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BeneficialBrown marmorated stink bug

Samurai wasp and brown marmorated stink bug

Trissolcus japonicus · wild egg parasitoid (not sold)
Against brown marmorated stink bug

The samurai wasp is a key natural enemy of the brown marmorated stink bug and the main candidate for its biological control: it lays its eggs inside the stink bug's eggs, usually attacking the whole mass, and in Asia kills up to 80% (Cornell) or 60–90% (StopBMSB) of the eggs. It is not sold, and the releases so far have been made by researchers within their own states. A gardener's part is to conserve it: leave dark grey or black egg masses on the leaf, since they are parasitised and will release more wasps, crush only pale green masses, and avoid broad-spectrum sprays, to which the wasp is very susceptible.

RateWild — conserve; not for release (not sold; interstate movement restricted)
TimingWhenever egg masses are on the leaves; parasitised masses turn dark within about a week
macro · samurai wasp on brown marmorated stink bug
The pestBrown marmorated stink bugHalyomorpha halysSunken white or yellow blotches on tomato and pepper, scarred and misshapen fruit; crowds in the house every autumnFull pest profile →

Before you act

A shiny black wasp 1–2 mm long that lays its eggs inside brown marmorated stink bug eggs. It arrived in the US on its own and is spreading. It is not sold. Conserve it by leaving darkened egg masses on the leaf. How to recognise it, what it is confused with and how to keep it around are on the full Samurai wasp profile.

Other controls for brown marmorated stink bug