Does Aphidius colemani work against aphids in hydroponics? Yes, against smaller aphids. Aphidius colemani is a tiny parasitic wasp that lays eggs inside green peach aphids and melon or cotton aphids, turning them into “mummies.” UConn Extension says it is not effective against larger foxglove or potato aphids. Release it early, ideally with banker plants, before aphids build up.
Key takeaway: Aphidius colemani is a host-specific parasitoid sold as aphid mummies. It works best as prevention: West Virginia University warns that waiting for the first aphid is too late, because new adult wasps take three to four weeks to appear. Banker plants of wheat or barley carrying cereal aphids keep wasps breeding in your grow space.
| Fact | What sources report | Source |
|---|---|---|
| Good targets | Green peach aphid, melon/cotton aphid | UConn Extension |
| Poor targets | Foxglove aphid, potato aphid | UConn Extension |
| Adult life | About 1 week | Danish EPA |
| Egg to adult | 10–13 days | Danish EPA |
| Best temperature | 72–77°F (22–25°C) | Danish EPA |
| Banker host | Bird cherry-oat aphid on wheat or barley | UVM; UConn |
What Is Aphidius Colemani?
Aphidius colemani is a small parasitic wasp used in greenhouses to manage aphids. UConn Extension calls it host specific: it parasitizes smaller species such as green peach aphid (Myzus persicae) and melon or cotton aphid (Aphis gossypii). The female lays an egg inside an aphid, the larva develops inside it, and the dead aphid becomes a hardened mummy.
The Danish Environmental Protection Agency lists 300–390 eggs per female, development in 10–13 days and adult survival of about one week. Those numbers explain why steady, repeated releases or a banker system work better than a single shipment.
Which Aphids Does Aphidius Colemani Control?
It controls smaller aphids, mainly green peach aphid and melon or cotton aphid. UConn says it is not effective against larger aphids such as foxglove aphid (Aulacorthum solani) or potato aphid (Macrosiphum euphorbiae). Identify your aphid first; for large aphids, UConn suggests banker plants that support the predatory midge Aphidoletes aphidimyza.
| Aphid | Aphidius colemani? | Source |
|---|---|---|
| Green peach aphid | Yes | UConn Extension |
| Melon/cotton aphid | Yes | UConn Extension |
| Foxglove aphid | Not effective | UConn Extension |
| Potato aphid | Not effective | UConn Extension |
Our guide to hydroponic pests like aphids and mites helps with identification.
How Do You Release Aphidius Colemani?
Release it as soon as plants go in, not after aphids appear. Suppliers ship it as parasitized aphid mummies in vermiculite, per University of Vermont. Sprinkle the mummies onto banker plants or near infested plants, as UVM describes for banker pots. West Virginia University says it takes three to four weeks before new adult wasps are produced.
- Order before the crop arrives.
- Place mummies near infested plants or on banker pots.
- Release weekly while the crop is at risk.
- Check leaves weekly for new mummies.
- Avoid pesticides on or near the release area.
The Danish EPA lists preventive rates as low as 0.15 wasps per 10.8 sq ft (1 m²) weekly, with higher rates when aphids are present. Follow your supplier’s rate.
How Do Aphidius Colemani Banker Plants Work?
Banker plants are pots of wheat or barley infested with bird cherry-oat aphid, a cereal aphid that does not attack most greenhouse crops. UVM says Aphidius breeds on these aphids and disperses into the crop to find pest aphids. UConn found the aphids reproduce best on wheat and poorly on oats, so wheat is the safest choice.
- Start early: WVU recommends two banker plants per greenhouse, adding one each week.
- Keep them fresh: sow new grain pots weekly.
- Check mummies: UConn advises weekly checks for new mummies.
- Never spray: UConn says do not treat banker plants with pesticides.
Keep banker pots in their own containers beside a hydroponic system so grain roots and media stay out of your channels.
How Do You Set Up Aphidius Colemani Banker Plants Step by Step?
UConn Extension gives a simple sequence. Order starter banker plants up to six weeks before production, move them into 10–12 inch (25–30 cm) pots so they stay moist, and wait one to two weeks for the cereal aphids to build up. Then lightly distribute Aphidius colemani over the banker plants and check weekly for new mummies.
- Order starter banker plants up to 6 weeks ahead.
- Transplant into 10–12 inch (25–30 cm) pots.
- Let cereal aphids build for 1–2 weeks.
- Release Aphidius colemani over the banker plants.
- Seed new pots weekly or biweekly; UConn says bankers decline within weeks.
- Move aphids from old to new bankers every 2 weeks.
UConn notes suppliers suggest one to 10 banker plants per 10,000 sq ft (929 m²), placed along walkways and near the crops you want protected. Use untreated seed and keep pesticides, including fungicides and growth regulators, off banker plants.
What Are Hyperparasites in Aphidius Colemani Systems?
Hyperparasites are tiny wasps that lay eggs inside Aphidius that has already parasitized an aphid. UVM says you can spot them because the exit hole in the mummy is jagged and uneven instead of smooth and round. They can wipe out an Aphidius population, so UVM and UConn advise destroying banker plants at the end of the season.
If you see jagged exit holes, replace banker plants and restart with fresh material. Pair Aphidius with other tactics from our guide to ladybugs for aphids.
What Conditions Does Aphidius Colemani Need?
Moderate warmth. The Danish EPA lists an optimum of 72–77°F (22–25°C), a minimum around 37–41°F (3–5°C) and a maximum around 86°F (30°C). Keep humidity and airflow normal for your crop, and avoid broad-spectrum sprays that kill wasps. Check quarantining new plants and clones so aphids do not arrive in large numbers.
FAQ About Aphidius Colemani
Why use banker plants for Aphidius colemani?
UConn says banker-reared wasps are more often female, larger and longer-lived.
How do I know Aphidius colemani is working?
Look for new aphid mummies with smooth, round exit holes.
Does Aphidius colemani work on potato aphids?
No; UConn says it is not effective on potato or foxglove aphids.
How long do Aphidius colemani adults live?
About one week, according to the Danish EPA.
Are oats good Aphidius colemani banker plants?
UConn found cereal aphids did poorly on oats; wheat worked best.
Where should Aphidius colemani banker plants go?
UConn says along walkways, at bench ends and near the target crops.
Can Aphidius colemani work in a small grow tent?
Yes, if aphids are the small species it targets and releases start early.
Sources
- UConn Extension — Aphid banker plants
- West Virginia University Extension — Control pests with banker plants
- University of Vermont — Aphid banker plant system for greenhouse IPM
- Danish Environmental Protection Agency — Beneficial arthropods table
- Photo credits (Wikimedia Commons, edited with titles): Aphidius colemani by Laura Sorrensen at Pxhere 1453109 by Laura Sorrensen at Pxhere (CC0); Aphidius colemani 197617580 by Gianni Del Bufalo (CC BY 4.0)