elm sawfly

(Cimbex americana)

Conservation Status
elm sawfly
  IUCN Red List

not listed

     
  NatureServe

not listed

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Elm sawfly large, colorful sawfly is the largest sawfly in North America.

The body is bluish-black, stout, and almost parallel sided. The base of the abdomen is broadly attached to the thorax, not a slender wasp-like waist.

The thorax is black and hairless, with a large yellowish-white spot on the upper (dorsal) surface. On the male the spot is distinct and conspicuous. On the female it is faint.

The male abdomen may be all black, reddish-brown to black, or mostly reddish brown. The female abdomen is all black and has 3 or 4 yellowish-white spots on the sides of the abdomen. The ovipositor of the female is conspicuous and saw-like, an attribute common to all sawflies.

The head is black and squarish in front. The antennae are orange with 4 to 7 segments and are slightly expanded (clubbed) at the tip.

There are two pairs of transparent, smoky brown wings.

The legs are bi-colored or tri-colored. The third and fourth segments (femur and tibia respectively) may be black, reddish-brown, or a combination of both. The tibia of the front leg has 2 spurs at the tip. The femur of the hind legs are especially robust. The five foot segments (tarsi) are yellow.

The larvae resemble caterpillars but that name is reserved for the larvae of moths and butterflies. The body is cylindrical in shape, pale green or yellow, and warty. The head is smooth, distinctly separated from the thorax, and has no cleavage line. The eyes are black. A black longitudinal stripe extends from the thorax behind the head to the eighth abdominal segment. The thorax has 3 pairs of well-developed true legs. The abdomen has small black spots surrounding the breathing pores (spiracles). There are 7 pairs of false legs (prolegs) attached to the abdomen, unlike true caterpillars, which have only 5 pairs.

 
     
 

Size

 
 

Total Length: 11 16 to 1

Wingspan: 1¾

Larva: 1½ to 2

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Woodlands

 
     
 
Biology
 
 

Season

 
 

One generation per year: mid-May to mid-August

 
     
 

Behavior

 
 

Larvae feed with the rear of their abdomen coiled around a twig. They rest in a coiled position. They rarely cause serious damage but can cause sporadic defoliation. They are not considered forest pests.

Adults use their powerful mandibles to cut horizontal gashes in the bark of twigs and small branchlets in order to feed on sap. They sometimes girdle the limb, causing it to die.

 
     
 

Life Cycle

 
 

The female uses her saw-like ovipositor to cut a slit on the underside of leaves and deposit eggs. The eggs hatch in 7 to 10 days and the larvae feed on leaves. In late summer or early fall the larvae drop to the ground and spin cocoons in the leaf litter at the base of the host tree. They overwinter in the cocoons, pupate in the spring, and emerge as adults in May or June. Some larvae spend two winters in the cocoon before pupating.

 
     
 

Larva Food

 
 

Leaves of elm, maple, birch, willow, and American basswood.

 
     
 

Adult Food

 
 

Tree sap of mostly elm and willow, but also other hardwoods including maple, birch, and American basswood.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7, 24, 29, 30.

 
  7/27/2020      
         
 

Occurrence

 
 

Widespread

 
         
 
Taxonomy
 
 

Order

Hymenoptera (ants, bees, wasps, and sawflies)  
 

Suborder

Symphyta (horntails, sawflies)  
 

Superfamily

Tenthredinoidea (sawflies)  
 

Family

Cimbicidae (cimbicid sawflies)  
 

Genus

Cimbex  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

elm sawfly

 
       

 

 

 

 

 

Glossary

Femur

On insects and arachnids, the third, largest, most robust segment of the leg, coming immediately before the tibia. On humans, the thigh bone.

 

Ovipositor

A long needle-like tube on the abdomens of some female insects, used to inject eggs into soil or plant stems.

 

Proleg

A fleshy structure on the abdomen of some insect larvae that functions as a leg, but lacks the five segments of a true insect leg.

 

Spiracle

A small opening on the surface of an insect through which the insect breathes.

 

Tarsus

The last two to five subdivisions of an insect’s leg, attached to the tibia; the foot. Plural: tarsi.

 

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot).

 

 

 

 

 

 
 
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Melissa K.

 
    elm sawfly      
 

Jason Crowson

 
 

Found in our kids small pool in yard

 
    elm sawfly   elm sawfly  
           
    elm sawfly      
 

Susan C.

 
 

the pink version!

 
    elm sawfly      
 

Tim Lantz

 
 

Larval state

 
    elm sawfly      
 

Courtney Walker

 
    elm sawfly   elm sawfly  
           
 
MinnesotaSeasons.com Photos
 
    elm sawfly   elm sawfly  
           
    elm sawfly   elm sawfly  
           

 

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Visitor Videos
 
       
 

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Other Videos
 
  Elm Sawfly Larva (Cimbicidae: Cimbex americana) Defensive Posture
Carl Barrentine
 
   
 
About

Uploaded on Sep 5, 2011

Photographed at the Turtle River State Park, North Dakota (05 September 2011).

 
  Elm Sawfly Larva (Cimbicidae: Cimbex americana) Locomotion
Carl Barrentine
 
   
 
About

Uploaded on Sep 11, 2011

Photographed at the Turtle River State Park, North Dakota (11 September 2011).

 
  Elm sawfly catapillar
nisbet819
 
   
 
About

Published on Jul 31, 2013

:p

 
       

 

Camcorder

 
 
Visitor Sightings
 
           
 

Report a sighting of this insect.

 
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  Pamela
7/29/2020

Location: Proctor, MN

I saw the yellow ‘caterpillar’.   Are these bad for our trees?

   
  John Valo
7/30/2020

Since they feed late in the season, the damage they do is rarely serious.

 
  Melissa K.
6/6/2020

Location: Rice, MN (Benton County)

elm sawfly  
  Jason Crowson
6/4/2020

Location: Lindstrom / Chisago County

Found in our kids small pool in yard

elm sawfly  
  Susan C.
8/15/2019

Location: Eveleth MN

the pink version!

elm sawfly  
  Tim Lantz
7/13/2019

Location: Bearhead Lake State Park

Larval state

elm sawfly  
  Courtney Walker
7/16/2017

Location: Houston, MN

elm sawfly  
           
 
MinnesotaSeasons.com Sightings
 
   

 

 

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