores, meaning they will swarm near food sources like sugary drinks, trash, and even fallen fruit in your yard.
How to Tell the Difference Between Bees and Aggressive Pollinators
Here’s a quick guide to help you distinguish between the less aggressive pollinators like honey bees and their more aggressive counterparts.
Honey Bees
Appearance: Golden-brown with dark stripes and covered in fuzz.
Behavior: Generally docile, honey bees only sting when threatened, and they die after stinging. They are focused on collecting pollen and nectar.
Swarming: Honey bee swarms are non-aggressive and happen when they are searching for a new home.
Yellow Jackets
Appearance: Bright yellow and black markings, smooth-bodied, and smaller than honey bees.
Behavior: Extremely aggressive in late summer and fall. Yellow jackets sting multiple times and are often found near trash or picnic areas scavenging for food.
Swarming: Yellow jackets swarm to defend their nest, and their stings release pheromones that attract more of them to join the attack.
Wasps
Appearance: Long, slender, and smooth-bodied, often black and yellow.
Behavior: Wasps can become aggressive if their nest is disturbed. They sting multiple times and are drawn to food sources.
Swarming: Wasps swarm when their nest is threatened or when foraging for food.
Hornets
Appearance: Larger than yellow jackets, with black and white or yellow markings.
Behavior: Extremely territorial and aggressive. Hornets will defend their nests vigorously and sting multiple times without dying.
Swarming: They will swarm in defense of their nest, and their sting is especially painful.
Ground Bees
Appearance: Similar in size to honey bees, but they build nests in sandy or loose soil.
Behavior: Less aggressive than wasps or hornets but will sting if their nest is disturbed.
Swarming: Ground bees swarm near their nest when threatened but are generally less aggressive than other stinging insects.
Key Differences:
Diet: Honey bees are herbivores and only collect nectar and pollen, while wasps, yellow jackets, and hornets are omnivores, feeding on proteins and sugars.
Sting Frequency: Wasps, yellow jackets, and hornets can sting multiple times, while honey bees can only sting once before dying.
Aggression: Wasps, yellow jackets, and hornets are much more aggressive than honey bees, particularly in late summer and fall.
What to Do If You Encounter Aggressive Pollinators
Stay Calm: Quick movements can provoke an attack, so slowly move away from the area.
Avoid Scents and Bright Colors: Perfumes and bright colors can attract aggressive insects.
Remove Food Sources: Keep food and drinks covered, especially when eating outside, and clean up spills quickly.
Secure Trash Bins: Make sure trash bins are tightly sealed to prevent yellow jackets and wasps from scavenging.
What About Honey Bee Swarms?
If you see a honey bee swarm, there’s no need to panic. Honey bees are typically docile during this time as they search for a new hive location. The swarm is not aggressive, and local beekeepers can safely remove it and relocate the bees to a proper hive where they can continue pollinating and producing honey. In Wisconsin, there are many resources, including beekeeping associations and local extension offices, that can help. (See links below)
Ground Bees: A Special Case
Ground bees are one of the most common concerns for homeowners. They often nest in sandy or loose soil and are generally less aggressive than wasps or hornets. Ground bees are solitary, meaning they don’t build large colonies, but they do swarm around their nests when disturbed. If you notice ground bees in your yard, they are unlikely to pose a significant threat unless you disturb their nesting area.
Invasive Species Concerns
While honey bees are essential pollinators, some wasps, hornets, and yellow jackets are considered invasive species, such as the European hornet or certain non-native yellow jacket species. These invasive insects can disrupt local ecosystems and are more aggressive than native pollinators. Always check with a professional before attempting to remove or control invasive species.
Swarming and Aggressive Pollinators: What to Look For
Insects like yellow jackets and hornets may swarm when their food sources become scarce or their nest is disturbed. Swarming behavior in these insects tends to be more aggressive than honey bee swarms. If you notice a swarm of aggressive pollinators:
Identify the insect: Was it provoked by a food source or a nearby nest?
Call a professional: Always contact a pest control expert if you suspect an aggressive insect nest nearby. Swarms of wasps, hornets, or yellow jackets can be dangerous to handle on your own.
Know Your Pollinators
Recognizing the difference between helpful pollinators like honey bees and aggressive insects such as wasps or yellow jackets helps you maintain a safe outdoor environment. Honey bees are vital to the ecosystem, and their swarms are generally harmless. On the other hand, wasps, yellow jackets, and hornets can become a nuisance, particularly in late summer and fall, so it's crucial to deal with them cautiously.
At Be Green Pro, we prioritize eco-friendly, pollinator-safe practices. We’re always here to provide helpful advice or to connect you with trusted professionals for safe insect removal when needed. Together, we can protect pollinators and keep your outdoor spaces safe.
Link for The Milwaukee Waukesha Beekeepers Association where you can learn more about the application and instructions for becoming a beekeeper and what to do if you find a bee swarm.
