The tent caterpillars seem to be back again, for yet another year! They can be quite destructive as they eat the foliage off many of the deciduous trees and shrubs.

They don't actually kill the tree but they put a lot of stress on the tree as they strip the tree of all its foliage. The tree then has to put out more energy to create new foliage. A tree can do this for one or two years but it will die eventually, as it takes too much energy away from the tree to continually produce a second set of foliage.

To prevent too much damage you want to quickly destroy the caterpillars.

Ideally it would be best to find the eggs and destroy them before they ever get a chance to hatch. The eggs are in hard grey/brown bands that encircle the branches of deciduous trees and shrubs.

Applying 'Lime sulphur and Dormant Oil' in early spring before the tree/shrub breaks into leave would destroy many of the eggs. It is now too late to do that, as most trees and shrubs are already in leaf.

The next best thing would be to find the caterpillars as they begin to hatch, which is what is happening now. As the caterpillars hatch, they are in one concentrated area, which makes it easy to find them and destroy them. They will eat the foliage and when its gone they will move to find more foliage.

If you do not have caterpillars on your trees but know that they may be in the area, you can stop them from climbing up your trees by putting 'Tree Tanglefoot' around the trunk of the tree. Tree Tanglefoot is an easy to use product available at the garden centres. It is simply a sticky substance that is placed on a 10 cm wide strip of waterproof paper that has been wrapped around the trunk of the tree. As the caterpillars try to crawl up the tree they will get stuck in the Tanglefoot preventing them from going any further. When the Tanglefoot covered paper is full of caterpillars, remove it from the tree and replace it with a new one. This will prevent any other caterpillars from crawling over the stuck caterpillars to get up the tree.

If the caterpillars are already in the tree, you can either try to handpick them off the tree or go to a chemical way of destroying them. There is an organic product available called 'BTK' put out by 'Safers'. It is not harmful to other insects or birds. BTK is sprayed on the foliage of the tree/shrub, following the manufacturers instructions and when the caterpillar ingests the treated foliage it will stop eating and will die in a few days.

There are other products available that will instantly kill the caterpillars. These products must be used cautiously and not applied to trees/shrubs that are in bloom. These products include 'Malathion', 'Ambush' and 'Sevin'. They are very effective when used following the manufacturer’s instructions.

-Jos

Jos Van Hage owns and operates two Art Knapp Home and Garden Centres in Prince George:

• Highway 16 West at Kimball Road
• Highway 97 North at Northwood Pulpmill Road