The garden's infested. A morning walk finds translucent aphids gathered on my rosebuds and on the tops of euphorbia leaves. What's going to eat...
The garden’s infested.
A morning walk finds translucent aphids gathered on my rosebuds and on the tops of euphorbia leaves. What’s going to eat these?
Going green in the garden means close observation, getting acquainted with the beneficial insects and watching them help out the garden ecosystem.
All landscapes hold varieties of garden helpers, including wasps, spiders, beetles and birds, and many more we don’t see easily. Every garden’s a complex unity; the more complicated, the better.
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To be sure you’re treating your seen and unseen beneficial bugs properly, take a few simple steps:
Attracting beneficial bugs
• Keep shallow bowls of water handy, filled daily. (An old glass pie pan or shallow casserole lid works well.) You’ll notice wasps and other insects taking water throughout the summer.
• Plant a variety of blooming flowers. Ladybugs (convergent lady beetles) primarily eat aphids and other small insects but are attracted to nectar. Plants with umbrella-shaped flowers attract them and their prey: caraway, cilantro, Angelica and dill flowers will bring insects into the garden.
• Allow some aphids to build up. Insects need food and prey; a few aphids won’t kill a rose, and they will feed beneficial insects as well as birds. Aphids are a fine protein-packed meal (a ladybug’s power bar?).
• Renounce pesticides. Obviously, spraying an insect-killer will wipe out the good guys as well as the damaging ones. Even fungicides and weedkillers can be harmful to insects. Insect-killers may be hiding in fertilizers: A common rose fertilizer also contains a systemic insecticide called disulfoton. Check labels before buying.
• Learn to identify the larval form of the ladybug. These gold-and-black alligator-shaped larvae hatch from small yellow barrel-shaped eggs laid by the female adult, usually on or under a leaf near prey. The larvae arrive hungry and eat even more than their parents. Now and then people gather the larvae, thinking they are dangerous. One misinformed person brought 57 of them into the Washington State University/King County Cooperative Extension office in a bottle, saying, “These are all over my plants.”
• Enjoy observing garden plants: The more you look, the more you’ll see.
Buying beneficial bugs
What about purchasing beneficial insects to help out the garden? Ladybugs are the most commonly available, though praying-mantis eggs may be sold in spring. (Mantises will munch each other if there is no other food around.)
Mail-order sources will have a wider availability of types, including lacewings and some predatory wasps, often used inside greenhouses as well as outside in gardens.
Do be sure you’ve done all the steps above before bringing home a bag of live ladybugs. The most important need for them is prey: No food, no life for the ladybugs. If you don’t see an aphid infestation, skip the ladybug buy.
Bags of ladybugs will be refrigerated when sold; a common size contains 1,200 insects and sells for under $10. A random check of Seattle-area nurseries found them readily available at Molbak’s, Swansons and Sky Nursery. They’re gathered in Oregon when swarming in spring, and are usually carried April through October.
For best results, release the ladybugs in the evening, after sunset. Spray the foliage lightly where you see ladybug food such as aphids; they need water when released. Some people recommend placing a light sheet of cloth over the plants, then letting the ladybugs go free under it. If you cannot release them soon after purchase, refrigerate.
Ladybugs will fly off if they find no prey. They tend to fly when released in any case, so do not expect them all to sit down and stick around. People have varying results with them. The goal is to have enough ladybugs stay put and mate to produce a new generation for your garden.
Once born on site, ladybugs are more likely to set up a permanent colony. Females can produce 200 to 1,000 eggs that, given good conditions, will hatch into small hungry larvae that eat vigorously for 10 to 30 days before forming pupae.
Beneficial insects can’t help you unless you help them. Enjoy getting to know these critters!
Garden expert Mary Robson, retired area horticulture agent for Washington State University/King County Cooperative Extension, appears regularly in digs and in Practical Gardener in Northwest Life on Wednesdays. Her e-mail is firstname.lastname@example.org.