Aphidius colemani is a parasitic wasp used for the biological control of small aphid species in greenhouse and indoor growing environments. It is one of the most commonly used aphid parasitoids due to its fast action, strong searching ability, and ease of blending into integrated pest management programs.

This beneficial insect is especially effective against aphids such as the green peach aphid, the tobacco aphid, and the cotton aphid, which reproduce quickly and can overwhelm crops if left unmanaged.

Rather than feeding on aphids like predators do, Aphidius colemani controls aphids by parasitizing them, stopping reproduction and reducing populations over time.

Here’s What They Look Like at Different Stages of Their Life:

Because parasitic wasps are small and discreet, many new growers are unsure what to look for after release.

• Egg: Eggs are laid inside the aphid and cannot be seen.
• Larval: The larva develops inside the aphid, feeding internally. During this time, the aphid becomes sluggish and stops reproducing.
• Pupal (mummy): The aphid turns into a swollen, tan to golden-brown shell called a mummy. These mummies remain attached to leaves and are the most visible sign that control is working.
• Adult: Aphidius colemani adults are very small, slender wasps, about 2–3 mm long. A male wasp has slightly longer antennae, a rounded abdomen that is shorter than the wings, and is black with dark brown legs. A female has a more pointed abdomen that is as long as the wings, is equipped with an ovipositor, and is black, with light brown legs.

Behavior: A. colemani has a very effective searching behavior, which enables the wasps to track down and parasitize aphids, even when they are at low density.

Why Growers Love It:

• Fast-acting control of small aphid species
• Actively searches crops for aphids
• Builds its own population in the crop
• Easy to integrate into IPM programs
• Safe for people, plants, and beneficial insects

Timing is critical to achieving success with parasitic wasps. They perform best when introduced before pests reach outbreak levels.

Preventive use:

• ID aphid to ensure it is the Cotton aphid (Aphis gossypii), the Green peach aphid (Myzus persicae), or the Tobacco aphid (Myzus nicotianae)
• Apply early when aphids are first detected or when aphids are expected based on past crop history.

Curative use:

• Effective when small aphid species are already present, especially at low to moderate population levels.
• Multiple releases will be required if pest pressure is high or crop is mature and dense.

Environmental Conditions:

• Performs best between 20–25°C, with activity decreasing below 15°C or above 30°C.
• Suitable for vegetables, ornamentals, herbs, and indoor plant production.

Note: Monitoring is essential. After 14-21 days from the first release, inspect leaves, flowers, and fruit clusters to determine if additional releases are required. Specifically look for adults and mummified aphids.

Proper release techniques ensure Aphidius colemani establish quickly and begin controlling pests effectively:

1. Distribute the product: Release mummies evenly throughout the crop. A. colemani is very mobile and will fly around. Distribute the product evenly over the growing medium or place it into application boxes (Dibox) for release. Make sure the material remains dry and stays at its introduction site for a few days.
2. Recommended density: Release rates typically range from 0.25 to 4 adults per m², depending on crop type, infestation level and crop stage.
3. Follow‑up releases: In curative situations or severe infestations, multiple releases, every 7–14 days often improves establishment and control.
4. Avoid interference: Do not release immediately before or after broad‑spectrum insecticide applications. If treatments are needed, choose only those compatible with beneficial insects.

Tips for Selecting Rate:

• For dense crops, high pest pressure or curative use → choose a higher rate and repeat releases, weekly or bi-weekly (every 7-14 days).
• For preventive use in low‑pressure crops → choose a lower preventative rate, and watch for product establishment.
• Always match release strategy to crop size, foliage density, pest risk, and environment.

Visual checks: After 14-21 days from the first release, inspect leaves, flowers, and fruit clusters to determine if additional releases are required. Specifically look for adults and mummified aphids.

Supplemental releases: If aphid count remains high or increases, consider additional releases or review your IPM plan for gaps (e.g., residual pesticide effects, low humidity zones, new pest introduction).

Record‑keeping: Track release dates, environmental conditions, pest levels and predator observations to refine future programs.

What to Expect After Release:

• First week: Adult wasps begin parasitizing aphids.
• 2-3 weeks: Aphid mummies become visible, indicating successful parasitism.
• Ongoing: New adult wasps emerge from mummies, continuing aphid control across the crop.

Because parasitic wasps work biologically, control is progressive, not instant. Monitoring aphid levels and mummy formation is the best way to track success.

• Start releases early for best aphid suppression
• Focus monitoring on aphid mummies, not adult wasps
• Maintain suitable temperatures for optimal activity
• Combine with cultural controls like removing heavily infested plant material and other predatory insects like Chrysoperla carnea for instant control.
• Use as part of a balanced IPM strategy for long-term aphid management