Invasive Species
Learn about the invasive species that weaken and destroy our urban forests within the City of St. Catharines. Find out how to control and reduce the invasive species including Spongy Moth and Emerald Ash Borer.
What are Spongy Moths?
The Spongy Moth (Lymantria dispar), previously known as European Gypsy Month, is an insect that can severely weaken or kill trees by eating all the leaves during its caterpillar or larva stage. This makes them more susceptible to disease and damage from other insects.
What does a Spongy Moth look like?
There are four stages of a Spongy Moth which changes their look:
- Stage one – egg
- Stage two – caterpillar (very distinctive blue and red spots)
- Stage three – pupa
- Sage four – moth
Where do Spongy Moths live?
Spongy moths are preferred hosts to:
- Oak
- Birch
- Poplar
- Willow
- Beech
- Cherry
- Maple
- Apple
- Basswood
- Elm
Spongy Moths are less commonly found on:
- Ash
- Catapla
- Horse chestnut
- Locust
- London plane
- Coniferous trees
How to control Spongy Moths
There are a variety of ways to control Spongy Moths from destroying your trees. These methods include:
- Remove and destroy egg masses wherever you find them reduce the number of caterpillars for the coming season
- Wrap a piece of burlap cloth around tree stems folding the band to provide caterpillars with a hiding place from the heat of the day, then collect and destroy caterpillars from this shelter each afternoon
- Trap male moths by hanging pheromone (sex hormone) traps on the trees to act as decoys and prevent male moths from mating with female moths
- Attract birds to your yard so they can eat the moths by planting herbs, flowers and shrubs
How do I control a severe case of Spongy Moths?
If your trees have a severe case of Spongy Moths, apply a biological insecticide containing Bacillus thuringiensis kurstaki (Btk). This bacterial insecticide affects the caterpillars of moths and butterflies. It is only effective when caterpillars are in an early stage of development. Apply treatment as soon as feeding begins. A good indicator of the correct time to apply Btk is when Bridal wreath Spirea is in bloom.
How to maintain your tree's health
If you have Spongy Moths, continue to maintain your tree's health by:
- Water your trees during dry spells
- Place organic mulch (i.e. wood chips), or living mulch (i.e. ground cover plants) around tree bases to keep the soil moist for longer periods and encourage healthier roots
- Avoid unnecessary excavating, grade changes, soil compaction, root cutting or hard surfacing around trees
- Refrain from using salt or herbicides around trees
What is Emerald Ash Borer?
The Emerald Ash Borer (EAB) is a pest introduced from Asia that affects all species of Ash trees in North America. EAB has killed millions of Ash trees across southern Ontario and North America.
How are Emerald Ash Borer invasive?
Emerald Ash Borer infest trees when the beetle lays its eggs on the bark and in bark crevices on the trunk and branches. The larvae then tunnel beneath the bark and feed on the layer of live cells between the bark and the sapwood, cutting off the transport of nutrients and water to the tree. Although a tree may have some signs of EAB infestation, other diseases or infestations may be affecting the trees growth.
Trees can die from EAB infestation within two to three years of a tree or as short as one year.
How to identify EAB
Identify Ash trees and EAB infestation with help from this EAB Identification Guide.
Report an Ash tree with EAB
If you see an Ash tree on City property showing signs of EAB contact Forestry Services at 905.935.3813.
How to treat EAB on your trees
If you have an EAB infestation on your trees, contact a private certified arborist to do an inspection. The arborist will be able to confirm the presence of EAB and recommend treatment options.
How to limit the spread of EAB
We encourage you to treat your Ash trees and limit the movement of firewood wherever possible to help contain the spread of EAB.
How the City manages EAB
The EAB has been found within the city and all Ash trees in St. Catharines are at risk of dying from infestation. As a result, the City is implementing an EAB management program which includes treatment of viable Ash trees, and removal and replacement of non-viable trees where appropriate.
Learn more about EABs
Find additional resources on Emerald Ash Borer including: