Do Wasps Come Out at Night? Most Don't. Here Are the Exceptions

The main exception in the U.S. is the European hornet, which flies both day and night and is drawn to lights (UMD). Some harmless parasitic wasps also fly at night. Knowing which is which matters if you plan to deal with a nest.

Graphic: summary of this guide, made by our team from the cited sources.

Which wasps are out after dark?

Wasp	Active at night?	Stings?	Source
Yellowjackets	No, mostly in the nest	Yes, defend nest strongly	Univ. of Kentucky
Baldfaced hornet (an aerial yellowjacket)	Mostly in the nest; can be drawn to lights	Yes	Univ. of Kentucky, NC State
Paper wasps	No, mostly on the nest	Yes, less defensive	Univ. of Kentucky, UMD
European hornet	Yes, flies day and night	Yes	UMD, Ohio State
Enicospilus (ichneumon) wasps	Yes, nocturnal	No, stingless	NC State

Why most wasps stay in at night

Social wasp workers forage for nectar, sugary liquids and insect prey to feed their young (UMD). After dark the foragers come home. The colony is still alive inside, and it will still defend the nest if disturbed, but most wasps aren't flying.

That's the reasoning behind a common extension recommendation. The University of Kentucky says that while "it's best to treat all wasp and hornet nests at night," homeowners dealing with hornets should do so at night "when most of the insects are in the nest and less active," and yellowjacket nests should be treated at night for the same reason (Univ. of Kentucky).

The exception: European hornets

The European hornet is the only true hornet established in the U.S. It's large, ¾ to 1⅜ inches long, reddish-brown with yellow on the abdomen and face (UMD).

It flies at night. Ohio State calls it "one of the few hornet species that flies at night." It's often found at windows, attracted to light from inside homes, barns and garages, and can act aggressively toward headlights, floodlights and porch lights that shine toward its nest (Ohio State). UMD adds that it may be attracted to a flashlight and can collide with windows (UMD).

Its nest is hidden. European hornets nest in cavities: hollow trees, attics, barns, wall voids and shutters, usually with an entry 6 feet or more above the ground (Ohio State). At their largest, nests may contain 200-400 workers (Ohio State); UMD says larger nests can exceed 1,000 (UMD).

Seeing them at your light doesn't mean the nest is next door. NC State notes that European hornets can fly a good distance from their nest, so lights alone don't prove a colony is nearby (NC State). They also say late summer brings more of them, because colonies are reaching hundreds of individuals by then.

The harmless night flyer: Enicospilus wasps

If the "wasp" at your light is about an inch long, mottled tan, orange and brown, with dark eyes, it may be an Enicospilus wasp. NC State describes these as "large, stingless wasps that are commonly found at porch lights" because they fly at night. They parasitize caterpillars of large moths and, since they don't defend colonies, "they are harmless to humans." Their size and shape can make them look like crane flies (NC State).

No action needed. Turning off the light is enough if they bother you.

When in the year wasps are most active

Time of year matters as much as time of day. UMD describes the yearly cycle of a social wasp colony (UMD):

• Spring: a single queen comes out of winter shelter and starts a small nest alone.
• Summer: workers take over building and foraging. The colony keeps growing.
• Late summer to early autumn: the colony hits its largest size. New queens and males are raised, and UMD notes workers "might be more easily agitated and defensive of a disturbed nest" at this stage.
• Winter: freezing weather ends the colony. Only young mated queens survive, sheltering elsewhere, and the old nest isn't reused.

That's why late summer brings the most stings and the most wasps at porch lights. NC State noted the same pattern for European hornets at lights in August, when colonies were reaching hundreds of individuals (NC State). If a nest is out of the way, UMD and Kentucky both point out you can simply wait for a hard frost to end it (UMD; Univ. of Kentucky).

Do wasps sleep?

Our sources don't use the word "sleep." What they describe is that most social wasps are in the nest and less active at night (Univ. of Kentucky). They are still able to respond if the nest is disturbed, so "inactive" doesn't mean "safe to touch."

What this means if you're dealing with a nest

For yellowjackets and most hornets, night is the safer time. The University of Kentucky recommends (Univ. of Kentucky):

1. Find the nest opening in daylight so you know where to aim after dark.
2. Approach slowly at night.
3. Don't shine the flashlight directly into the entrance, which can startle the wasps and make them fly toward the light. Light the opening from the side, and if possible set the light on the ground instead of holding it.
4. For hornets, wear a full wasp suit and head veil sealed at the wrists, ankles and collar, and don't break the paper envelope of the nest.
5. Wait at least 3-4 days before removing a treated hornet nest.

UMD also advises never shining a light at a nest entrance (UMD).

For paper wasps, Kentucky says daytime treatment can work if you don't stand directly under the nest (Univ. of Kentucky).

For European hornets, night isn't much safer. Ohio State notes that because they fly at night, "unlike other common nuisance wasps, the risk of being stung does exist when treating after dark." Wear protective clothing, follow the label, and consider hiring a professional (Ohio State).

Never block a nest entrance in a wall. Ohio State warns that hornets can chew new exit holes through drywall and come out inside the house (Ohio State).

Always read the label. Ohio State's fact sheet ends with "The label is the law for pesticide use" (Ohio State).

Call a professional if the nest is high, inside a wall, or if anyone in the house is allergic to stings. Kentucky notes that allergic reactions to wasp and hornet stings account for about 225,000 emergency room visits a year in the U.S. (Univ. of Kentucky).

Cutting down on wasps at your lights

• Turn off outdoor lights or switch to motion-activated lights (UMD).
• Close the blinds. Ohio State says turning off lights or drawing the blinds can help (Ohio State).
• Use warmer bulbs. UMD says LED bulbs with a warmer color temperature (yellower light) have been shown to attract fewer insects overall than bluish-white light (UMD).
• Don't point floodlights at a known nest (Ohio State).

If you're not sure what kind of nest you have, our guide to what wasp nests are made of shows how to tell them apart.