Insect management in Winter

The allies of your garden such as ladybugs, syrphid flies, ground beetles and parasitic wasps will stick close to a successful environment. We want to encourage their presence. When you are implementing controls of any kind the aim should be BALANCE not elimination. Balance is achieved through diversity and established thresholds. Diversity means having a broad spectrum of plant variety and insect species.

Thresholds are a predetermined level of pests that we can manage without severely impacting a crop .For example; a low level of aphids is necessary to keep the ladybugs and other aphid predators active in your garden. We need to conduct our garden cleanup with this in mind, approaching the activity with all aspects of the natural system considered.

Follow these guidelines to ensure that you are addressing the problem while not eliminating your allies in the garden.

  • Leave healthy, standing, hollow stemmed plants as refuge spots for ladybugs and solitary bees.
  • Rocks and logs strategically placed in the garden for aesthetic effect make excellent refuge for predatory beetles.
  • Wait until Spring to cut back ornamental grasses. These perennials are ideal locations for overwintering bumblebees.
  • Create small piles of maple leaves, brush or untreated grass clippings for ground beetles and other terrestrial predators.
    Add fresh compost to beds to boost beneficial microbes and predatory mites.

Winter Control Guidelines For Pest Control:

  • Inspect and remove plant material in the garden where known pests existed. Check the leaves of kale, cabbages and brussel sprouts for aphids. If found, remove material and dispose into garbage. Not in compost pile.
  • In asparagus patches, remove remaining plant debris where asparagus beetle or aphids are overwintering.
  • Turn the soil lightly to expose any soil dwelling cutworms, potato beetle and grubs to the birds. You can even go so far as to scatter bird seed to encourage types that eat both insects and seed.
  • Collect any beetles and gently transport them to the composter and place under the material.
  • Clean greenhouse structure with mild bleach solution to kill any fungus spores. If structure is wood follow up bleach solution with horticultural oil painted onto all exposed wood. This will suffocate the spidermite, thrips and other tiny pests who are hibernating in the cracks and crevices.

Beneficial insects use rough vegetation to either overwinter themselves or lay eggs to be hatched next spring. Those eggs will hatch before aphids and other pests appear. The adults from this first round of eggs will lay their eggs in time to control the aphids then later on thrips, spider mites etc.

By cutting back all that rough vegetation now you are essentially tossing nature’s army of beneficial insects into the trash and that’s a waste of their talent. This is all part of creating a “host environment”

Another reason not to cut back the vegetation is that many of the flower heads contain seeds that birds can overwinter on. It’s the same reason I advise to stop deadheading your roses in early Winter so they can set hips. Hips are those “berries” that appear when the flowers fall off naturally. They are a great food source for many animals.

Try to resist the urge to cut back your garden over winter. I know it’s nice to have it looking tidy during the winter but just think forward to next spring when possibly cutting it back now could result in an aphid infestation later. In my opinion that would be much worse!

When Spring arrives and the first of the plants start to bloom, get out there and have a look around. The more you know the better equipped you will be. Check for plants that are struggling, these will be the first to be hit by pests. Notice which plants are thriving. What is it that makes them so successful? Learn which insects inhabit your garden to determine what you may be missing and take the steps to encourage the missing ones in.