Citrus Pest Quick Guide: Ambrosia Beetles1

Lauren M. Diepenbrock and Jamie D. Burrow 2

Ambrosia beetle is the common name for a very large group of small, wood-boring beetles that live in dead or severely stressed trees or cut wood. Ambrosia beetles are attracted to the odor these trees release.

Figure 1. Euplatypus compositus male adult ambrosia beetle.
Figure 1.  Euplatypus compositus male adult ambrosia beetle.
Credit: T. R. Weeks, UF/IFAS CREC

Figure 2. Adult ambrosia beetle left of penny.
Figure 2.  Adult ambrosia beetle left of penny.
Credit: T. R. Weeks, UF/IFAS CREC

Life Cycle

After locating a host tree, ambrosia beetles chew into wood, creating a gallery consisting of tunnels. The beetles carry spores of their associated symbiotic fungus in specialized pouches called "mycangia." After introducing these spores into trees, the beetles "farm" the fungus, which is their sole source of food. Females lay eggs near the fungus, and emerging larvae as well as adult beetles feed on the fungus. Larval development can take weeks to months depending on beetle species, tree host, and weather conditions. After larvae complete development, adults emerge to seek mates and new host trees, repeating this cycle

Damage

Sawdust at the tree base is generally an indicator that ambrosia beetles have bored into the tree trunk. Galleries created by beetles within trees are visible as dark, stained tunnels.

Figure 3. Sawdust at tree base.
Figure 3.  Sawdust at tree base.
Credit: L. M. Diepenbrock, UF/IFAS CREC

Figure 4. Ambrosia beetle galleries inside tree trunk.
Figure 4.  Ambrosia beetle galleries inside tree trunk.
Credit: L. M. Diepenbrock, UF/IFAS CREC

Because ambrosia beetles tend to prefer dead or declining trees, they generally do not affect healthy trees. Only five to ten known species cause damage to important tree species, while the majority are harmless forest dwellers functioning as "nature's recyclers."

Figure 5. Tree trunk cross section with fungus stains and galleries.
Figure 5.  Tree trunk cross section with fungus stains and galleries.
Credit: L. M. Diepenbrock, UF/IFAS CREC

Figure 6. Tree trunk cross section with galleries.
Figure 6.  Tree trunk cross section with galleries.
Credit: L. M. Diepenbrock, UF/IFAS CREC

Footnotes

1. This document is ENY2045, one of a series of the Entomology and Nematology Department, UF/IFAS Extension. Original publication date June 2020. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.
2. Lauren M. Diepenbrock, assistant professor, Entomology and Nematology Department; and Jamie D. Burrow, Extension program manager; UF/IFAS Citrus Research and Education Center, Lake Alfred, FL 33850.