Due to our mild winter and drought, conditions are perfect for pests. Many of us northern Nevada gardeners are struggling with one pest in particular right now—aphids. Aphids are small, soft-bodied insects. They are about one tenth of an inch long, and they are teardrop shaped. Aphids have long, slender mouth parts to pierce plant tissues and suck plant sap. These pest insects may or may not have wings, and they come in many colors. Aphids can be pink, yellow, green, gray, deep blue or black.
Many aphids found in Nevada overwinter as eggs, hatching with warming temperatures in early spring. The newly-hatched aphids begin to feed and complete their development in one to two weeks. Then, they give birth to live young, without mating, at the rate of one to twenty per day!
Also known as plant lice, aphids are found on nearly every species of wild and cultivated plant. When aphids are present in our gardens and landscapes, they tend to congregate on leaves and shoots, especially at the tips of new shoots. They prefer the undersides of leaves and fresh, new growth for feeding and for protection from Nevada’s sun and drying conditions. Young leaf and flower buds are favorite targets. Aphids also feed on flowers, foliage, twigs, branches, trunks or roots of herbaceous and woody plants. They may live entirely on one type of plant, or they may spend part of their development on one and then move to another.
If we do not notice aphids in the landscape early on, their damage can tip us off to their presence. Small seedlings may be severely damaged or killed by aphids. When abundant, aphids can even cause serious damage to larger plants. Some species of aphids have saliva that, when injected into plant cells during feeding, causes abnormal– often twisted– plant growth. Sometimes, this is the first obvious sign of a heavy infestation.
Another tip-off is aphid excrement, a sweet substance called honeydew. It can fall onto leaves, patios, vehicles, walkways, etc., causing a sticky nuisance. Some wasps and ants are attracted to and harvest the honeydew for food. They will also protect the aphids from natural predators to safeguard their food source.
Gardeners can use integrated pest management (IPM) to reduce the impact of aphids in the home landscape. IPM has a long name, but the concept is simple. Start with the least toxic control methods first. Using IPM techniques saves money and protects the environment. For information about IPM, visit www.manageNVpests.info. A few IPM steps to take when managing aphids include:
- Select plants that are unattractive to aphids.
- Grow plants that attract and provide habitat for aphid predators.
- Release aphid predators like ladybeetles or praying mantis.
- Control the ants that protect the aphids.
- Prune and destroy heavily-infested parts of plants. Clean and sanitize pruners after each cut.
- Knock aphids off affected plants with a strong stream of water. Aphids will fall to the ground, and exposure to the sun will most likely be their demise.
- Lastly, apply pesticides, like an insecticidal soap, for aphid control.
Under most conditions, it is not necessary to use pesticides for pest control. Beneficial insects, the natural enemies of pest insects, will do a good job of keeping pest populations at bay. When choosing a pesticide, keep in mind that most kill beneficial insects as well. This may disrupt the balance between beneficial and pest insects in your garden and exacerbate your pest problem. Select the least toxic chemical available to beneficial insects, and spray only the plant or portion of the plant that is infested. Always follow the label instructions on all pesticides before application.
Liz Morrow is a Certified Master Gardener Volunteer with University of Nevada Cooperative Extension. Have questions about your plants? Contact a master gardener at 775-336-0265 or firstname.lastname@example.org, or visit www.growyourownnevada.com. For information on drought, visit www.livingwithdrought.com.
Warriors in the Garden
Sidebar by Wendy Hanson Mazet
Insects of every shape and size prey on our gardens and landscapes. It is easy to see a bug and take drastic action. But, before taking action, it is important to identify creatures to make sure they really are pests and not actually warriors fighting to help. Many people chemically treat problem areas, never realizing that doing so kills beneficial insects we want and need in our yards.
The warriors of the garden are commonly called predator or beneficial insects, and they feed on pest insects that harm our plants and destroy our harvests.
Lady Beetles, frequently called ladybugs, are a favorite garden warrior. Most people recognize the adult ladybug, but ladybug larvae eat more aphids, thrips, spider mites and leafhoppers. The immature Lady Beetles are dark colored and are elongated like an alligator. They have orange or yellow spots. When it is time for the larvae to go through metamorphosis and change into the beetle we all know, they attach themselves to a plant and form an orange pupa with black dots. Within a week, a ladybug will emerge.
Green Lacewings are another favorite of gardeners. They also go through a metamorphosis to change from egg, to larvae/nymph, then to chrysalis and then to the beautiful Green Lacewing adult. The larva, commonly called nymphs, of Lacewings look like a miniaturized cream-colored alligator with brown markings and large pinchers. They use these pinchers to capture and eat other soft bodied insects like aphid.
While many people may not like spiders, what they may not realize is that many spiders do not create webs and instead are hunters. These hunters seek out and kill pests like beetles, caterpillars, leafhoppers and aphids. A few common ones in our area are wolf spiders (commonly found in sheds, homes and gardens) as well as crab and jumping spiders (they prefer gardens and landscapes).
There are many more beneficial insects, spiders, mites, flies and wasps in northern Nevada gardens and landscapes. The next time you find a critter you don’t recognize, let us identify it for you. It may just be a garden warrior. We will also give you information and options on how to handle your pest problems. You can also visit www.manageNVpests.info for information on both beneficial and pest insects.
Wendy Hanson Mazet is a certified arborist and horticulturist with University of Nevada Cooperative Extension in Washoe County. Have questions about your plants? Contact a master gardener at 775-336-0265 or email@example.com, or visit www.growyourownnevada.com. For information on drought, visit www.livingwithdrought.com.