Skip to Content

by High Country Gardens

Insect & Flower - Jobob ArikanSummer is the time to focus on protecting your garden from insects.

Eco-friendly & Organic Ways to Deal with Garden Pests

By now most of you have your trees, shrubs, perennials and annuals planted. So at this point you have the time to focus on other aspects of your gardens. Just as we enjoy the warmer days of summer, so do all the bugs and grubs and other pests.

Unfortunately, there is no one product that will solve all your problems and be organic, non-toxic, environmentally safe, yet lethal to insects. However, remedies do exist for specific pests, and we'll review some of them here. Remember that you are trying to reduce rather than eradicate the insect population.

Organic Insect Control for Aphids

These can be a major problem for roses as well as the broccoli and cabbage family. These can be controlled with Safer Insecticidal Soap, which will kill them on contact. It is important to repeat the application every 48 hours, three times, to be sure to kill the eggs as they hatch. Aphid eggs are air-born and can be a problem throughout the summer so make sure to keep an eye out for more and spray again. To control Aphids around your broccoli, spread aluminum foil on the ground. For some mysterious reason aphids don't like the foil and stay away. Ladybugs and praying mantises can also reduce the aphid population.

Organic Insect Control for Grasshoppers

The least toxic way to deal with grasshoppers is to use Nolo Bait. This bait contains "Nosema locustae", a spore that infects the digestive tract of grasshoppers but is harmless to birds or other animals that might eat the infected grasshoppers. As a grasshopper ingests one flake of the bran it becomes infected and begins to eat less and less. After 3 to 4 weeks about 50% of the population will be dead. Then, as uninfected grasshoppers eat their fallen comrades, they too become infected. Infected females pass the disease through the egg-laying process. Nolo Bait is most effective when applied during the early morning hours when grasshoppers are actively feeding.

Remember that you are trying to reduce rather than eradicate the insect population.

Organic Insect Control for Leaf-Feeding Caterpillars and Worms
Green Leaf-Feeding Caterpillars - Organic Insect Control
Bacillus thuringiensis works well for leaf-feeding caterpillars and worms, such as this tomato hornworm, and it is considered nontoxic up to the time of harvest.

For leaf-feeding caterpillars, tomato hornworms, and cabbage worms, fortunately bacillus thuringiensis works well for these pests, and it is considered nontoxic up to the time of harvest. Two forms work well for this, Thuricide, which is a liquid form, and Dipel, which is a powder form.

Organic Insect Control for Pear, Cherry, and Plum Slugs

These little (1/4" long) slugs feed on the leaves of these trees and by the end of the season the leaves have a skeletonized look. You can use wood ashes on these slugs—the ash will stick to their bodies. You can also use a Pyrethrin Insecticidal Soap, which will kill them on contact.

Organic Insect Control for Cutworms

Young transplants are particularly vulnerable to cutworm damage. You can keep cutworms away by creating barriers made from milk jugs or paper cups around the plants. Sprinkling cornmeal around plants also helps because the cutworms can not digest it, however, repeated applications may be necessary. Baits such as DeBug or Diazinon Granules are effective. The best time to use a bait is in July and August when cutworms are actively feeding.

Organic Insect Control for Codling Moths

These are the most common nemesis of apples—the proverbial worm in the apple. The moths lay eggs on the leaves, and then the hatching eggs migrate to the fruit. They tunnel through the fruit feeding primarily on the developing seed. After three to four weeks they leave the fruit and crawl or drop down the tree to spin a cocoon, which produces a second generation in about two weeks. Bacillus thuringiensis or other insecticides will work well on these if you apply them during the peak periods when the moths are laying eggs.

These are the most common nemesis of apples—the proverbial worm in the apple.

Generally there are two generations per season (late spring after petal fall and mid-summer). Feeding by the second generation of moths causes most fruit damage. Pheromone traps, which contain sex attractants of the female moth, can improve treatment timing. Insecticides are most effective 10 to 14 days after peak flights are detected in pheromone traps. The traps may also confuse the male moths so that there is less mating. Another method used is to have a gallon jug baited with a pool of fermenting molasses and water (1:10 to 1:15 dilution is suggested). This attracts both male and female moths.

As you can see, there is no simple solution for pest control. There are a number of books available on the subject. One that is especially informative is Pests of the West by Whitney Cranshaw.

© All articles are copyrighted by High Country Gardens. Republishing an entire High Country Gardens blog post or article is prohibited without permission. Please feel free to share a short excerpt with a link back to the article on social media websites, such as Facebook and Pinterest.