Cambrians are all too familiar with the bark beetles that infect our pines with the dreaded pine pitch canker, but there is another “in your face” beetle we find equally frustrating. The tiny marauder invades our gardens in the spring, and stays throughout the summer, devouring our vegetation and, worst of all, our treasured flowers.
The Western Spotted Cucumber Beetle (Diabrotica undecimpunctata) is often mistaken for the beloved “ladybug” or “lady beetle” (Coccinella septempunctata). The two bugs are not related, although they are the same size and shape.
The ladybug is red with black spots. It’s considered a “beneficial insect” because it eats aphids and other unwelcome soft bodied sucking insects. Ladybugs lay eggs on the underside of leaves. Its larvae (a black and orange fuzzy creature) has an even greater appetite for “bad” bugs.
The cucumber beetle is green, or
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greenish yellow, with black spots. Unlike its “lady” look-alike, the cucumber beetle is no friend of the gardener. Instead of eating the aphids on roses, the cucumber beetle eats the rose blossom itself. It can devour an African daisy, a poppy, or a lily in a day. It loves anything yellow like squash blossoms, calendula, coreopsis, and most things green. The cucumber beetle has no predators, except birds.
There are few things you can do to “lessen” the impact these little insects have in your garden. Understanding their life cycle will help you to do this. Unlike the ladybug, the cucumber beetle can overwinter in the soil under plants. Fall clean up and
cultivating the soil around shrubs will help rid your garden of the hibernating beetles and their eggs in the soil.
In the larvae stage they actually chew on the roots of plants. After the hatch in early spring, you must go into full attack. In our climate, the adult beetles can create several generations during a season. Reducing the number of beetles early will help control the population.
Some organic methods of beetle control are:
• Patrol the garden in the early morning. Carry a small container of soapy water and knock bugs into the bucket;
• Spread onion or garlic skins on the soil around planted areas;
• Make a basin 3-inch deep around plants. Fill with wood ashes and moisten;
• Heavy mulching deters cucumber beetles from laying eggs in the ground; and
• Cultivate ground in the fall to expose the eggs.
Poison sprays will affect beneficial insects like bees and ladybugs, so I don’t recommend them.
I have seen damage decrease if I patrol with my trusty soapy bucket a few times a week. If nothing else, it gives me, lover of all living things, great satisfaction in knocking those annoying critters off my beautiful flowers and into their sudsy doom.