Eastern Yellowjacket

Seasonal diet shift explains late-summer aggression. Early summer: Protein (caterpillars, flies, carrion) to feed growing larvae—workers are beneficial predators during this phase. Late summer/fall: As natural food sources decline and larvae mature, adults switch to sugars (fruit, soda, garbage)—this triggers the aggressive scavenging behaviour at picnics and trash cans.

Paper nests in underground cavities (old rodent burrows), wall voids, or attics. Single entrance hole.

Active May-October. Most aggressive August-September when colony peaks and natural food declines.

Wasps entering ground hole: Steady traffic of wasps flying in and out of a small ground opening. Increased wasp activity near food: Yellowjackets persistently visiting outdoor meals, garbage, or fallen fruit. Wasps in wall or attic: Buzzing in walls, wasps emerging indoors suggest hidden nest. Paper nest visible: Grey papery structure in protected location (rare to see underground nests). Wet spots on drywall: Moisture stains or soft spots on interior walls may indicate wasps chewing through from a nest inside the wall cavity—they will find alternate routes if blocked.

Keep food and drinks covered outdoors. Seal garbage containers tightly. Fill rodent burrows that could become nest sites. Seal gaps in siding, soffits, and foundation. Avoid wearing bright colours or floral scents outdoors.

Dust or aerosol treatment applied directly to nest entrance at dusk. Do NOT seal entrance before treatment—trapped wasps will find alternate routes, often indoors.