Bugs-B-Gone: A guide to natural pest control
03 Jul 2015
Going organic starts with the right plant in the right place with the right care. But when things go awry, here’s a guide to natural pest control.
By Carol O’Meara
Tea Time
Compost teas are water-based solutions that contain compost microbes, in addition to compost nutrients. Soaking or steeping compost in water makes the tea. Some teas help suppress disease, but it depends on the compost they’re made from; different ingredients can target specific diseases, while others don’t help at all. Compost and its parent ingredients vary widely, and we’re not often told what they are; the compost could be made from yard, brewery or farm waste. For this reason compost teas are best used as nutrient enhancers, rather than for con-trolling diseases.Soaps & Oils


Plant Power
Botanical insecticides are derived from plants. They’re made from flowers, seeds, roots and fruits, and come from a variety of plant families like aster, citrus and peppers. Well-known botanicals include pyrethrins, neem, capsaicin and garlic. These are fast-acting and break down quickly in the environment. Most have low to moderate toxicity to mammals. But some, like nicotine and rotenone, are quite toxic and should be handled carefully. Home-brewed concoctions can be very dangerous, so for safety, purchase these products and carefully follow the label instructions. Timing applications for pest outbreaks is crucial when using botanicals, since they don’t last long in the garden. Neem oil, from neem-tree seeds, controls whiteflies, thrips, caterpillars, aphids, mealybugs, spider mites, scale crawlers and beetles. It’s also effective against powdery mildew. Azadirachtin, also derived from neem, stops insect feeding and acts as a growth regulator that prevents young insects from molting.
Microbial Muscle
Tiny microbes of viruses, bacteria, fungi, protozoa and nematodes pack powerful punches by killing bugs while leaving other creatures alone. Most microbes are host specific, meaning they only target certain bugs. Some, like nematodes, are tricky to use in our dry soils, so talk to your garden center about the ordering and timing for nematodes. They’re usually applied in mid-August to combat Japanese beetles. Bacillus thuringiensis is a popular microbial insecticide derived from a soil bacterium. Known as Bt, it has different strains that work against different groups of insects. Bt must be eaten in order to be effective, but it doesn’t kill immediately. The bug stops feeding, then dies over the next few days. Bacillus thuringiensis var. kurstaki (Btk) acts on the larvae of butterflies and moths. Use it to control leaf-feeding caterpillars like tomato hornworms, cabbage loopers and European corn borers. Bacillus thuringiensis var. tenebrionis (Btt) attacks beetles, including Mexican bean beetle, cucumber beetle and elm leaf beetles. Not all beetles are susceptible, though, so check the label. Bacillus thuringiensis var. israelensis (Bti) kills mosquito and fungus gnat larvae. It’s the active ingredient in mosquito dunks for water features. Spinosad is a fermented by-product of a soil microbe that kills thrips, whiteflies, aphids, leaf miners, scales and spider mites after they eat plants sprayed with it. But be careful: Spinosad is toxic to bees, too, and should never be applied to plants in flower or on windy days.Minerals


Cottontail Controls
Shooing Peter Cottontail and his friends takes more than a scarecrow or a hose disguised as a snake. Rabbits, voles and squirrels quickly figure out these ruses. A short-term solution is spraying with garlic or mint oil to keep creatures out of the garden bed, but those scents are strong to the human nose and must be reapplied after every rain or irrigation. The long-term fix is to remove any cover these animals use for hiding, such as brush or rock piles, low--growing shrubs, and access to areas under decks and sheds. Mow grass low around fruit trees to discourage voles, and install 1-inch mesh fencing around the garden, 3 feet tall and sunk 6 inches into the ground, to exclude rabbits. Just be sure all the rabbits are gone before you install your fencing, so you don’t keep them in instead of out.Beeing Friendly

Carol O’Meara is an entomologist and a local gardening enthusiast. Read her blog at gardening-afterfive.wordpress.com.