Pest Alert – Ambrosia Beetles

Skip to main content N.C. Cooperative Extension Homepage County Centers Topics Contact Us Become a Student Give Now Henderson County Center place100 Jackson Park Rd, Hendersonville, NC28792 (828) 697-4891 Closed Today Events Meet Our Staff Hurricane Helene Soil Testing 2025 Pesticide Classes & Schools Henderson County Farmers Markets Newsletters Prior Year’s Newsletters Henderson County 4-H 4-H News and Updates 4-H Clubs – Henderson County 4-H Online Enrollment 4-H Project Records 4-H Presentations 4-H Overnight Camp(s)! 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Also, as more people move to the area and plant susceptible plants, we have been seeing more trees being attacked over the past years. Crape myrtles, Japanese Maples, redbud, and many other trees are susceptible. We even see the pesky insects in fruit orchards and vineyards where they kill weak plants. Ambrosia killed maple spring 2025 Ambrosia killed maple (on left) spring 2025. This could be related to damage caused by Hurricane Helene. Photo courtesy of Steven Carrol Schneider Shrub and Tree. This group of wood boring beetles is made up of many different species. Ambrosia beetles drill holes into trees Ambrosia beetles drill holes into trees Some ambrosia beetles are native, performing a very important ecological role as decomposers by breaking down dying trees. Other ambrosia beetles are non-native having been introduced from Asia and Europe in untreated packaging materials such as pallets. Species vary in size from 1/10 – 1/4 of an inch, most considerably smaller than a grain of rice. Ambrosia beetles drill into wood creating holes smaller than the diameter of a pencil lead. They do not eat the wood; they gnaw it and push it out behind them as they construct their tunnels. Sometimes a toothpick-like protrusion of sawdust will form at the hole. Ambrosia beetles drill into plants pushing out sawdust Ambrosia beetles drill into plants pushing out sawdust The beetles do not eat the wood. Rather, their larvae which they deposit in their tunnels, eat a fungus. They carry the fungus on their bodies and as they drill into the tree, the wood is infected. The drilling of most ambrosia beetles is harmless while the fungus actually kills the plant by clogging the stem so no water can move up from the roots. Adult beetles emerge from infested trees and seek out sick trees in February when we get a few days of warm weather. The beetles actually smell chemicals released by sick trees. Often, they will reenter the same tree where they were born. There will be two or three generations of the beetle per year. Ambrosia beetle larvae feed on ambrosia fungus Ambrosia beetle larvae feed on ambrosia fungus The best control of the ambrosia beetle is to keep your trees as healthy as possible. Plant them correctly and avoid over-watering. Do not damage trees and do not use too much mulch over the root system. If you have a particularly important plant that you do not want to lose or if you have had trouble with ambrosia beetles before, a spray of bifenthrin insecticide applied to the bark of the trunk of the tree in Mid-February, mid-March, and mid-April can offer protection. ambrosia beetle maple Ambrosia beetles attack stressed trees. The insect smells stressed trees. This maple has not grown quickly enough to shed its bark. Lichens are a sign that a plant is not growing. Written By Steve Pettis, N.C. Cooperative Extension Steve Pettis, Jr. Extension Agent, Agriculture - Consumer and Commercial Horticulture N.C. Cooperative Extension, Henderson County Center Updated on Mar 31, 2025 Was the information on this page helpful? Yescheck Noclose Excellent! We're glad you liked it. What made it so helpful? (Optional) Send Explanation Share this Article Post Facebook LinkedIn emailEmail Article's Short URL: go.ncsu.edu/readext?580867 More on: Agriculture & Food Commercial Horticulture, Nursery & Turf Entomology Ipm Pesticides Insects Hurricane Helene Ipm Lawn & Garden Pest Management Join our mailing list! Enter your email address to receive updates. Email* Enter Your Email Address First Name Optional Last Name Optional What topics are you interested in? 4-H Newsletter List Beekeepers Community Health and Nutrition (FCS) General Interest Please keep this box b•l•a•n•k Subscribechevron_right We also have a few other email lists you can subscribe to. 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I used this article to learn about the ambrosia beetle for my article on red bays, which I published in the 7/1/2025 SPVCA newsletter and Paperless Ponte Vedra.