Gather 'round. It's time to talk about Tanglefoot paste and Mosquito Dunks

Each week, Susan Richards of New North Greenhouses answers your gardening questions. Have questions about your gardening needs? Please email her at [email protected]

Julie: Good morning, I picked up Btk insecticide for the tent caterpillar control and the dial-a-spray applicator but I'm unsure how to mix it even after reading the instructions. Can you help please?

Julie is referring to the biological control for the tent caterpillar infestation. Btk is a bacteria solution you spray onto the leaves of the trees and shrubs that the young caterpillars are eating. (See this link for more information)

Btk is a concentrate that is diluted with water before being applied. The mixing rate is 30 ml of concentrate added to 10 litres of water. For small plants, you can add 3 ml (a bit more than 1/2 tsp) in a litre of water.

For larger trees, use a hose end sprayer that attaches to a regular garden hose. This type of spray bottle has a dial on the top with numbers that represent a mixing rate measured in millilitres of concentrate per litre of water. Therefore set the dial at 3 to achieve the correct dilution rate.

Be sure to spray at a calm time and avoid the hottest time of the day.

You can also scrape off large 'nests' of caterpillars and drop them into a pail of soapy water. Branches with the tents can be pruned off and burned.

Paul: I have an infestation of tent caterpillars on my property that I want to stop from migrating to my mature trees. The trees are way too big to spray. How do I stop the caterpillars from getting into the trees?

You can put a barrier around the tree trunk and coat it with Tanglefoot paste. This very sticky substance will trap the caterpillars, preventing them from getting up into your trees. It's very important that you don't apply any of this or any other product you use, such as Vaseline, directly to the tree trunk. This will damage the bark.

First wrap tin foil or tar paper around the tree trunk and then apply the paste. If the tree bark is quite ridged, preventing you from getting a good seal with the barrier, apply a tight layer of batting first and then the tinfoil. The batting will fill the crevices making a good seal.

As soon as the infestation is over, be sure to remove the banding. If left on too long, bark may be damaged.

Susie: Mosquitoes are such a problem right now that I want to prevent them from laying eggs in my pond and birdbath. What can I do?

Btk is available in a donut shaped brick called Mosquito Dunks  that can be added to any area of standing water. The bacteria targets the larvae of the mosquito so is safe for aquatic life and birds.

Also, mosquitoes can't land to lay eggs in moving water, so fountain and pond pumps moving the water helps too. Fish in ponds will also eat mosquito larvae.