It can be extremely unsettling to see your healthy live oak trees suddenly stripped of all their leaves. When this happens, the culprit is often the California oakworm. Because the oakworm is a generally beneficial native species, it can be hard to tell when you need to treat for it and when it is best to leave them alone. Learning the difference between a normal year and a dangerous infestation can help.

What is the California oakworm?

The California oakworm is the larva of a native moth. As a caterpillar, it grows to about three centimeters in length. It has a head that ranges from red to dark brown and a pair of yellow stripes along its back. The adult moths, known as oak moths, can often be seen at dusk and are brown or gray in color. They have a body length of 1.25 centimeters.

Oakworm eggs are laid on the underside of oak leaves. They are small, round white eggs that take on a pink or brown hue before they hatch. The young caterpillars eat tissue from the bottoms of the leaves when young, but will skeletonize leaves as they grow large enough to digest the heavier material.

The oakworm is considered a valuable part of both wild and urban landscapes in northern California. It provides food for a wide array of birds and insects. Due to this, it is important to address the best way to protect your trees while also protecting the surrounding environment.

Outbreaks of oakworm can be unpredictable. In some areas, you will find a number of the worms reliably each year. In others, you may have a heavy outbreak one year, but then not see any at all for several years.

Do you need pest control for California oakworm?

Seeing all of the leaves stripped from your tree can make you feel that the tree is in trouble. However, that is not always the case. A healthy live oak tree can typically survive defoliation. However, a tree that is not healthy may suffer additional damage due to the stress of a caterpillar attack. This can result in lost limbs or increased susceptibility to disease.

It is also necessary to get a proper diagnosis. Other tree issues, such as root rot, can lead to defoliation that resembles that caused by oakworms.

In many cases, it is fine to allow caterpillars to continue to feed without intervention. However, the caterpillars can become troublesome when they congregate in large numbers on outdoor furniture. Sometimes people will have trees treated for aesthetic reasons, as well. Pest control efforts can also be applied to specific trees. Systemic injection, for instance, can protect an individual tree from caterpillars for an entire year without a need for retreatment. This way, you can treat important trees that provide shade in your favorite outdoor areas while leaving those further from your home alone.

Are California oakworms defoliating your trees? We can help you determine the best way to keep this pest in check. Call American Rat Control today for a consultation.