Some folks need a reminder that one or two or even a dozen insects do not constitute an invasion, warranting a spray. “I saw a bug, what do I spray?” is an attitude we need to overcome. Remember, the destructive insects arrive first, and beneficial insects arrive only when there are a sufficient number of their prey to feed on.
If insects are few in number, pick them off by hand and drop them into a bucket of hot soapy water. Grasshoppers? Get to the garden early, when hoppers are slow moving and grab or decapitate them with pruners.
IPM is a good guide for gardeners. Those letters stand for Integrated Pest Management. It is a plan to control pests of all sorts while being kind to the land, our environment, humans, pets, and beneficial insects by interrupting the pests’ life cycles.
When you see destructive insects in your garden, assess how much damage they’re really doing. If they’re doing a little cosmetic damage, you need take no action. If they’re doing more than that, you should consider modifying your culture, such as application of more or less water, growing resistant varieties or erecting barriers to destructive insects. Carrot rust flies, for example, don’t or can’t fly very high, so a barrier of about 16 inches keeps them from your carrot crop. Floating row covers may help, but they may also bar pollinators. If you’re covering something like squash that depends on insect pollinators, you may have to do the pollinating yourself.
Or you could bring in beneficial insects or other creatures such as nematodes, poultry or even pet lizards or snakes. Planting flowering plants such as dill, parsley, lupines, bachelor’s buttons, phacelia, calendula, lavenders, mints, penstemons, yarrow, etc. works to lure and feed beneficial insects. You could even let your dandelions live. Beneficials love dandelions.
The Treasure Valley is home to a large number of newcomers, human and nonhuman, most of them welcome. A few bad apples have moved into our area, and they are not welcome here. Bad critters such as Japanese beetles, elm seed beetles, and walnut twig beetles have been with us for more than a year, but Japanese beetles top the list of “bad apples.”
Japanese beetles are so destructive the state is paying for control measures. They’re hiring a lawn care company to oversee application of granular pesticides on lawns in areas where Japanese beetles have been found. Some agencies such as Boise State University and Boise Parks will use their own maintenance crews. The first application will be Acelepryn, the second an imidacloprid (a neonicotinoid). The Idaho Department of Agriculture is working closely with homeowners so there’ll be no surprises when and where the pesticides are spread. After obtaining landowners’ permission, tags will be hung on doors a week before application.
Adult Japanese beetles can fly, so they’re more difficult to kill than the larvae that hatch after eggs are laid in turf. The larvae are obviously the intended target of the granular pesticides.
In 2012, 60 Japanese beetles were trapped, and in the following year 3,000. Last year 1,300, indicating some effectiveness of pest control. This year crews will treat 1,700 residential and commercial properties, most in the North End and at river level.
Walnut twig beetles carrying thousand cankers fungus disease, are killing black and English walnuts in this area. Elm seed beetles are more annoying to homeowners when they invade homes than they are destructive to elm trees.
Destructive insects tend to jump this region and invade the coastal regions of the Pacific Northwest before coming or being brought to our area. Brown marmorated stink bugs, spotted wing drosophila, red lily leaf beetle, viburnum leaf beetles, mountain ash sawfly, and other seed beetles are new invaders in Washington and Oregon. One of those stink bugs and one spotted wing drosophila have been found in Idaho so far, according to Dr. Paul Castrovillo, entomologist with the Idaho State Department of Agriculture.
Send garden questions to firstname.lastname@example.org or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.