How do I tell a paper wasp nest from a yellowjacket nest?
Look at the nest, not the insect. wasps in flight all look alike and nobody should be squinting at stripes from three feet away. An open comb of hexagonal cells on a short stalk, with wasps sitting on the exposed face, is a paper wasp nest. There is no paper covering. These hang under eaves, deck rails, porch ceilings, and grill lids, and the colony defends only the immediate area around the comb. A nest you cannot see, with wasps pouring in and out of a single hole in the lawn, a foundation gap, or a soffit seam, is a yellowjacket colony. The paper is all inside the cavity, so the entrance tells you nothing about the size. A large gray football hanging in a tree or from a high eave, fully enclosed, is a bald-faced hornet nest. It is an aerial yellowjacket and it defends the whole nest aggressively. The first is often a homeowner job. The second and third are not, and getting the identification right before you touch anything is most of the safety here.
The wasp year on the Front Range, month by month
March is the surprise. Colorado State University notes European paper wasp activity is sometimes seen in the first half of March, earlier than most people expect at this altitude. A single overwintered queen picks a site and starts a few cells alone. She cannot defend anything, and this is the cheapest moment in the whole year to intervene. April and May are foundation months. Western yellowjacket queens are choosing burrows and voids, and the first workers hatch and take over building. A nest that is still the size of a golf ball in May will be a serious job by Labor Day. June and July are growth. Colonies feed on insect protein, which keeps them out of your business, so a nest can sit undetected in a wall for weeks. August through October is the peak in Aurora and the reason this page exists. Colonies are at maximum size, foragers scavenge human food, and defensiveness is highest. November ends it. Freezing nights kill workers, mated queens tuck into bark and wall gaps, and the nest goes empty for good.
Where wasps get into Aurora houses
wasps do not chew openings into a building. They find gaps that already exist, which is useful, because gaps can be inventoried and closed. Up high, the usual entries are soffit returns where a roofline meets a wall, unscreened gable and attic vents, gaps at the top of siding runs, and voids behind fascia. Any of those leads to a dry, protected cavity, and dry is the operative word in a place that averages 15 inches of rain. At ground level, the entrances are abandoned rodent burrows tight against the foundation, gaps under concrete steps, and the hollow under a deck. Western yellowjackets adopt an existing cavity rather than excavating a new one. The European paper wasp adds a category of its own. Colorado State University lists outdoor grills, large bells, pipes, rock cavities, and hollow spaces behind walls among its nest sites, which on a typical Aurora lot means fence post tops, patio umbrella poles, and playset tubing. Stand back on a sunny morning and follow the flight lines. Traffic converges on the real entrance and it becomes obvious once you stop searching and start watching.
When is a sting a medical emergency?
Most stings hurt for an hour and then stop mattering. Knowing which ones are different is worth five minutes before you ever need it. A local reaction means pain, redness, and swelling around the sting site, sometimes spreading several inches. That is uncomfortable, not dangerous. Cold compress, antihistamine, and patience. A systemic reaction is a different event: hives appearing away from the sting, swelling of the lips, tongue, or throat, wheezing, dizziness, vomiting, or a racing heart. That is anaphylaxis and it is an emergency call, not a wait-and-see. The American College of Allergy, Asthma and Immunology puts life-threatening reactions to insect venom at 0.4 to 0.8 percent of children and 3 percent of adults, so adults are the more affected group. Anyone who has had a systemic reaction faces roughly a 60 percent chance of a similar or worse one next time. The CDC's figures make the pattern plain: 84 percent of American sting deaths from 2011 to 2021 were men, most of them doing outdoor work near a nest nobody knew about.
Renters, landlords, and who pays for wasp removal
Draw the line at the building envelope and most disputes resolve themselves. A colony inside the structure, in a wall void, soffit, attic, or under a slab or entry step, exists because of an opening in the building. That is normally the owner's responsibility, and so is the sealing work afterward, since an unsealed cavity is a recurring problem rather than a one-time pest. A small comb on a balcony rail, a patio umbrella, or a grill you own sits closer to routine upkeep. Many leases put that on the tenant, and given how small European paper wasp colonies stay, it is often a five minute job at night. Document either way. Photograph the entrance, note the date, and send the request in writing rather than by phone, particularly between August and October when colony size and sting risk are both at their highest. If someone in the unit has a known venom allergy, say so in the first message. That converts a maintenance ticket into a safety matter, and it should change how quickly it is scheduled.