oak besma

(Besma quercivoraria)

oak besma
Photo by Alfredo Colon
  Hodges #

6885

 
 
Conservation Status
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

SNR - Unranked

     
  Minnesota

not listed

     
           
 
Description
 
 

Oak besma is a medium-sized to large typical geometer moth. It occurs throughout the United States except for California, and across southern Canada. It is most common east of the Great Plains. It is common in Minnesota. Adults are found from early May to late August in deciduous and mixed woodlands. Larvae feed on oak, birch, elm, poplar, willow, and white spruce.

Adults have slender bodies and relatively large wings, with a wingspan of 1116 to 1 (27 to 41 mm).

The antennae on the female are slender and thread-like. On the male the antennae are branched, feather-like, on both sides (bipectinate).

The wings are large and thin. Each wing has a projection on the outer margin, giving the moth a scalloped appearance. The background color is variable; yellow, pale tan, or light reddish-brown on the male, paler on the female. All wings are have dark veins and dark lines, and are peppered with dark scales. On the forewings there is a curved antemedial (AM) line and a scalloped subterminal (ST) line. The AM line extends to the forward (costal) margin but often ends before the inner margin. It is always dark and distinct. The ST line extends to the (costal margin but always ends well before the inner margin. It is usually faint. On all wings there is a distinct postmedial (PM) line that always extends from the costal to the inner margin. It forms a continuous, straight or slightly scalloped line across all four wings. There is usually a small black spot (discal spot) on the inner half of all wings. The discal spots are “almost always present” on the forewing and hindwing. On the female there is sometimes a dark smudge on the outer half of the forewing near the inner margin. On the male there is often dark shading beyond the PM line and along the AM line. On both sexes the scales at the base of the fringe are dark, creating a fine dark line on the outer margin.

The caterpillar, called a looper, is twig-like and up to 1916 (4 cm) long. The ground color is “exceedingly variable.” Early stages (instars) are green and do not have any wart-like bumps. Middle instars usually have some brown. The second segment of the thorax (T2) has a pair of dark, wart-like bumps on top (subdorsal). On the third abdominal segment (A3) there are similar subdorsal warts and a wart on each side. There are smaller warts on the side and near the underside (subventral) of A2. There is also a pair of small subdorsal warts on A1, A5, A6, and A8, and these may be well or poorly developed. The warts are usually reddish or blackish. Late instars may be brown, tan, or gray, or a combination of these, and the bumps are larger. There are 3 pairs of legs on the thorax, one on each segment, and just 2 pairs of leg-like structures (prolegs) on the abdomen, one pair on A6 and one pair on A10. The head is brown and black. Mature caterpillars are active from June onward.

 
     
 

Size

 
 

Wingspan: 1116 to 1 (27 to 41 mm)

 
     
 

Similar Species

 
  Straw besma (Besma endropiaria) is paler overall and has lighter markings. There is no discal spot. The fringe scales are the same color as the wing background.  
     
 
Habitat
 
 

Deciduous and mixed woodlands and forests

 
     
 
Biology
 
 

Season

 
 

Two generations per year. Early May to late August.

 
     
 

Behavior

 
 

Adults rest with their wings spread flat. They are active at night and will come to light.

 
     
 

Life Cycle

 
 

The pupa overwinters.

 
     
 

Larva Hosts

 
 

Oak, birch, elm, poplar, willow, and white spruce

 
     
 

Adult Food

 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

21, 24, 27, 29, 30, 71, 72, 75, 82.

 
  12/12/2020      
         
 

Occurrence

 
 

Common in Minnesota

 
         
 
Taxonomy
 
 

Order

Lepidoptera (butterflies and moths)  
 

Suborder

Glossata  
 

Infraorder

Neolepidoptera  
  Parvorder Heteroneura  
  No Rank Ditrysia  
  No Rank Obtectomera  
 

Superfamily

Geometroidea (inchworm moths)  
 

Family

Geometridae (geometer moths)  
 

Subfamily

Ennominae (typical geometers)  
 

Tribe

Ourapterygini  
 

Genus

Besma  
       
 

Synonyms

 
 

Meatnema aeliaria

 
       
 

Common Names

 
 

oak besma

 
       

 

 

 

 

 

 

 

Glossary

Costal margin

The leading edge of the forewing of insects.

 

Instar

The developmental stage of arthropods between each molt; in insects, the developmental stage of the larvae or nymph.

 

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.

 

 

 

 

 

       
Visitor Photos
   

Share your photo of this moth.

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

       
Alfredo Colon
       
  oak besma    
       
MinnesotaSeasons.com Photos
   
       
       
       

 

Camera

     
Slideshows
   
  Oak Besma - Hodges#6885 (Besma quercivoraria)
Andree Reno Sanborn
 
  Oak Besma - Hodges#6885 (Besma quercivoraria)  
     

 

slideshow

       
Visitor Videos
   

Share your video of this moth.

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

       
       
       
Other Videos
 
  besma quercivoraria larvae
anupama jadhav
 
   
 
About

Mar 8, 2016

besma quercivoraria larvae on basil

   
       

 

Camcorder

         
Visitor Sightings
   

Report a sighting of this moth.

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.

Alfredo Colon
8/9/2019

Location: Woodbury, MN

oak besma


 
         
MinnesotaSeasons.com Sightings
         

 

 

 

Binoculars


Created: 12/12/2020

Last Updated:

About Us | Privacy Policy | Contact Us | © 2021 MinnesotaSeasons.com. All rights reserved.