Watch for These Spring Tree Pests
April 22, 2021
A new season brings new insects to the landscape – some are good, while others are not. Here’s a few you should watch out for this spring season.
Aphids are one of the most commonly found insect pests. They multiply very quickly, especially in warm & humid weather. They are most often found on crape myrtles, post oaks, bur oaks, American elms, and many landscape shrubs, perennials, and annuals.
Aphids are tiny, rounded insects usually green in color, but certain species are orange, yellow or black. They coat stems and leaves & are traditionally found near new growth, where they feed by sucking & piercing mouthparts, causing distortion of new growth. Additionally, as these insects suck moisture from tissue, they leave behind a sticky excrement (called honeydew) that can attract other pests. You’ll often see ants need lots of aphids.
An outbreak of aphids can cause heavy damage on already stressed trees. So, the best defense is a healthy, properly watered & pruned tree.
Keep your ladybugs populations healthy. Ladybug larvae can consume up to 250 aphids each day! Or 5000 in its full lifetime!
If you have tent caterpillars, you'll probably know it! These voracious eaters can defoliate a tree if they are present in large numbers. Defoliation can stunt future growth and vigor of your trees, especially if the tree is already stressed. You often see tent caterpillars in oak or sycamore trees.
Tent caterpillars feed & live in large groups. They build a web on branches on tree trunks where they cluster together – leaving the web to feed. Sometimes these webs are high up in the tree canopy and you may not notice them until the caterpillars have done damage.
If a population of tent caterpillars can be identified early, we can use a non-toxic, organic biological control called BT to treat. Bacillus thuringiensis is a bacterium that is deadly to the insect, but safe for the environment.
Emerald Ash Borer
One of the most significant insects in regards to its impact, is Emerald Ash Borer (EAB). EAB is a beetle, native to Asia, which slipped into the US in the early 2000’s. The ½” long metallic green beetle does its damage in the larval stage. The larvae burrow into the trunk of Ash trees and feed under the bark, leaving ‘galleries’ which disrupt the transportation of water and nutrients throughout a tree – killing the tree within 2-3 years.
The adult emerges in the spring, so it’s important to keep your eyes open for the insect & report it to extension immediately. Since EAB attacks both healthy & stressed trees, it is a pest that causes great damage everywhere it is found. Although we do not have large populations of ash trees in North Texas, tracking the spread & staying ahead of EAB is very important for forests across the US.
Signs and symptoms of the EAB being present include:
· thinning or dying of tree crowns
· suckers at the base of the tree
· D-shaped exit holes (where the adult beetles emerge)
· splitting trunks
· heavy woodpecker activity
Learn more about EAB here
Spider mites begin to pop up in the spring & really take hold once hot weather hits. The miniscule insects live on the undersides of leaves, and therefore, aren’t the easiest to spot. A telltale sign they are present is the distinct, thin webbing they produce. They also produce a pattern called ‘stippling’ as they feed, which is tiny speckling on leaves where they pierce the tissues.
Severe infestations can cause leaves to curl & drop from the plant. Drought & heat speed up the life cycle, and exacerbate the overall issue. If you notice a small population of spider mites on your ornamental plants, spray them with a strong stream of water to knock the populations down (and repeat over the course of the next few days). A diluted solution of liquid seaweed or soap or horticultural oils also help to reduce populations.
As with others, spider mites attack plants in distress first. Keeping plants well-watered will help to keep spider mites at bay.
If you notice any insect issues in your trees or landscape, or notice a general lack of vigor, give us a call to schedule an evaluation.
Posted: April 22, 2021