Margaret Lauterbach

Make good use of beneficial insects to make sure your garden thrives

Ladybugs are beneficial insects that can help your garden.
Ladybugs are beneficial insects that can help your garden. AP file

Gardeners have three main problems: failure of seeds to germinate or plants to thrive; weeds; and insects. If your seeds don’t germinate and they’re fresh, put some in a resealable storage bag with a bit of potting soil and put it in the refrigerator for a week; then replant. Sometimes this works, but not always. If your seed does germinate, watch out for damping off, a fungus that causes failure of circulatory system in tiny seedlings, and they dimple in at soil line and fall over dead.

Make sure your seedlings have good circulation, and if you don’t bottom-water them (soak pots in a tub), spritz only with chamomile tea (three bags to a quart or two of boiling water). Cool this tea before watering seedlings to prevent damping off. Once the fungus attacks, nothing can save seedlings. Don’t transplant them out until soil is about 60 degrees.

Use a scuffle hoe or hand scraper to cut tiny leaves off weeds. Scraping the soil free of weeds is a lot easier than waiting until they’re so large that you must pull or chop them. Once soil is bare, use organic mulch to cover it. Only perennial weeds will come up through mulch, and annual weeds won’t take root.

The insect problem can be greatly eased if you are able to attract and keep beneficial insects in or near your garden, for they’re better than any gardener at spotting newly hatched destructive larvae. It is true that for those beneficial insects that consume their prey, they usually leave a few living specimens to provide their next or future meals, but that won’t cause major problems for you.

Also, the beneficial insects may not show up until there’s enough for a pigging-out banquet of prey. Just be patient, gardeners, and the beneficials will show up. Lady beetles, or ladybugs, overwinter in our Foothills and return to the valley in early summer. They’ll be of enormous help if you don’t kill them off with residual pesticides such as diatomaceous earth, BT or Sevin dust (or any worse pesticide dust) that waits for insects to show up, killing them when they arrive. If an infestation of aphids, for example, is worse than you can tolerate while you wait for beneficial insect help, use your garden hose to blast aphids off your plants. The few black aphids in a population can fly, but the green ones cannot. They’d have to walk back to the plant and climb it, but they’re more likely to die before they get there. Beneficials can survive water.

Beneficial insect adults are attracted by blossoms with shallow nectar sources, such as dandelions, or dill, parsley, mint or fennel flowers. It can be tricky to sow plants that will bloom in a summerlong series. Beneficial insects, like all creatures, also need a water source, and that may be droplets on leaves (even soaker hoses get a little water on the leaves, a good reason to water in morning so leaves can dry off before evening cool sets in), or a saucer with pebbles and water. Water on foliage, especially in falling temperatures, is an invitation to disease.

Consider mint in the garden. You don’t want it in garden beds, for it spreads aggressively and takes over, but its blossoms are extremely attractive to tiny beneficial insects. But you can place pots of it in the garden, picking them up and turning them often so they don’t sneak rhizomes out of the drainage hole and begin infesting your bed. Proximity of mint seemed to repel squash bugs in my garden last year, and the strong odor may repel other destructive critters.

Beneficial insects include ladybugs, green/brown lacewings, praying mantises, hover flies (they look like bees), big-eyed bugs, assassin bugs, minute pirate bugs, and tiny beneficial (nonstinging) wasps such as Encarsia formosa and Trichogramma. They exist naturally in this area; it’s just the gardener’s job to attract and keep them around.

Larvae of ladybugs, and those of green lace wings (and brown lace wings), look like tiny alligators, with soft brown coats (ladybugs have orange spots, too). They are the biggest gobblers of aphids, whiteflies and other tiny insects in your garden. Another helper, especially early in summer, are the mud and paper nest wasps or hornets. They lick up aphids, feeding themselves, and patrol your garden for newly hatched destructive larvae. Wasps can detect those larvae faster than I. I haven’t had a larva in broccoli for many years, nor a hornworm on tomatoes. I found a little hornworm damage about two years ago (and saw its bedraggled huge moth mother taking her last gasp), but never saw the hornworm, so I presume a wasp or bird had feasted on the tiny hornworm.

Incidentally, green lacewings somehow lay eggs on the tops of hairlike posts, one egg per hair, so if you happen to see a series of hairs rising over an inch in height from a twig or leaf in your garden, marvel and treasure it. When eggs hatch, the lacewing larvae must just fall to the leaf their stalk was on. Ladybug eggs are yellow, oval (standing on end) and laid in groups. Squash bug eggs are more orange and round. Do not destroy the former eggs.

Syrphid or hover fly eggs are laid singly near aphid colonies, and look like white rice, with very tiny ridges. Their maggots are at least partly translucent, smaller at the head end than at the other end. Adults look a lot like bees that hover.

Send garden questions to or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.