The ABCs of Tree Health – Part 2: Insects

Certified Arborists Serving Ventura & Los Angeles Counties

News And Advice From The Leading Thousand Oaks Tree Trimming Company

Are you happy with the look of the trees in your yard? Are they lush and green — or plagued with brown leaves and damaged bark or somewhere in between? If yours fall into the not-so-hot category, it’s good to brush up on some basics to help you diagnose the problem.

Trees can be affected by both disease and insects. Last month we took a look at problems caused by disease. This month we’ll cover problems caused by insects. In either case, if you notice a problem with your trees, it’s best to start examining them and taking notes. That’s the first step in selecting an appropriate treatment.

Step One: Correctly Identify The Problem

Simple as it sounds, you need to know what kind of tree you have to correctly identify the problem. This is because many insects only attack certain types of trees. Make sure you know what kind of tree you have and you’ll immediately limit the your list of suspects.

Some insects can cause injury and damage to trees and shrubs. In many cases, however, the insect problem is secondary to problems brought on by a stress disorder or pathogen. So review the basics about identifying stress problems here.

If you’re pretty sure it’s not a disease, then you can start considering the possibility of an insect problem. First, remember that most insects help trees rather than hurt them. They assist in pollination, and they can act as predators of more harmful species. So resist the temptation to simply get an insecticide and start killing all insects with­out regard to their kind and function. You may end up doing more harm than good. You can divide insects into three categories according to their method of feeding: chewing, sucking and boring. The good news is that each manner of feeding leaves its own distinctive pattern of damage and that can help with diagnosis.

Chewing Insects

Look for damage from chewing insects that includes uneven or broken margins on the leaves, leaves that look like they have left only skeletons and leaf mining. You’ll see this damage on plant tissue such as leaves, flowers, buds, roots and twigs.

What kind of insect does this damage? They include adult beetles or beetle larvae, moth larvae (caterpillars) and many other groups of insects.

Sucking Insects

Sucking insects insert their beak into the tissues of leaves, twigs, branches, flowers or fruit. That is the way they feed on the plant’s juices. Sucking insects include ones that you’ve probably heard of — aphids, mealy bugs and leafhoppers. Look for damage from these pests in the form of dis­coloration, drooping, wilting, leaf spots or general lack of vitality in the affected plant.

Boring Insects

The damage from a boring insect can be severe because the damage begins underneath the tree’s bark. Boring insects start out as larvae beneath the bark and spend time there, boring into the stem. They then subsequently develop into adults. Other borers, bark beetles for example, mate at or near the bark surface and lay eggs in tunnels beneath the bark. If you’re having trouble identifying any of these issues, give us a call – we’d love to help you out!