Charles H. Bronson, Commissioner    -    James R. Karels, Director
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Insects of CONIFER AND HARDWOOD BRANCH AND STEM
Ambrosia Beetles
Drywood Termites
Galls
Flatheaded Borers
Carpenter Ants
Roundheaded Borers
Twig Beetles


 

Forest Health > Insects and Diseases publication

INSECTS of... Conifer/Hardwood Branch and Stem

Common Name:

AMBROSIA BEETLES

ambrosia sawdust pile.

Sawdust pile indicative of a AMBROSIA BEETLE infestation.

Other:

 Pinhole borers
Shothole borers
Species Gnathrotrichus sp.
Platypus spp.
Xyleborus spp.
Xylosandrus spp.
Common Hosts:

Hardwoods
Softwoods

Description
 Adult -- Gnathrotrichus, Xyleborus, and Xylosandrus approximately 1.5-3.3 mm long; head and body reddish-brown to black; stout robust shape; Platypus approximately 5.0 mm long; head and body light to dark brown; elongate cylindrical body.
Pupa -- similar to adult; creamy white.
Larva -- size variable, approximately 2-6 mm long when mature; head light brown to amber orange; body creamy white; legless.
Importance
 Ambrosia beetles generally utilize dead, dying, or severely stressed or weakened trees as well as seasoning logs or lumber. Timber values decrease not only because of the pinholes made by beetles but also the staining by ambrosia fungi brought into the galleries by the beetles.

Biology and Habits

 Adult beetles emerge from infested material year-round, mate, and females deposit eggs in galleries constructed in sapwood and heartwood. The larvae feed on the special fungi - the ambrosia - first brought in by the parent adult beetles. The fungi actually feed on wood fiber, not the ambrosia beetles. Pupation occurs in the galleries. Mating occurs in galleries and only females fly to new hosts, or both sexes fly to a new host and then they mate.
Number of Generations
 Several generations per year.
Signs of Infestation
 One or more piles of white fluffy boring dust at base of an infested tree. Small holes (0.5-3 mm wide) through the bark and into sapwood and heartwood, referred to as pinholes or shotholes. Split wood with small diameter galleries running with and against the wood grain. Galleries free of frass or sawdust. Staining of wood in association with galleries, referred to as pinholes, shotholes, or grease spots.
Control
 Prompt removal and disposal of infested material. A severe stem infestation is usually indicative of a dying tree; salvage cut as soon as possible. Use an approved insecticide for infested and nearby susceptible trees. Promote tree vigor and health to minimize possibility of ambrosia beetle infestation.



Bulletin No. 196-A | Printed October, 1983 | Contact the Forest Health Section
Division of Forestry Shield


Florida Department of Agriculture and Consumer Services