Everywhere that I’ve lived, there has been at least one insect that I find especially annoying. In Marin and Sonoma Counties I despised the yellow jacket, often called “meat bees”. Those little monsters, similar in appearance to the sweet honeybee, would spoil every picnic we had and sting us for no apparent reason. Yellow jackets, a member of the wasp family, are beneficial in that are scavengers, eating rotting meat and decaying fruit but humans beware! They can ruin and bar-b-que in minutes.
In San Luis County, the most annoying of pests to local gardeners is the innocent looking spotted beetle but that looks like a green ladybug. The Western Spotted Cucumber Beetle (Diabrotica undecimpunctata) is often mistaken for our 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 is considered a “beneficial insect” because it eats aphids and other unwelcome soft-bodied sucking insects. Ladybugs lay eggs on the underside of leaves. Their larvae (a black and orange fuzzy creature) has an even greater appetite for “bad” bugs. Be sure you are careful with spraying and “let these critters do their job”.
The dreaded spotted cucumber beetle is green, or greenish-yellow, with black spots. Unlike its “lady” look-alike, the cucumber beetle has no redeeming qualities. 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 a few things you can do to “lessen” the impact that these little insect 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. Cleaning up in the fall and cultivating the soil around trees and shrubs will help rid your garden of the hibernating beetles and their eggs. In the larvae stage they chew on the underground roots of plants. When they 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″ deep around plants. Fill with wood ashes and moisten.
- Heavy mulching deters cucumber beetles from laying eggs in the ground.
- Cultivate the 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. When I see a cucumber beetle, I tap the flower or leaf it is sitting on and it falls into the soapy water below. It gives me, ordinarily a lover of all living things, great satisfaction in knocking those annoying critters off my beautiful flowers and into their sudsy doom.