# Grape erineum mite

- URL: https://backyardgrapes.com/diseases/grape-erineum-mite/
- Scientific name: Colomerus vitis
- Category: Insect / pest
- Affects: Leaves
- Severity: low
- Favored by: Overwinters under bud scales; most visible in spring on new growth; found worldwide.
- Easily confused with: Downy mildew, Spider mites

**Summary:** A microscopic blister mite that raises fuzzy welts on leaves — alarming but rarely harmful.

**What to look for:**
- Raised blisters or bumps on the upper leaf surface.
- Dense, felty white-to-tan hair (the "erineum") in matching patches on the underside.
- Patches later turn reddish-brown; young leaves may look puckered or distorted.
- Vigour and yield are almost never affected.

**Treatment — Cultural / prevention:**
- Usually cosmetic — no action is needed on established vines.
- Pick off the worst leaves early in the season if the look bothers you.

**Treatment — Organic / low-toxicity:**
- For heavy cases on young vines, sulphur or horticultural oil at bud swell.

**Treatment — Conventional (chemical):**
- Rarely warranted; specific miticides only if damage is genuinely severe.

The grape erineum mite is a microscopic relative of spider mites that causes one of the
most commonly misidentified symptoms in the vineyard. Its feeding makes the leaf grow
blisters on top and a dense mat of felty hairs beneath — white or tan at first, then
rusty red. Growers often mistake the fuzzy underside patches for downy mildew, but downy
mildew's growth wipes off and sits under yellow "oil spots", while the erineum is a firm,
felt-like mat of leaf hairs that won't rub away.

The reassuring news is that it almost never matters. The mite disfigures leaves but rarely
affects the vine's health or crop, so on an established vine the right response is usually
to do nothing. Only heavy infestations on young vines justify a sulphur or oil spray at
bud swell.

**Image credits:**
- Grape erineum mite (Colomerus vitis) galls, leaf underside and upper side — [Photo: Olivier Lemoine (Photo-Terroir.fr), Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Erinose_de_la_vigne,_vue_de_dessous-dessus.jpg) (CC BY-SA 4.0)
- Erineum mite damage on home garden grape leaves: blisters on top, concave areas beneath filled with white felt-like enlarged leaf hairs — [Photo: J.R. Natter, OSU Extension Service Metro-area Master Gardener Newsletter](https://blogs.oregonstate.edu/mgmetro/2018/07/01/blister-mites-grapes-pears-walnuts/)
- Grape leaf blister mite damage on a grapevine leaf — [Barmac (Amgrow)](https://barmac.com.au/problem/grape-leaf-blister-mite/)

**Sources:**
- [Grape Erineum Mite](https://ipm.ucanr.edu/home-and-landscape/grape-erineum-mite/) — UC IPM
- [Grape: Grape erineum mite](https://hortsense.cahnrs.wsu.edu/fact-sheet/grape-grape-erineum-mite/) — Washington State University Extension (Hortsense)
- [Grape-Grape erineum mite](https://pnwhandbooks.org/insect/small-fruit/grape/grape-grape-erineum-mite) — Pacific Northwest Pest Management Handbooks (OSU / WSU / U. Idaho)