white-spotted sawyer

(Monochamus scutellatus scutellatus)

Conservation Status
white-spotted sawyer
 
  IUCN Red List

not listed

 
  NatureServe

NNR - Unranked

 
  Minnesota

not listed

 
           
           
           
           
           
           
           
 
Description
 
 

White-spotted sawyer is a moderate-sized, shiny black, wood-boring, long-horned beetle.

The adult female body is robust, broad-shouldered, ¾ to 11 16 long, and 3 16 to ¼ wide. There is a large, blunt projection on each side of the hardened covering of the thorax (pronotum). The hardened forewings (elytra) are shiny black, have a metallic appearance, and have small patches of white hairs. The small triangular plate between the bases of the elytra (scutellum) is covered with white hairs.

The face is nearly flat. The antennae are black, are longer than the body, and project from a notch in the eyes. When they are held back along the body the last two or three segments extend beyond the elytra. Two segmented feeler-like structures (palpi) are attached to the lower jaw-like structures (maxillae). The last segment of each maxillary palp is pointed.

The legs are reddish-black. The forward, middle, and back legs each have 5 end segments (tarsi). They appear as 4 segments because the minute 4th segment is concealed by the enlarged 3rd segment.

The male is similar to the female but smaller (not including the antennae). The elytra do not have patches of white hairs.

 
     
 

Size

 
 

¾ to 11 16

 
     
 

Similar Species

 
  Asian longhorned beetle (Anoplophora glabripennis) scutellum is black, not covered with white hairs. The white markings on the elytra of the female are much more conspicuous. The female has conspicuous white markings on the antennae.  
     
 
Habitat
 
 

Fire-damaged coniferous and mixed forests

 
     
 
Biology
 
 

Season

 
 

June to September

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

Adults emerge in June or later depending on the weather. After mating, the female chooses a suitable location away from direct sunlight on the side or bottom of a dead or dying host tree or log. She then chews a slit into the bark and lays one or sometimes more eggs in the slit. Egg laying begins in early June and continues to early September.

The egg hatches in 9 to 14 days. Within three days the larva tunnels into the cambium where it feeds until mid- or late summer. It then tunnels into the wood where it overwinters. In the spring it continues tunnelling, usually turning back toward the surface and creating a U-shaped tunnel. When it nears the surface it creates a pupal cell and plugs the end of the tunnel. It overwinters as a prepupa. In late May or June of the following spring the larva pupates. Two weeks later the adult emerges.

In northern Minnesota this cycle requires two years. Farther south it may take only one year.

 
     
 

Larva Food

 
 

Dead or dying wood of conifers, especially eastern white pine, but also red pine, jack pine, balsam fir, white spruce, and black spruce, and occasionally tamarack.

 
     
 

Adult Food

 
 

Needles and the tender bark of twigs of conifers.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7, 24, 29, 30, 72.

 
  8/1/2022      
         
 

Occurrence

 
 

Common and widespread

 
         
 
Taxonomy
 
 

Order

Coleoptera (beetles)  
 

Suborder

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

Infraorder

Cucujiformia  
 

Superfamily

Chrysomeloidea (long-horned and allies)  
 

Family

Cerambycidae (longhorn beetles)  
 

Subfamily

Lamiinae (flat-faced longhorn beetles)  
 

Tribe

Lamiini  
 

Genus

Monochamus (sawyer beetles)  
  Species Monochamus scutellatus (white-spotted sawyer)  
       
 

There are two subspecies on Monochamus scutellatus. Only the nominate subspecies, Monochamus scutellatus scutellatus, occurs east of the Rocky Mountains.

 
       
 

Synonyms

 
 

Monochamus resutor

 
       
 

Common Names

 
 

spruce bug

spruce sawyer

whitespotted sawyer

white-spotted sawyer

white-spotted sawyer beetle

 

 

 

 

 

 

 

 

 

Glossary

Cambium

A thin layer of soft growing tissue composed of unspecialized cells in the stems of plants. It provides new xylem to the inside and new phloem to the outside.

 

Elytra

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

 

Maxillae

Paired mouth structures of arthropods located immediately behind the mandible and used for tasting and manipulating food. “Under-jaws”.

 

Palp

Short for pedipalp. A segmented, finger-like process of an arthropod; one is attached to each maxilla and two are attached to the labium. They function as sense organs in spiders and insects, and as weapons in scorpions.

 

Pronotum

The exoskeletal plate on the upper side of the first segment of the thorax of an insect.

 

Scutellum

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.

 

Tarsus

The last two to five sections of an insect’s leg, attached to the tibia; the foot.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 
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Alfredo Colon

 
    white-spotted sawyer   white-spotted sawyer  
           
    white-spotted sawyer      
 

Mary Katherine May

 
    white-spotted sawyer      
 

Bobbi Johnson

 
    white-spotted sawyer      
 

Christine A. Abell

 
    white-spotted sawyer   white-spotted sawyer  
 

Luciearl

 
    white-spotted sawyer      
           
 

Found on my screen door.

 
    white-spotted sawyer      
 

Jasmine

 
    white-spotted sawyer      
 

Rick Freitag

 
    whitespotted sawyer      
 

Bill Reynolds

 
 

They bite!

 
    whitespotted sawyer      
           
 
MinnesotaSeasons.com Photos
 
    whitespotted sawyer   whitespotted sawyer  

 

Camera

     
 
Slideshows
 
Whitespotted Sawyer (Monochamus scutellatus)
Andree Reno Sanborn
  Whitespotted Sawyer (Monochamus scutellatus)  
Monochamus scutellatus (White-spotted Sawyer)
Allen Chartier
  Monochamus scutellatus (White-spotted Sawyer)  

 

slideshow

       
 
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Nathaniel Morris

 
  white spotted sawyer 01
Jul 26, 2022
 
   
 
About

whitespotted sawyer (Monochamus scutellatus scutellatus)
Augusta County Virginia
he likes to talk alot
Video by Nathaniel Morris
http://www.minnesotaseasons.com/Insects/white-spotted_sawyer.html

   
       
 
Other Videos
 
  White-spotted Sawyer Beetle (Cerambycidae: Monochamus scutellatus) on the Move!
Carl Barrentine
 
   
 
About

Uploaded on Jul 3, 2011

Photographed at Nisswa, Minnesota (01 July 2010). Thank you to 'v belov' (@Bugguide.net) for confirming the identity of this specimen!

 
  Monochamus scutellatus
wetvideocamera
 
   
 
About

Published on Dec 7, 2013

White-spotted Sawyer - A member of the Cerambicydae Family of Long-horned Beetles. Seen on a picnic table at Lightning Lakes in Manning Park, BC. I was sitting there when this critter came in for a landing.

 

 

Camcorder

 
 
Visitor Sightings
 
           
 

Report a sighting of this insect.

 
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Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.
 
  Nathaniel Morris
7/25/2022

Location: Augusta County Virginia

he likes to talk alot

   
  Kelly
6/13/2022

Location: Potassium St., Ramsey, MN

   
 

Mary Katherine May
4/3/2022

Location: Littlefork, Koochiching County MN

whitespotted sawyer

 
  Alfredo Colon
7/8/2021

Location: Woodbury, Minnesota

whitespotted sawyer

 
  Christine A. Abell
8/7/2020

Location: Wrenshall, MN

whitespotted sawyer  
  Judy Schink
6/30/2020

Location: Aurora, MN    St. Louis County

Are these really harmful to trees?  This one flew into the house.  We captured and released.  However, with trees lining the streets and being next to a city park with many pine trees, we are wondering if we should have disposed it instead.

 
  John Valo
6/30/2020

These beetles are found especially in forested areas that have been recently burned. The female lays eggs in dead or dying wood. The damage is a concern to the logging industry because the larvae tunnels damage the wood. This boring beetle is not a threat to healthy trees.

 
  Luciearl
5/26/2020

Location: Cass County

Found on my screen door.

whitespotted sawyer  
  HaawZ71
7/10, 7/13, & 7/15/2019

Location: Bemidji, Minnesota

   
  Amanda
6/30/2019

Location: Park Rapids, MN

   
  Jasmine
6/16/2019

Location: Monticello, MN

whitespotted sawyer  
  Luciearl
6/2/2018

Location: Cass County

whitespotted sawyer  
  Rick Freitag
7/19/2015

Location: Duluth MN

whitespotted sawyer  
  Bill Reynolds
7/18/2003

Location: St Louis Co MN

They bite!

whitespotted sawyer  
           
 
MinnesotaSeasons.com Sightings
 
   

 

 

Binoculars


Created 2/2/2014

Last Updated:

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