Garden pests like squirrels, deer, and rabbits damage plants. Other animals like chipmunks, skunks, and raccoons dig in gardens. Prevention is the best approach. Choose healthy plants for your yard or garden and plant a mix of flowers to attract beneficial insects like ladybugs, lacewings, and praying mantis.
Several natural methods for managing pests include diatomaceous earth, pheromone traps, and nematodes that control root weevils. Organic pyrethrin sprays and neem or horticultural oil also kill many common harmful bugs. Learn how to get your garden healthier by talking with Killian Pest Control experts.
Cutworms
Cutworms are the larval form of certain moths that damage vegetables, flowers, and fruit crops by slicing through stems at or near ground level. They are most damaging when their numbers are high, but even a small infestation can destroy seedlings and young plants. They can also chew leaves and wilt blossoms. Many species of this night-flying family (Noctuidae) overwinter in the soil as pupae, but most are active in early spring and can be found at the base of plants, where they feed.
Scout your garden frequently to check for these pests. When scouting, note the stage of larval development as this will help determine whether chemical intervention is warranted. Small larvae (12 to 18 mm or 0.5 to 0.7 of an inch) are most susceptible to damage, but when they reach 30 to 35 mm (1.2 to 1.4 inches) the danger is past and a control measure may not be needed.
Prevention is the best approach to controlling cutworms. Delay planting to early spring, as these pests are most active at this time. Remove weeds and mow lawns closely to limit places for them to hide and lay eggs. Till the soil in fall and spring to expose overwintering larvae and moths and kill them.
Spread a layer of diatomaceous earth on soil surfaces where cutworms are known to occur. This powder, made from the fossilized abrasive remains of prehistoric marine life, isn’t harmful to humans or animals but scratches and dehydrates insects that crawl over it. It can be purchased in a form suitable for use in organic gardens and is available from most garden centers.
Spider Mites
Spider mites are small, wingless insects that are a common problem in the greenhouse and many houseplants. They are a major pest of typical greenhouse crops such as tomatoes, cucumbers, and peppers, but they also target many fruit trees, ornamentals, and garden plants. They tend to be most active in hot weather and are blown to new areas by wind. They can also hitch a ride indoors on new houseplants or even in the soil of potted plants brought inside for the winter.
The best preventative measure is to keep a close eye on your garden and houseplants, particularly the undersides of leaves. When you spot webbing, stippling, or other signs of an infestation, prune out affected leaves and stems and discard them in the trash (not the compost pile!). Regularly pruning and weeding around plants will help to remove hiding places. Plants that are stressed by heat, drought, or other factors are more prone to spider mite attack. Be sure to water them as needed to prevent overwatering and keep them hydrated with plenty of light and air circulation.
Chemical control is usually unnecessary, but horticultural oil and insecticidal soaps can be used as spot treatments on heavily-infested plants to kill them. For long-term eradication, try introducing predators that prey on spider mites. Commercially available predatory mites such as ladybugs and lacewings are ideal, but there are also specific predatory mites that work better against some species of mites than others.
Another option is to use predatory mites that are specifically designed for two-spotted spider mites (Phytoseiulus persimilis). These are harder to find but will provide a natural method of controlling them. They can be released indoors or outdoors at a rate of one predator per 10 spider mites, and they are especially effective on perennial plants such as tomato, pepper, and eggplant.
Hover-Flies
Hoverflies (also called syrphid flies) are an important group of pollinators, and their larvae eat garden pests. They are also efficient nutrient recyclers, contributing to the natural balance of a garden.
Adult hoverflies feed on nectar and pollen, helping to ensure a good harvest of flowers and other plants. The larvae, on the other hand, are a valuable pest control for gardens as they voraciously consume soft-bodied insects such as aphids.
As a result, they are an important part of integrated pest management (IPM) programs for many crops. They help to keep aphid populations under control and can help reduce aphid outbreaks even if the aphid population is high in other areas of the field.
The hoverfly larvae are saprophagous (“feeding on decaying plant matter”), but they will also target herbivorous insect pests such as aphids, thrips, and caterpillars. They have hooks for jaws that enable them to grasp and hold the insects, which they then devour with ruthless efficiency.
Hoverfly larvae are also efficient nutrient recyclers, which means they break down the waste of other organisms to convert it back into usable energy. As a result, they are nature’s cleanup crew.
Grow plenty of flowers with small florets in spring and summer to support a healthy population of these beneficial insects. In particular, consider growing sweet alyssum, coreopsis, dandelions, and members of the carrot family. In addition, reduce mowing during peak pollinator activity and leave a patch of wildflowers to provide a habitat for these insects.
The adult syrphid flies take a generalist approach to foraging, visiting a wide range of flowering species. However, some species are highly selective, such as the marmalade hoverfly (Episyrhus balteatus), which only visits Ranunculus repens.
Praying Mantis
Praying mantis has been heralded as the ideal natural replacement for chemical pesticides in the garden. They prey on a wide variety of pests, including aphids, flies, mosquitoes, caterpillars, leaf-chewing beetles, and more. They are also effective predators of hornets, wasps, ants, bees, and crickets.
The presence of praying mantises in the garden is often a sign of a healthy, biodiverse environment because these carnivorous insects thrive in areas that are teeming with other insect life, their primary food source. Because of this, they are excellent natural pest control in gardens and farm fields where there is a lot of other insect activity.
You can encourage praying mantis to inhabit your garden by providing places for them to hide and rest. Planting tall grasses and shrubbery that provide shelter and security will be helpful. Also, make sure to provide a shallow dish of water so they can sip their thirst during the hot summer months.
When you’re ready to introduce praying mantises into the garden, you can purchase dormant egg cases (known as ootheca) from many online and local garden supply stores. They are easy to place around the garden where you want them to hang out, and they will become active as soon as they receive the food they need.
Keep in mind, though, that purchasing mantis and releasing them in the garden is no guarantee of success. Like any other insect, they are subject to predators, and if they don’t find enough food in one garden, they will move on to another. In addition, mantises are generalist predators and will eat both good and bad insects, so they aren’t a magic bullet for controlling garden pests.
Nematodes
Nematodes (phylum Nematoda) are microscopic, free-living worms that are important components of most soil and marine ecosystems. Although most nematodes are not harmful to plants, a few species such as potato cyst nematodes (Globodera) root-knot nematodes (Steinernema feltiae and Steinernema carpocapsae), leaf and bulb nematodes (Ditylenchus species) and stem and wireworm nematodes (Heterorhabditis bacteriophora) do cause plant damage.
Symptoms of nematode damage are often seen on the surface of the plant such as stunted growth and discolored or dead parts. Symptoms below ground are more subtle; a nematode-infested plant may have a shallow, narrow root system with swollen areas where roots meet the soil. Nematodes also can interfere with nutrient uptake causing nutrient deficiencies in affected plants.
Several methods can be used to control nematode problems. Crop rotation, in which susceptible crops are not grown in the same garden area for more than one year, is a simple but effective way to avoid nematode damage to most vegetables and herbs. The use of nonsusceptible plants, such as grass, in the same garden site for three years can reduce nematode numbers in that area as well.
Soil amendments, such as compost or aged pine bark, that improve soil structure and encourage a deep root system can help minimize damage from nematodes. Incorporating these amendments into the soil before planting is best.
Biological controls for several species of nematodes are available from most garden centers. These are living organisms and are supplied in small quantities in spray or soil drenches for use at specific times of the year when the conditions needed for their survival are met. Usually, they are labeled for the particular pests that they are intended to control; for example, nematodes for ant control are labeled as Heterorhabditis bacteriophora while nematodes for chafer grubs and leatherjackets are labeled as Steinernema hexaflumcens.