Pest profile

Aphid Parasitoid Wasps

Aphidiinae (Aphidius, Lysiphlebus and relatives) · Hymenoptera: Braconidae[5]

If you see swollen, crusty tan aphids glued to a leaf, a tiny parasitic wasp has killed them from the inside. These aphid mummies mean natural control is under way.[1][2]

Tan, puffy aphid mummies stuck to a green stem, one with a round hole where the adult parasitic wasp chewed its way out
Tan, puffy aphid mummies stuck to a green stem, one with a round hole where the adult parasitic wasp chewed its way out. (c) Gianni Del Bufalo bygdb, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Parasitized aphids become crusty, puffy, smooth mummies colored brown, gold or tan.[1][2]
  • A round hole in a mummy shows where the adult wasp chewed out.[1][2]
  • Adults are slender wasps 1/8 inch or less, with long, thin antennae; Lysiphlebus testaceipes is black and about 1/12 inch.[1][2]
  • A parasitized aphid looks normal for about a week, so more aphids may be parasitized than you can see.[1]

Look-alikes

Look-alikeHow to tell them apart
Aphids killed by aphelinid waspsAphids parasitized by wasps in the family Aphelinidae turn black instead of tan.[1][2]
Healthy aphidsUnparasitized aphids are soft, have no holes and keep their species' normal color.[1]

Where it lives

Lysiphlebus testaceipes occurs throughout the United States and is often the most abundant aphid parasitoid. More than a dozen Aphidius species live in California alone.[2][1]

US map: public records from 13 states since 1990 (GBIF).

Biology and life cycle

The female lays one egg inside an aphid, and the wasp larva feeds within it.[1][2]

About a week to 10 days later the larva kills the aphid, glues it to the leaf and pupates inside the mummy.[1][2]

Egg to adult takes about two weeks in summer, with several generations a year.[1][2]

Parasitized aphids stop reproducing within one to five days, which slows the colony even before mummies show.[3]

Damage and signs

  • Each Aphidius female lays eggs in about 100 aphids, and Lysiphlebus testaceipes attacks over 100 aphid species.[1][2]
  • Lysiphlebus adults are inactive below about 56 degrees F, so they may control aphids poorly in cool spring and fall weather.[3]

Health risk

Parasitoid wasps, aphid parasitoids included, do not sting people.[4]

Control

Biological control

Hold off on spraying when mummies are common; in Cornell's greenbug example, an infestation usually declines fast once 20 percent are mummies.[3]

Control ants, which attack natural enemies, and grow flowering plants that give adult wasps nectar.[1][2]

Some Aphidius species are sold for release against aphids in greenhouses and crops.[1]

Common questions

What are the brown, puffy aphids on my plants?
They're aphid mummies: aphids killed by a parasitic wasp that is pupating, or already gone, inside.[1][2]
Should I wash the mummies off?
Leave them. Each intact mummy holds a wasp that will emerge and attack more aphids.[2][3]
Do these wasps sting?
No. Parasitoid wasps do not sting people.[4]

Sources

  1. University of California Statewide IPM Program, “Aphid Aphidius Parasitoids (Natural Enemies Gallery).” ipm.ucanr.edu/natural-enemies/aphid-aphidius-parasitoids/ (accessed 2026-10-06)
  2. University of California Statewide IPM Program, “Aphid Lysiphlebus Parasitoid (Natural Enemies Gallery).” ipm.ucanr.edu/natural-enemies/aphid-lysiphlebus-parasitoid/ (accessed 2026-10-06)
  3. Cornell University College of Agriculture and Life Sciences, “Biological Control: A Guide to Natural Enemies in North America: Lysiphlebus testaceipes.” biocontrol.entomology.cornell.edu/parasitoids/lysiphlebus.php (accessed 2026-10-06)
  4. University of Maryland Extension, “Parasitoid wasps.” extension.umd.edu/resource/parasitoid-wasps (accessed 2026-10-06)
  5. iNaturalist, “Aphidiinae taxon page (order and family).” www.inaturalist.org/taxa/354557 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.