bluish borer

(Agrilus cyanescens)

Conservation Status
bluish borer
Photo by Babette Kis
  IUCN Red List

not listed


NNR - Unranked


not listed


Bluish borer is an exotic, robust, medium-sized, wood-boring beetle. It is native to Europe and northern Asia. The first sightings in North America occurred in 1920 in Sturgeon Bay, Wisconsin, and in 1921 in Sherborn, Massachusetts. At both sightings they were reported as abundant. The beetle now occurs in the United States from Maine to Virginia, west to Minnesota and Missouri, in western Washington and Oregon, in southern Canada from New Brunswick to Manitoba, and in western British Columbia. It is uncommon in Minnesota, where it reaches the western extent of its range. Larvae hosts include honeysuckle (Lonicera spp.), snowberry (Symphoricarpos spp.), and buckthorn (Rhamnus spp.). The larvae bore under the bark and feed on the sapwood of living branches and twigs, eventually causing these parts to die. However, the beetle does not occur in large enough numbers to be considered a pest of significant concern.

Adults are 316 to 516 (5.2 to 7.8 mm) in length. The body is rigid, bullet-shaped, narrow, and long. The upper side is hairless, metallic, slightly shiny, and uniformly blue, bluish-green, bluish-violet, or rarely bronze.

The head is slightly tucked beneath the first segment of the thorax (prothorax). The antennae are short and have 11 segments. Segments 4 through 11 are sawtoothed. Segments 7 to 11 are as long as wide. The mouthparts are projected downward.

The upper plate covering the prothorax (pronotum) is wider than long, is narrowed in the middle, and has a distinct lateral margin. The lateral margin is rounded. There is no ridge on each side near the rear corners, and there is no longitudinal depression down the middle. The plate between the wing bases (scutellum) is small but visible. It is not crossed with ridges.

The abdomen has five segments. The first two segments are fused together. They are barely visible or not at all visible at the sides. The wing covers (elytra) are slightly narrowed before the middle and tapered beyond the middle toward the tips. They almost cover the entire abdomen. Toward the tip the inner margins are slightly elevated. The tips are separated and rounded. The surface is sculpted like shingles on a roof. The last segment of the abdomen does not have a distinct ridge above.

The last part of the leg (tarsus), corresponding to the foot, has 5 segments. There is a pair of claws at the tip of each tarsus.




Total Length: 3 16 to 5 16 (5.2 to 7.8 mm)


Similar Species

Habitat and Hosts

Honeysuckle (Lonicera spp.), snowberry (Symphoricarpos spp.), and buckthorn (Rhamnus spp.)




May to July




Adults are good fliers.


Life Cycle




Larva Food


Sapwood in the twigs and branches of host species


Adult Food


Leaves of the same plants as the larvae


Distribution Map



24, 29, 30, 82, 83.







Coleoptera (beetles)  


Polyphaga (water, rove, scarab, long-horned, leaf, and snout beetles)  




Buprestoidea (metallic wood boring and false jewel beetles)  


Buprestidae (metallic wood-boring beetles)  




  Subtribe Agrilina  


  Subgenus Agrilus  

Subordinate Taxa


bluish borer (Agrilus cyanescens cyanescens)

bluish borer (Agrilus cyanescens johanidesi)




Agrilus amabilis

Agrilus caeruleus

Agrilus cyaneus

Agrilus fissifrons

Agrilus kyselyi

Agrilus sulcaticeps

Agrilus virens


Common Names


bluish borer












The hardened or leathery forewings of beetles used to protect the fragile hindwings, which are used for flying. Singular: elytron.



The saddle-shaped, exoskeletal plate on the upper side of the first segment of the thorax of an insect.



The first (forward) segment of the thorax on an insect, bearing the first pair of legs but not wings.



The exoskeletal plate covering the rearward (posterior) part of the middle segment of the thorax in some insects. In Coleoptera, Hemiptera, and Homoptera, the dorsal, often triangular plate behind the pronotum and between the bases of the front wings. In Diptera, the exoskeletal plate between the abdomen and the thorax.





Visitor Photos

Share your photo of this insect.

  This button not working for you?
Simply email us at
Attach one or more photos and, if you like, a caption.

Babette Kis


Agrilus cyanescens bluish wood boring beetle

Agrilus cyanescens, bluish borer, at the hedgerow at Barnes Prairie, Racine Co., WI. Photo taken May 31, 2021.

  bluish borer  

Alfredo Colon

    bluish borer   bluish borer  
    bluish borer      








Visitor Videos

Share your video of this insect.

  This button not working for you?
Simply email us at
Attach a video, a YouTube link, or a cloud storage link.


Other Videos
  Metallic Wood-boring Beetle (Buprestidae: Agrilus cyanescens)
Carl Barrentine

Jun 12, 2011

Photographed at the Turtle River State Park, North Dakota (08 June 2011). Thank you to 'v belov' and T.C. MacRae ( for confirming the identity of this specimen!




Visitor Sightings

Report a sighting of this insect.

  This button not working for you?
Simply email us at
Be sure to include a location.
  Alfredo Colon

Location: Woodbury, MN

bluish borer  
  Alfredo Colon

Location: Woodbury, MN

bluish borer  
  Babette Kis

Location: Barnes Prairie, Racine Co., WI

bluish borer  






Created: 11/21/2022

Last Updated:

About Us | Privacy Policy | Contact Us | © All rights reserved.