Backyard trees and shrubs are attractive to many different types of beetles. These insect pests are covered by a hard carapace making them especially hard to kill. They bore into the plant, destroying the nutrient transport system and weakening the overall health. If the infestation is serious enough, death may occur. Beetles are very hard to control, but here are some ways to get rid of them.
Choose Trees and Shrubs Wisely and Keep Them Healthy
This may seem obvious, but one of the best practices is prevention. Start by choosing trees and shrubs that are adapted to growing in your area; species that are poorly adapted will struggle and have health issues. Check your USDA growing zone to see if you have the correct climate. Make sure trees and shrubs are planted properly and watered well. This will limit the stress of transplanting. A layer of mulch will help retain moisture but keep the base of the plant free from mulch. A healthy plant has a better chance of withstanding an infestation or avoiding the problem altogether.
Keep the tree or shrub free of cuts and breaks. Avoid pruning when beetles are known to be in the area. Newly cut firewood, dead leaves and other yard refuse are all breeding grounds for beetles.
Different beetles attack different kinds of trees and shrubs, so don't plant the kinds affected if there have been known infestations in your area. You can also try species known to have some resistance.
Hire a Licensed Pesticide Applicator
It is difficult to control beetles using chemicals unless the beetle attacks are detected very early. The pesticides used for large trees and shrubs also very expensive and not usually available to homeowners. However, if you have valuable trees that you would like to try to save, call in a licensed pesticide applicator. They may be able to save trees by spraying the trunks when the adult beetles are flying.
Trees and shrubs that have been attacked in the past but no longer have beetles should not be sprayed. Choose the correct spray for the tree and type of insect you want to eliminate. It is not necessary to spray trees that are not affected. Trees that are highly infested by certain insects cannot be saved by pesticides and should be removed and destroyed.
Anytime chemicals are used in your yard and lawn be sure to ask about any safety precautions. If you are applying pesticides yourself, read the label and application instructions carefully.
Prune Away Affected Branches
If the beetle problem is noticed early enough, you can prune off any infested branches. However, you should be careful when doing this, as new pruning wounds may attract more beetles. Learn the months when the adult beetles are flying and try to avoid pruning during those times.
Cut Down Affected Trees and Shrubs
Cutting down the affected trees or shrubs is the only sure-fire way of controlling beetles in most cases of severe infestations. Usually, by the time the problem is noticed, it is too widespread to be controlled. Pesticides and pruning won't wipe out large beetle populations when the whole plant is affected.
If you have many susceptible trees together, thinning them out can help improve the chances of the remaining trees' survival.
Cut down the affected tree or shrub entirely and destroy the wood. The pieces should be chipped or burned to destroy any beetle larvae. Be sure to move it far away from your remaining trees and shrubs or the beetles may find a new home.
Ambrosia Beetles. University of Maryland Extension
Bark Beetles Management Guidelines. University of California Extension