Spongy Moth

Outbreaks of Spongy moth occur every 7 to 10 years, and southern Ontario has been in one since 2019.

On behalf of our members in affected areas, FOCA has hosted webinars with industry experts about the life cycle and management of this pest. Members are invited to login below for access to the webinar slides.

Lymantria dispar dispar (LDD) or “Spongy moth” (formerly known as gypsy moth) is a forest defoliating insect found in Ontario.


The moths lay egg masses on trees, and the resulting young caterpillars that are born the following year feed on and defoliate the trees. Populations build and decline and eventually collapse. According to the Ontario Ministry of Natural Resources and Forestry (MNRF), outbreaks usually last 3 to 5 years.

The province of Ontario posts information here, including the life cycle of the pest.

May 2022 – If your property was affected by Spongy moth last year, it’s time to start wrapping your trees, and disposing of the remaining egg masses and larvae. For the map at the side, of deforestation in Ontario in 2021, click here and scroll down the page.

The following information is available to FOCA Members and Annual Supporters. Need help with your login? Contact us! Not yet a Member or Annual Supporter? Find out why you should be!

Please note: the following is archival material, and some links to third-party resources may no longer be active.

December 1, 2021 – Ontario Woodlot Association LDD / Gypsy moth webinar – a look back at 2021, and a 2022 outlook

November 14, 2021 – What invasive gypsy moth caterpillars are doing to our lakes and streams (CTVNews)

Oct 27, 2021 – Moth infestation tripled in 2021, with eastern Ontario bearing the brunt – “They’ve been moving eastward toward Ottawa, Carleton Place and Pakenham.” (Ottawa Citizen)

August 31, 2021 – Hastings County asking for help to track LDD infestations (Hastings County)

July 2021 – see additional resources posted by the Environment Council for Clear, Ston(e)y and White Lakes

June 23, 2021 – as reported by the Ontario Woodlot on Twitter“A member reports that the virus and fungus are taking hold. The photo shows the classic fungus (left) and virus (right) effects.” [see image at the side]

May 22, 2021 – Gypsy moth caterpillars ‘virtually everywhere’ in SW Ontario, expert says (CBC.ca)

May 3, 2021 – Town of Oakville to conduct aerial spraying to combat gypsy moths (Toronto Star)

April 2021 – Gypsy Moth Information from the Regional Forest Health Network (Southern Ontario)

July 22, 2020 – How Ontario is battling a very hungry caterpillar (TVO) – Gypsy-moth caterpillars are killing trees throughout the province.

July 15, 2020 – Eastern Ontario in grip of worst Gypsy moth outbreak in 30 years (Belleville Intelligencer)

July 9, 2020 – Forests in Peterborough and the Kawarthas are under attack (Peterborough Examiner)