Thursday, September 10, 2009

Battling Insects

Inali and I went for a walk this morning and came across an exterminator at a neighbor’s house. This always raises my hackles.

  1. How can people think that spraying chemicals to kill one kind of animal doesn’t have an unintended affect, in some way, on other animals, including humans?
  2. If they have to keep doing it on a regular basis, why don’t they question the usefulness of the practice?

Anyway, in this instance the bigger frustration was that emblazoned on the “we kill bugs” insignia was a green lacewing (Chrysoperla plorabunda).
This insect is an important predator species. As a juvenile it eats aphids and other insects.
This is an example of an insect you should encourage to live in your yard. You will not do that by spraying insecticide which kills

My neighbors right next door have an exterminator service that sprays all around their house every four months. (I know this because I stand at the side gate, making sure they do not spray into my yard.) The neighbors have been doing this for 15 years and they continue to have an ant and roach problem. And here’s the topper, their three grandchildren, all under the age of five, play in that sprayed grass.

Right next door, we do not have a problem.

Because of our tortoises we have never used sprays in our yard. For the first few years that we lived here we did put out ant bait in containers and snail pellets in the front yard. The pest species populations would ebb, but always return. Then we stopped completely to see what would happen.

We also started removing the water-hungry, exotic ornamental plants and replaced them with native plants. Our ant problem began to decline. The ants that cause problems all along coastal California are an invasive species, Argentine ants (Iridomyrmex humilis). Our native plants are less willing to give away sweet sap to insects. They have tough waxy coverings or hairs that thwart Argentine ants. This South American ant species also requires water. Routine shallow watering provides the perfect habitat for them to thrive. They don’t create deep nests, they stay close to the surface. A dripping faucet beside a stepping stone is their idea of paradise. Reduce that regular watering, fix leaky plumbing, and it becomes harder for them to make a living.

I do still have ornamental roses, but if my roses are insecticide free the green lacewings and the lady bugs, as well as the bushtits and wrens keep the insect population to a minimum.

When you build a house, you are building it on land where other creatures lived before you. Like any landowner, they will try to reestablish their right of ownership. Other insects will come if habitat is offered. If you create a water-dependent English garden in a southern California Mediterranean climate, you are creating an oasis for invasive exotic pest species.

Native plants are just as beautiful and native insects have predator species that keep them in check without my lifting a finger.

So stop spraying and the next time you see a green lacewing thank it for the job it does in your garden.

1 comment:

Wild Flora said...

One of my native elders was covered in black aphids earlier this year. Within a couple of weeks, the predatory insects including lady beetles soon showed up, along with small birds that prey on aphids. The aphids were completely gone a couple of months later. The shrub bloomed normally and produced a big crop of berries, much appreciated by flock of thrushes. All of which is just to say that you're absolutely right--most insect infestations will right themselves if nature is given a chance to work. Thanks for reminding your readers of this.