As we get closer to spring, it’s time to start thinking about protecting our trees and shrubs from emerging pests. When temperatures begin to rise, many different insects will re-emerge from their overwintering spots or hatch from eggs deposited on your trees the previous season. Of all the pests that can harm your trees and shrubs, there is one group of insects that usually gets overlooked. Scales or tree scales are tiny insects that feed on the sap of trees and plants. Depending on the species, scales can cause a lot of damage to trees and fruit trees.
When these insects feed, their piercing mouthparts inject a toxin into the plant as it feeds, causing yellowing of tissue, reduced growth, and branch dieback. Soft scale insects secrete a waste called honeydew, which can attract bees, wasps, ants, and flies. Honeydew can also be the host of a fungus called black sooty mold, which can make your trees look unattractive. Although sooty mold is harmless, if there is enough present, it could shade out sunlight and stunt the tree’s growth.
There are two types of scale insects: armored scales and soft scales.
Soft Scale Insects
Armored Scale Insects
The most common species of scale in Mississippi and Louisiana are magnolia scales, which can be a serious pest of magnolias such as Japanese or Star Magnolia. Magnolia scale sometimes occurs on evergreen magnolias such as the Southern Magnolia or Little Gem. Oak lecanium scale, which appears on many oaks and is especially common on willow oaks in urban areas.
Infestations can weaken host trees or even kill the tree if it is bad enough. Damage to an infected tree can include:
Scales have a unique life cycle that makes them rather hard to control. When temperatures warm up in the spring, overwintering scales emerge from a protective wax covering and mate. Unlike other insects, female scales give birth to live young instead of laying eggs. She can give birth to 150-500 crawlers during the season. Crawlers are so named because they are born with six legs and spend their time crawling around the tree and feeding on the sap. After three weeks, the crawlers molt and lose their legs and antennas to become armored adults.
Management of tree scale in Mississippi and Louisiana is tricky and varies from species to species. As we mentioned above, these insects have either a protective wax coating or a hard shell, making controlling these insects difficult. Dormant oils are moderately effective on overwintering soft scale species but need to be applied in early spring before trees come out of dormancy. They are even less effective on armored scale species. Natural enemies, such as birds, wasps, flies, and beetles, feed on adults, as well as crawlers.
The trick to controlling tree scale is to know when they are at their most vulnerable, which is the crawler stage. Properly timed insecticide sprays can help manage tree scale by killing the young crawlers. Unfortunately, adults are well protected against chemical attacks.
Remove the Tree
When trees die, it is usually from diseases or infestations. Keeping your trees and shrubs protected from tree scales can keep them strong and healthy, but sometimes infestations are just too much for the tree. In these instances, the most responsible thing to do is to remove the tree to prevent it from spreading to others.
Even though it’s January, it’s not too late to sign up for tree and shrub care. At TruGreen, it is our job to protect your trees and ornamentals. Our 7-step tree and shrub care program is designed to keep your trees strong and healthy all season long.
Call us at 225-465-0665 if you are a Louisiana client, but if you’re from Mississippi, call us at 662-330-1330. Or get a free and easy quote here. Get access to all our tips on pest control, lawn care, tree care, and more by following our monthly blog.