TORONTO - A new insecticide has been approved for use in Ontario to combat the spread of the invasive emerald ash borer, which has killed more than 20 million ash trees in North America.

The Ontario government says TreeAzin is based on an ingredient extracted from the neem tree of India and is environmentally safe.

When injected into the trunk of a tree, it inhibits the growth of larvae and prevents the emergence of adult emerald ash borers.

Ontario's Natural Resources Ministry received approval from Health Canada and the province's Environment Ministry following research trials.

Developed in Burlington and Sault Ste. Marie, the insecticide is available through BioForest Technologies Inc. and tree-care companies.

The emerald ash borer has been found in Essex County, Chatham-Kent, Lambton County, Elgin County, Middlesex County, Norfolk County and Toronto.

"This product will be an important new tool in our ongoing fight to control the spread of destructive forest pests and protect the health of Ontario trees,'' Natural Resources Minister Donna Cansfield said in a release.

The insect was first found in North America in June 2002 in Michigan and shortly after in Windsor, Ont.

The emerald ash borer can kill healthy ash trees in only one to two years as the larvae create tunnels by feeding under the bark of trees, preventing the flow of nutrients.