Insect Friends and Foes
It may come as a surprise to learn that not all insects are pests. In fact, a great many of them have a diet preference for harmful insects that cause damage to our landscape plants. Who could ask for better friends? Let's take a look at how to decide if we have an insect foe or friend in our garden and, also, how do we control the ones who do harm to our plants and cause us to grab a can of insect spray. Should our first reaction be to spray, spray, spray or are there other steps to take?
We should be routinely inspecting our plant for damage, looking for discoloration, unusual growth, swellings and leaf defoliation. The harmful insects can cause injury by chewing plants, sucking sap, boring into plants, eating roots or producing galls. Signs that insects may be the cause of the damage are caste skins, droppings, honeydew, froth, eggs and webbing. If we spot any of these signs, we should next check to see if any insects are still present on leaves, flowers or stems. If there aren't any, it won't do any good to use any type of a control.
However, if there are insects present, we should consider non-chemical physical measures as our first option. Some of these methods are: hand-picking, hard water spraying, insect traps, screens or netting. When non-chemical methods are not effective, and we have decided that the level of damage is not acceptable, we should choose the least toxic treatment that will effectively solve the problem. We should also be aware of what level of damage injures plants and which only affects appearance. Plants can generally tolerate insect feeding on leaves and flowers better than we can tolerate the imperfect appearance.
One of the easily recognizable and most familiar of the friendly insects is the ladybug. Many species have an enormous appetite for aphids, those little pear-shaped insects with green, black or orange coloring that damage plants by sucking out the sap and causing the plant to yellow and distort. A strong spray of water will knock the aphids off the plant.
The pale green, one-half inch to three-quarter inch insect with oval shaped, folded wings tilted above its body is a lacewing with a fondness for aphids, mites and whiteflies. The praying mantis, both nymphs and adults, lie in wait for an unlucky tidbit to cross its path. The lowly ground beetle, larvae and adults, feed on a variety of insects. The best known and best friend of gardeners everywhere is the honey bee, a pollinator; without them there would be no apples, berries, melons, cucumbers, squash or many other of our food crops. Never spray pesticides when bees are pollinating if we want to keep these friendly gardening partners around.
Birds, frogs, lizards, spiders and toads are also on our side in the battle against harmful insects. Birds are said to eat their full weight in insects each day. To encourage their presence in our yards, we could place birdhouses in the landscape and birdbaths in our garden.
Planting the following plants can also help to attract beneficial insects: yarrow, dill, cosmos, tansy, bee balm, chamomile, coneflower, lavender, rosemary, zinnia and thyme.
Betty J Magnan
Beltrami County Master Gardener
