Specialist · Aphids
Aphidius ervi
The heavy lifter of the aphid wasps — the one large enough to take potato, foxglove and pea aphid, and it works right through a short winter.
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How much, and how often
Two questions — how bad it is, and how many plants. You get a size and the dates to put it out.
How bad is it?
Pick the one that sounds like your room. If you are between two, take the higher.
How many square feet?
Six-inch pots. Count a large specimen with a dense canopy as three or four.
Your size and schedule
More about this dose
The three things people ask once they have their size. Open any of them.
Am I light, moderate or heavy?
Light
- A few large aphids on one growing tip
- No honeydew yet, or one sticky leaf
- Nothing on the plants either side of it
Moderate
- Clusters on several stems and leaf undersides
- Sticky honeydew on the leaves below
- New growth coming in curled
- Aphids turning up on a second plant
Heavy
- Stems crowded end to end
- Sooty mould on the honeydew
- Winged aphids, which means they are leaving to start colonies elsewhere
- Ants running the stems
Size matters more than count here. A large-bodied aphid — long-legged, closer to 4mm than 2 — is ervi's job. If you are looking at small round green ones, order colemani instead and you will get a better result for less money.
A colony you judged as light on Monday is a different problem by Friday, because aphids are born already pregnant. Taking the higher level costs a little more once; taking the lower one usually costs you a second release two weeks later, by which point there is more to fix.
Why more than one round?
Putting it out
- Deal with ants first. Ants farm aphids for the honeydew and will kill the wasps to protect them. A bait or a barrier, two or three days ahead.
- Take yellow sticky cards down. They catch these wasps efficiently. A few days is enough.
- Walk the space with the bottle at about 45 degrees, so any adults that have already emerged can fly out as you go.
- Spread the remaining mummies into release boxes, or onto a dry shaded surface near the aphids.
- Then leave it alone for several days while the rest emerge, and leave the mummies that appear on your leaves where they are.
Everything else is optional. Get these four and the release has done what it can.
A cleaner way
On a display plant, tip small piles into bio-boxes or paper cups hung in the branches instead of dusting the foliage. Same dose, nothing visible on the leaf.
The failure is forgetting. Very few programs fail because the mite underperformed. They fail in week five, when the plants look fine, the reorder does not happen, and the population holding the line ages out with nothing behind it.
A schedule is the same decision, made once. A bottle when it looks bad, then another when it looks bad again, is already a rhythm — just one you have to remember at the exact moment the plants look fine.
Change the size or the frequency, skip a box, pause or cancel from your account at any time.
Is this the right beneficial for your problem?
Five questions, in the order a grower actually asks them: what have you got, is this the answer to it, what will it eat, how does it do the killing, and will it survive your room.
Is this your pest?
Ervi is the heavy lifter of the aphid wasps. It is built for the big aphids, and on those it is the one to reach for. If your aphids are small, its cousin is the better buy.
Aphids cluster on stems and the undersides of new leaves, soft and pear-shaped, leaving sticky honeydew with sooty mould behind it. The large-bodied species — potato, foxglove, pea, cannabis — are long-legged and noticeably bigger, closer to 4mm than 2, and they move when you disturb them.
Ervi is a 4 to 5mm wasp, and that size is the whole point: it can handle hosts that are too large for colemani. Potato, foxglove, pea and cannabis aphid are its targets. Green peach aphid is a poor host — colemani or matricariae for those.
Then: is ervi the right answer to it?
Choose this if
Choose ervi when the aphids are the big ones. Being larger, it also searches further, so it finds scattered colonies across a bigger space than the smaller wasps will cover. It works year-round — unlike most of this catalogue it is not sensitive to day length, so a short winter is no obstacle. It cannot sting people or pets, there is nothing to mix, and no re-entry interval.
Choose something else if
Small aphids are the limit: green peach aphid is a poor host and colemani or matricariae does that job properly. Ants will defend an aphid colony and kill the wasps, so those need dealing with first. And a systemic insecticide moves into the aphid and kills the wasp developing inside — there is no compatible way to run both.
What it kills, and what it won't
Aphid mummies are not a second pest. A parasitised aphid swells into a golden-brown shell glued to the leaf, and about ten days later a new wasp chews a neat round hole out of the back of it. Those shells are the product working.
How it works
What it does to the pest, what it does on the plant, and what that leaves you looking at.
It lays inside the aphid
The female finds a live aphid and lays a single egg inside it. The larva develops in there and kills it from the inside, and the host hardens into a papery tan mummy glued to the leaf. No poison, no residue, no re-entry interval, and nothing for an aphid to become resistant to.
Damage falls faster than the kill count
Even an unsuccessful attack changes aphid behaviour: they drop off the leaf and stop feeding. So the plant starts recovering before the arithmetic says it should, and the honeydew stops before the colony looks any smaller.
Every mummy is the next release
Ten to fourteen days after release you should see golden-brown mummies, and a neat round hole in the back of one means another wasp has already gone hunting. That is why the release keeps working after the adults you bought have died.
Sugar extends them. Adults live two to three weeks with nectar or honeydew and much less without. Flowering plants nearby are functional here, not decorative.
Will it work in your room?
Deal with ants first. Ants farm aphids for the honeydew and will kill these wasps to protect the herd, so a bait or a barrier goes down before the release. And check the aphid size — ordering ervi for green peach aphid is the usual reason a release does nothing.
About Aphidius ervi
The larger of the aphid wasps at 4 to 5mm, and the one for large-bodied aphids. It cannot sting people or animals — it has no defensive stinger at all — and it cannot be talked into eating anything except aphids.
New to beneficials?
Five things that catch almost everyone the first time.
After you release it
What actually changes, how fast, and the one thing not to tidy up.
How you'll know it's working
Golden-brown mummies on the leaves within about a week to ten days. Those are wins, not new pests, and they are the clearest evidence any beneficial in this catalogue gives you.
A tiny, perfectly round hole in the back of a mummy means a new wasp has emerged and is already hunting. Aphid numbers decline from there and keep declining as long as hosts remain.
Leave the mummies alone. Each one on a leaf is an unhatched wasp. Wiping the leaves down loses that generation, so this is the rare case where leaving things a bit untidy is the better call.
Getting it to you
What is in the bottle, how it travels, and what happens if it arrives wrong.
What arrives
Mummies in a buckwheat hull carrier — aphid shells with a developing wasp inside each one, shipped in an insulated box with cold packs.
Nothing moves for the first few days, and that is exactly right. Adults chew their way out over the following days and leave a neat exit hole behind as the proof.
Release the morning it arrives. These are live organisms with a short shelf life. Walk the space with the bottle held at a shallow angle so emerged adults can fly out, then spread the remaining mummies into release boxes in dry, shaded spots.
When it ships, and when it lands
Shipping
We ship when they're ready to travel. Live orders go out Monday to Thursday. If a colony needs a beat to peak, or we're propagating a fresh batch, yours might hold up to a week. All mites and insects ship 2-day or Overnight depending on what's best for them.
When it lands
Open it that morning. Take yellow sticky cards down first. Walk through the planting holding the bottle at about 45 degrees to let any emerged adults fly out, then sprinkle the remaining mummies into release boxes or onto a dry, shaded surface near the aphids — and leave them undisturbed for several days.
About the ones that don't make it
Some of them die on the way. That is why we send more than you paid for.
A mummy is a hardened aphid the size of a pinhead, and it ships in a bottle, in a van, for two days.
Roughly 15% will not survive that. We cannot prevent it, so we price it in: the number on the label gets counted out, and then the cushion goes in on top of it.
Your 250-wasp bottle leaves here holding more than 250. The ones that do not make it are already paid for.
If you can see them
Ladybugs, lacewing larvae, Orius — the minute pirate bug — and the beetles. Tip a few onto white paper and give them twenty minutes at room temperature before you judge anybody.
Cold insects are genuinely good at playing dead. The deceased have been known to get up and walk off the counter.
Still more than about one in seven not moving? Photograph them and file a report.
The photo is not us doubting you. It is how we tell a bad batch from a bad courier day from a mailbox that hit 104°F.
If you can't see them
Mites, nematodes, eggs — and mummies, which is what this one ships as. A bottle of tan husks looks the same whether the wasps inside are alive or not, and no photograph settles that. So we don't ask you to take one.
You file the report and our entomologist takes you through the diagnostic instead — the tap test on dark paper, where the box sat, what your room was doing, and then what the pest is doing about ten days later.
The exit holes are the real answer here. Give it a few days and look for small neat round holes in the husks — that is the release working, and it is worth checking before you file anything.
Seventy-two hours from delivery, either way, with your order number. Replacement or store credit, your pick.
What it does not reach
Three gaps this page has already named, and the beneficial that closes each one.
Green peach and melon aphid want the smaller wasp
Green peach aphid is a poor host for ervi — it is simply the wrong size. Aphidius colemani is built for the small round ones and costs less. The rule of thumb is body length: a green peach aphid is about 2mm, a potato aphid closer to 4. Ordering the wrong one is the usual reason a release does nothing.
Down for the release, back up to measure it
Yellow cards catch these wasps efficiently, so take yours down for a few days around a release. Then put them back. Winged aphids on a yellow card are the early warning that a colony has started shipping out to other plants, which is exactly when you want to know.
Two cheap things that make the rest work harder. Blue cards give you the dated count this page keeps asking you to read. Breeder's Blend is pollen and Artemia; it keeps the population fed through the lull when prey gets scarce.
Questions
Will these wasps sting me, my family, or my pets?
No. Aphidius ervi is a "micro-wasp" that is physically incapable of stinging humans or animals. They do not have a defensive stinger like a yellowjacket; their only interest is finding large-bodied aphids to parasitize, making them 100% safe for indoor use.
How do I know if they are actually working?
Check your aphid colonies about 10–14 days after release. You should see "mummies"—aphids that have turned into bloated, golden-brown shells. If you see a tiny, perfectly round hole in the back of the mummy, it’s proof a new wasp has emerged and is already hunting the next generation of pests.
What makes A. ervi different from other parasitic wasps?
A. ervi is the "heavy lifter" of the Aphidius family. While other species target small aphids, A. ervi specifically hunts larger species like Potato, Foxglove, and Cannabis aphids. Because they are larger, they also have a greater searching capacity to find pests across bigger distances.
Can I use these alongside my current pest sprays?
These beneficials are highly sensitive to broad-spectrum chemical insecticides: pyrethroids are 8–12 weeks, bifenthrin 12–15, neonicotinoids 21 days after a foliar spray and 4 weeks after a soil drench. They are generally compatible with "soft" options — horticultural oil is done once it has dried, insecticidal soap needs a day.
Do I need to get rid of the ants on my plants first?
Yes, ant control is critical. Ants "farm" aphids for their honeydew and will aggressively protect them by killing the A. ervi wasps. For the best results, use a bait or barrier to manage the ants so your wasps can work undisturbed.
How long can I keep them in the bottle before releasing?
These are live organisms with a short shelf life. For maximum efficiency, you should release them on the day they arrive. If you must wait, store the bottle in a cool, dark place at 40°F – 50°F for no more than 48 hours.