For non aggressive wasps I've had great luck spraying the nests with this Spectracide wasp remover in the evening. For more aggressive wasps I also use this rediculous looking upper torso Beekeeping suit. It seems silly, but trust me, it's amazing.
You’re working in the garden or walking through the yard when you spot a wasp-like insect with a startlingly long tail — sometimes longer than its entire body. Your first reaction is probably alarm. Is it dangerous? Is it building a nest nearby? Should you call an exterminator?
The good news is that nearly every wasp species with a notably long tail is either harmless or actively beneficial. That intimidating “tail” is almost never a stinger. Once you understand what you’re actually looking at, these insects go from scary to fascinating — and you’ll probably want them to stay.
This guide covers the most common wasps with long tails, explains what that “tail” actually is, and helps you decide what (if anything) to do when you find one.
When homeowners report seeing a “wasp with a long tail,” the “tail” is almost always one of three things:
An ovipositor — This is an egg-laying organ that some female wasps use to deposit eggs deep inside wood, insect hosts, or plant tissue. In ichneumon wasps and wood wasps, the ovipositor can extend several times the length of the body. It looks exactly like a stinger but serves an entirely different function and poses no threat to humans.
A highly elongated petiole — The petiole is the narrow “waist” that connects a wasp’s thorax to its abdomen. In thread-waisted wasps, this section is stretched into an extraordinarily long, thin stalk that gives the insect an exaggerated hourglass silhouette. The elongated waist can look like a tail attached to the back of the wasp.
An elevated, flag-like abdomen — Ensign wasps carry their small abdomen on a long petiole in an elevated, bobbing position that looks nothing like a typical wasp. The abdomen resembles a tiny flag or pointer, which can look like an odd appendage from certain angles.
Understanding which type you’re looking at is the first step to correct identification.
Ichneumon wasps are the most likely explanation when a homeowner reports a wasp with an extremely long tail. With over 100,000 known species worldwide, ichneumon wasps form one of the largest animal families on Earth — and several thousand species are found across North America.
Appearance: Most ichneumon wasps are slender with a narrow waist. Their size ranges from tiny (less than 1/4 inch) to impressively large (over 2 inches in body length, not counting the ovipositor). Coloring varies widely from solid black or brown to banded yellow and black. The defining feature is the ovipositor, which extends from the tip of the abdomen and can range from barely noticeable to several times longer than the entire insect.
What the “tail” is: The ovipositor is used to lay eggs inside or on caterpillars, beetle larvae, or other insects that will serve as food for the ichneumon’s young. It is not a stinger and is not used for defense.
Behavior: Ichneumon wasps are parasitoids — their larvae develop inside or alongside a host insect, eventually killing it. They are nature’s pest controllers, targeting caterpillars, wood-boring beetles, and other insects that damage gardens and trees. Adult ichneumons feed on nectar and plant fluids.
Danger level: Very low. Females technically possess a modified ovipositor that could deliver a mild sting if you grabbed one forcefully, but ichneumon wasps do not sting defensively under normal circumstances. They will not attack you, sting without provocation, or build colonies near your home. Most are completely oblivious to human presence.
What to do: Nothing. Leave them alone and let them work. They are valuable predators of pest insects.
The giant ichneumon wasps of the genus Megarhyssa deserve special mention because their ovipositors are so dramatically long that they generate the most homeowner alarm calls of any beneficial wasp.
Appearance: Megarhyssa macrurus, the most commonly encountered species, has a body length of about 1.5 to 2 inches — and an ovipositor that can measure 3 to 4 inches or more. The total length from head to ovipositor tip can exceed 6 inches. The body is brown and yellow, and the ovipositor emerges in a long, hair-thin filament that often trails behind the insect in flight.
What they do: Female giant ichneumon wasps locate the tunnels of pigeon tremex (a type of wood wasp) inside dead or dying trees. They drill through the bark and wood with their long ovipositor — a remarkable feat — and lay a single egg on the pigeon tremex larva. Their larva then consumes the host.
Danger level: Zero. The ovipositor is designed for drilling through wood, not for stinging. These wasps cannot sting you. A female may attempt to oviposit on a bare arm or hand if she mistakes a pore in your skin for a wood tunnel (a rare but documented event), but this results in no injury and no venom.
Where you’ll find them: Near dead or dying hardwood trees — particularly elms, maples, and beeches — in late spring and summer. Females can often be found hovering close to tree trunks, slowly probing the bark with their antennae.
Thread-waisted wasps get their name from their remarkably narrow, elongated petiole — the connection between thorax and abdomen. This stretched waist gives the appearance of a tail or a long, thin extension of the body behind the wings.
Appearance: Most thread-waisted wasps are 0.5 to 1.5 inches long with a very slender, often reddish-orange or black and orange abdomen. The narrow waist segment can be nearly as long as the abdomen itself, creating a distinctly unusual silhouette. In flight, the abdomen often hangs below the thorax, which adds to the “tailed” appearance.
What they do: Thread-waisted wasps are solitary hunters. Different species target different prey — caterpillars, crickets, grasshoppers, or other insects. A female catches and paralyzes a prey item, carries it to a burrow in bare soil, lays an egg on it, and seals the burrow. The larva feeds on the paralyzed prey.
Danger level: Low. Thread-waisted wasps are solitary and non-aggressive. They do not defend territories or nests from humans. A female could sting if you restrained her, but under normal circumstances you would have to work very hard to get stung. They pose no threat when encountered in the garden.
Where you’ll find them: Hovering low over bare or sandy soil (where they nest), visiting flowers for nectar, or carrying prey in flight. Common in gardens, lawns, and open areas throughout North America from late spring through fall.
Wood wasps — often called horntails — are large, robust wasps that are frequently mistaken for dangerous hornets or yellow jackets. Many species have a short, sharp-looking spike at the tip of the abdomen, which is the ovipositor. While not as dramatically long as in ichneumon wasps, this spike looks alarming.
Appearance: Horntails are 1 to 1.5 inches long, stocky, and often boldly colored in black and yellow, black and orange, or solid metallic blue-black. The “horn” or “tail” spike at the rear is actually the ovipositor (in females) and is used to drill into wood to lay eggs. Both sexes also have a small spine on the back of the thorax.
What they do: Female horntails lay eggs deep inside the wood of weakened, dying, or recently dead trees. The larvae bore through the wood for one to several years before emerging as adults. They are not interested in structural lumber under normal conditions, though they occasionally emerge from firewood or lumber used in construction.
Danger level: None. Horntails cannot sting. The ovipositor is used only for drilling into wood. Despite looking intimidating, they are among the most completely harmless large insects you’ll encounter.
Where you’ll find them: Around dying or recently cut trees, firewood piles, or occasionally emerging from wooden structures. Most active in summer.
For a detailed look at this group, see our Wood Wasp Complete Homeowner Identification Guide.
Ensign wasps have a unique and distinctive appearance that confuses many homeowners. Their tiny, triangular abdomen is attached by a very thin petiole and held elevated above the body, waggling as they walk. The abdomen looks like a flag or “ensign” — hence the name.
Appearance: Small (1/4 to 1/2 inch), solid black, with a distinctive jerky walk. The abdomen is small and oval, and it bobs up and down as the wasp moves.
What they do: Ensign wasps are parasites of cockroach egg cases. Females find cockroach oothecae (egg cases) and lay a single egg inside. The larva consumes the cockroach eggs. Finding ensign wasps in your home actually indicates cockroaches are present — they are good indicators of pest activity.
Danger level: Zero. Cannot sting, poses no harm.
As a general rule: No. The wasps with the most dramatic and alarming “tails” are uniformly the least dangerous ones.
This is actually logical when you think about it. The long “tail” is an ovipositor — an egg-laying tool — not a stinger. Wasps that invest heavily in ovipositor development tend to be solitary parasitoids or wood-borers with no colony to defend and no reason to attack humans.
The species you should be cautious about — yellow jackets, paper wasps, and bald-faced hornets — all have modest-looking, barely visible stingers at the tip of a compact abdomen. They look ordinary, not dramatic.
The few situations where a long-tailed wasp could sting involve physically handling the insect roughly. If you pick up a female ichneumon wasp and squeeze her, she could sting. But this isn’t defensive aggression — it’s a last-resort response to direct physical threat. Leave them alone and you’ll never be stung.
Do nothing — the most appropriate response in nearly every case. Long-tailed wasps are beneficial predators and parasites that control caterpillars, beetles, cockroaches, and other pest insects. Removing them makes your yard and garden less healthy.
Watch them — giant ichneumon wasps drilling into tree bark with their impossibly long ovipositor is one of the more spectacular things you can witness in a backyard. If you spot one, take a few minutes to observe.
Identify what they’re feeding on — if you’re finding many ichneumon wasps near a specific tree, it may indicate a healthy population of parasitoid wasps responding to a wood-boring beetle infestation in that tree. The wood-borers may be a concern; the ichneumons attacking them are your allies.
Contact a professional if needed — if you’re uncertain whether what you’re seeing is a beneficial long-tailed wasp or an aggressive stinging species, a pest control professional or local university extension service can help with identification. The wasp identification hub covers over 19 species to assist with recognition.
| Feature | Likely Species | Danger |
|---|---|---|
| Very long filament, thinner than a thread | Ichneumon wasp or Giant ichneumon (Megarhyssa) | None |
| Long, thin waist; body hangs below wings | Thread-waisted wasp | Very low |
| Stocky body, short spike at rear | Wood wasp / Horntail | None |
| Tiny black wasp, bobbing abdomen | Ensign wasp | None |
| Short, tucked stinger, striped abdomen | Yellow jacket or paper wasp | High |
If the “tail” is short, barely visible, and tucked under a compact abdomen — and if the insect is aggressive or hovering near a paper nest — you are looking at a stinging species that warrants caution. For those species, see our guides on paper wasp nests and wasp sting treatment.
A wasp with a long tail is almost certainly beneficial and poses no real threat to your household. The dramatic “tail” you’re seeing is nearly always an ovipositor — an egg-laying structure used to parasitize pest insects or lay eggs in wood. Ichneumon wasps, giant ichneumons, thread-waisted wasps, horntails, and ensign wasps all fall into this category.
The instinctive alarm you feel when you see one of these insects is understandable, but the correct response is to appreciate what you’re looking at. These are nature’s pest controllers at work.
For a broader overview of wasp species identification, visit our complete wasp identification guide. To learn more about specific long-tailed species, explore our detailed guides on ichneumon wasps and thread-waisted wasps.