Creature Feature: Nesi — The Green Bug That’s Not Always Good News

Authors: Julia Dubeau (Research Assistant, OMAFA), Rose Labbé, PhD (Research Scientist, Greenhouse Entomology, AAFC), and Cara McCreary (Greenhouse Vegetable IPM Specialist, OMAFA)

Meet the Creature

For this Creature Feature, we’re meeting Nesidiocoris tenuis, commonly known as Nesi, green bug, or tomato bug.

Close-up of a green late-instar Nesi nymph with developing wing buds

Nesi is a small green mirid bug that has become a concern for Ontario greenhouse vegetable growers – specifically greenhouse tomatoes and greenhouse cucumbers but greenhouse peppers are also a potential host.

At first glance, Nesi might not look too scary. It is small, green, and easy to mistake for something helpful. But this is one of those “don’t judge a bug by its colour” situations — not every green bug in the crop is a good bug!

Nesi is an omnivorous mirid, meaning it can feed on both insects and plant tissue. In some regions around the world, it has been used as a beneficial insect, but in Ontario greenhouse vegetable production it is considered a pest because of the plant damage it can cause.

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Mirid Identification Resources

Below you will find details to assist with identifying some key mirid species. The focus is distinguishing between Dicyphus hesperus, a beneficial mirid, and Nesidiocoris tenuis, a pest mirid. This material was presented in the Tools of the Trade Workshop at the 2025 Canadian Greenhouse Conference.

These PDF’s can be downloaded and used as reference material. They can be printed on letter size paper.

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