For non-aggressive wasps I've had great luck spraying nests with this Spectracide wasp remover in the evening. For a nest up high in an eave, soffit, or tree, this Gotcha pole adapter clamps onto the can so you can spray from the end of an extension pole and treat the nest from 10+ feet away instead of standing right under it. And for anything aggressive I wear this ridiculous-looking upper torso beekeeping suit and keep my distance. It seems silly, but trust me, I learned the hard way.
The smallest insect ever described is a wasp. Not a gnat, not a thrips, not a flea — a wasp. A male fairy wasp called Dicopomorpha echmepterygis measures about 0.139 millimeters from end to end, which makes it smaller than a large single-celled Paramecium and roughly half the width of the period at the end of this sentence. It is blind, wingless, mouthless, and it spends its entire adult life inside or beside the egg of a barklouse.
Fairy wasps — also called fairyflies, though they are wasps and not flies at all — are a family of about 1,400 described species that live almost entirely out of human sight. You share your yard with them right now. They are working in your garden for free, killing the eggs of leafhoppers and plant bugs before those pests ever hatch, and they are physically incapable of stinging you.
This guide covers what fairy wasps are, how small “small” actually gets, how to tell a genuine tiny wasp from the other minute insects on your window sill, and what those tiny wasps in your house are most likely to be. For the wider group these insects belong to, see our parasitic wasp guide. For the opposite extreme, see the biggest wasp in the world.
Fairy wasps make up the family Mymaridae, part of the enormous superfamily Chalcidoidea — the same broad group that contains the chalcid wasps homeowners occasionally find indoors. Roughly 1,400 species in about 100 genera have been described, and specialists broadly agree that many more remain unnamed. They occur on every continent except Antarctica and in essentially every terrestrial habitat, from rainforest canopy to suburban lawns.
Every known fairy wasp is an egg parasitoid. The female does not hunt caterpillars or paralyze spiders the way larger wasps do. She searches plant tissue for the freshly laid eggs of other insects, inserts a single egg of her own inside one of them, and leaves. Her larva consumes the contents of that host egg from the inside, pupates in the shell, and chews its way out as an adult. The host egg never hatches.
Their most common hosts are true bugs in the order Hemiptera — leafhoppers, planthoppers, plant bugs, and their relatives — though various species attack the eggs of beetles, barklice, thrips, flies, and other insects. In practical terms, a fairy wasp is a pest-control device that operates one generation earlier than almost anything else in your garden: it removes the pest before it becomes a feeding, reproducing insect.
The name “fairyfly” comes from the wings. A fairy wasp forewing is not a flat membrane but a narrow paddle or racket on a long stalk, edged with a fringe of stiff hairs. Under a microscope the effect is genuinely delicate — hence the fairy — but the insect is a wasp in the order Hymenoptera, as much a wasp as a yellowjacket is.
Most fairy wasps measure between 0.5 and 1.0 mm. The family as a whole spans roughly 0.13 mm to about 5.4 mm. The record-holders sit at the bottom of that range:
| Species | Size | Record |
|---|---|---|
| Dicopomorpha echmepterygis (male) | ~0.139 mm | Smallest adult insect ever described |
| Kikiki huna (female) | ~0.15 mm | Smallest known flying insect |
| Typical fairy wasp | 0.5–1.0 mm | Normal for the family |
| Largest fairy wasps | up to ~5.4 mm | Still smaller than a grain of rice |
The 0.139 mm record belongs to a male, and that matters. In Dicopomorpha echmepterygis, the sexes are wildly different animals. Females are winged, sighted, and around 0.55 mm — small, but recognizably a wasp. Males are a reduced life-support system for sperm: no wings, no eyes, no functional mouthparts. They never leave the vicinity of the host eggs they emerged from, and they never need to eat, because they do not live long enough for it to matter. The host, appropriately obscure, is the egg of a barklouse, Echmepteryx hageni.
Kikiki huna, first described from Hawaii and since found in Costa Rica and Trinidad, holds the more impressive record in engineering terms: at roughly 0.15 mm it is the smallest insect known that actually flies.
For contrast, a honeybee is about 12 mm and the largest wasps have bodies approaching two inches. From the smallest fairy wasp to the largest hornet, body length inside this one insect order spans more than two orders of magnitude.
Miniaturization at this scale is not simply a matter of scaling everything down. Two constraints dominate.
Air stops behaving like air. At the size of a fairy wasp, airflow is dominated by viscosity rather than momentum — from the wasp’s point of view, flying is closer to swimming through honey than gliding through a gas. Insects this small cannot generate lift with conventional flapping. Instead they use a “clap-and-fling” stroke, bringing the wings together above the body and peeling them apart to create a vortex on each downstroke. The hair fringe on the wing margin appears to reduce drag during that motion while still catching enough air to be useful. It is a wing built of bristles rather than sheet, because a sheet at that size would cost more than it earns.
There is not enough room for a normal nervous system. The most striking demonstration comes from a close chalcidoid relative, Megaphragma mymaripenne — whose species name means “fairy-winged,” though it belongs to the neighbouring family Trichogrammatidae rather than to the true fairyflies. At around 0.2 mm it carries roughly 7,400 neurons, and in the adult the great majority of them have lost their cell nuclei entirely. The nuclei are used during development and then discarded to free up space. The insect flies, walks, finds hosts, and reproduces with a brain made largely of neurons that have thrown away their own genetic control centres. Our wasp anatomy guide covers the more familiar end of wasp body structure.
No. Fairy wasps cannot sting people, pets, or anything else your size.
Like all female wasps, a fairy wasp has an ovipositor — the egg-laying tube that in social wasps like paper wasps and yellowjackets has been repurposed into a venom-injecting stinger. In fairy wasps it has not been repurposed. It is used for exactly what it looks like: threading a single egg through the shell of another insect’s egg. It is a precision instrument measured in micrometers, with no venom reservoir capable of affecting a mammal and no mechanical hope of penetrating human skin.
This is true of parasitoid wasps generally, and it is the single most useful fact about them for a nervous homeowner: the tiny wasp on your window glass is not a threat. If you want the full picture of which wasps sting and why, see do wasps sting? and the wasp stinger anatomy guide.
Honest answer first: you almost certainly cannot identify a fairy wasp with the naked eye. At half a millimeter, an insect reads as a speck that moves. Confident family-level identification is microscope work, and the diagnostic characters — the arrangement of grooves on the face between the antennal sockets, the number of tarsal segments — are not visible on a phone photo.
What you can do is narrow things down. If you have a hand lens or can get a macro shot, these features separate a fairy wasp from the other minute insects that turn up indoors:
What a fairy wasp is not: metallic and stout-bodied (that suggests a chalcid or cuckoo wasp), fuzzy (that suggests a tiny bee or a moth), or jumping (that suggests a flea or a springtail). For the broader problem of misidentified insects, see bugs that look like wasps.
“Tiny wasp” is a common household search, and fairy wasps are rarely the answer — not because they are absent from your property, but because they are too small to notice indoors and have no reason to come inside. Insects the size of a period do not trigger the “what is that?” reflex.
When a homeowner does spot a small wasp-like insect indoors, these are the usual suspects:
| What you’re seeing | Likely identity | What it means |
|---|---|---|
| 1–3 mm, dark or metallic, on windows | Chalcid or other parasitoid wasp | Emerged from a host insect indoors — often stored food pests or overwintering flies. Harmless. |
| 2–5 mm, black, crawling then flying | Winged ant (not a wasp) | Usually a mating flight; check for an established colony. |
| 2–4 mm, dark, drifting weak flight near houseplants | Fungus gnat (a fly) | Overwatered potting soil. |
| 1–2 mm, slender, at windows in numbers | Thrips or a small parasitoid | Blew in, or emerged from cut flowers. |
| 5–8 mm, black, abdomen flicked up like a flag | Ensign wasp | Develops in cockroach egg cases — harmless itself, but worth checking for roaches. |
Tiny parasitoid wasps indoors are almost always a symptom rather than a problem. They emerged from something, and the useful question is what. A recurring supply of small parasitoids in a kitchen often traces back to an infested bag of flour, birdseed, or dried pet food; in an attic or upstairs window, it frequently traces to cluster flies or other overwintering insects. Vacuum the wasps, find the host material, and both disappear. The parasitic wasps indoors section of our hub guide walks through this in more detail.
The fairy wasp life cycle is brief and entirely tied to host eggs. A female locates a suitable egg — often by detecting chemical traces the host left while laying — inserts one of her own eggs, and moves on. Development inside the host egg typically takes a couple of weeks depending on species and temperature. Adults are short-lived, in many species just a few days, and females are usually ready to lay almost immediately on emergence. Several generations can stack up in a single warm season.
One group has taken this in a strange direction. A handful of species, including Caraphractus cinctus, are aquatic. The female swims underwater using her wings as oars to reach the submerged eggs of water beetles, and can remain below the surface for days at a time. A wasp that rows is an odd thing to picture, but at that scale the distinction between swimming and flying is less meaningful than it sounds.
Because they attack eggs, fairy wasps are valuable in agriculture, and several have been deployed deliberately:
In a home garden, nobody releases fairy wasps — they are already there. What you can do is avoid killing them. Broad-spectrum insecticides are indiscriminate, and an insect weighing a fraction of a milligram has no margin. Practically:
That advice holds for the whole parasitoid guild, not just fairy wasps. See our guides to braconid wasps and ichneumon wasps for the larger and more visible members of the same team.
What is the smallest wasp in the world? Dicopomorpha echmepterygis, a fairy wasp whose males measure about 0.139 mm. It is also the smallest adult insect of any kind that has been formally described. The smallest known flying insect is another fairy wasp, Kikiki huna, at roughly 0.15 mm.
Are fairy wasps dangerous? No. They cannot sting, they cannot bite through skin, they do not carry disease, they do not damage homes, and they do not feed on anything in your house. They are among the most harmless insects you will ever share a building with.
Why are they called fairyflies if they’re wasps? For the fringed, stalked, delicate wings. The “-fly” ending is an old common-name convention rather than a statement about classification; fairy wasps are Hymenoptera, not Diptera. “Fairy wasp” is the more accurate name.
Can I see a fairy wasp without a microscope? Rarely, and not in any detail. A large fairy wasp at 1 mm is visible as a moving speck in good light. The record-holders are below the resolution of the human eye at normal viewing distance.
Are the tiny wasps in my window fairy wasps? Probably not. Anything you notice unaided on a window is more likely a chalcid wasp, another small parasitoid, a winged ant, or a fungus gnat. All of those are harmless too, but the fix differs — see the table above.
Do fairy wasps live in nests? No. They are solitary parasitoids with no nest, no colony, no queen, and no workers. Nest-building and colony defence — the behaviours that make wasps a homeowner problem — belong to the social species covered in our wasp nest guide.
Should I try to get rid of fairy wasps? No, and you could not do it selectively if you tried. They suppress garden pests at no cost to you and pose no risk whatsoever.
Fairy wasps are the reason the answer to “what is the smallest insect in the world?” is a wasp. About 1,400 described species, all of them egg parasitoids, most of them well under a millimeter, with the record-holder at 0.139 mm — blind, wingless, and smaller than some single-celled organisms. They are present across almost every landscape on Earth, including yours, and the overwhelming majority of homeowners will never knowingly see one.
For practical purposes, three things matter. Fairy wasps cannot sting you. Any tiny wasp you actually notice indoors is probably a different parasitoid and is also harmless, though it is worth finding what it emerged from. And the tiny wasps in your garden are doing free pest control that no spray can replicate — which is a good argument for keeping the sprayer in the shed.