armyworm moth

(Mythimna unipuncta)

               
Hodges #

10438

armyworm

 

Conservation Status

IUCN Red List

not listed

NatureServe

N5 - Secure

Minnesota

not listed

Occurrence

Common, sometimes abundant

Flight/Season

Two or three generations per year: March to November

Habitat

Fields, meadows, gardens, and agricultural crops

Size

Total Length: ¾ to 1 (20 to 25 mm)

Wingspan: 1 to 1 (35 to 47 mm)

          Photo by Alfredo Colon
 
Identification

Armyworm moth, also called true armyworm and the white speck. is a migratory wainscot moth. It is medium-sized for a moth, large for a wainscot moth. It occurs in Europe, northern Africa, Iceland, North America, Central America, and northern South America. It is common throughout the United States and Canada, common and sometimes abundant in Minnesota. It does not survive cold winters. Adults migrate south in the fall and a later generation disperses north in the spring. Adults are found in Minnesota from March to November. Larvae (caterpillars) feed on leaves and sometimes seed heads of mostly grains and other grasses in the family Poaceae, but also many broadleaf plants close to their infestations. They are often a serious agricultural pest, especially on wheat and corn.

Adults are ¾ to 1 (20 to 25 mm) long and have a wingspan of 1 to 1 (35 to 47 mm). The forewing is long and somewhat pointed at the tip (apex). It is mostly tan with a peppering of dark scales. There is a gray line at the wing tip that extends diagonally inward less than half way across the wing, then becomes a line of black dots that continues to the inner margin. On some individuals, the triangular area beyond the gray line is tinted grayish. The discal cell is tinted reddish-orange from the base to the gray line. There are three noticeable horizontal lines; the antemedial (AM) line between the basal and median areas; the postmedial (PM) line that separates the median area from the postmedial area; and the terminal line at the outer margin. On some individuals, the AM line consists of a row of gray dots, one on each vein. On others, the AM line is absent. The PM line is a smoothly curved row of gray spots, one on each vein. The terminal line is a straight row of small gray spots. There is a circular spot in the median area (orbicular spot) and a kidney-shaped spot at the end of the discal cell (reniform spot). Both spots have broad pale border with a small center the same color as the background. On some individuals both spots inconspicuous or absent. There is no wedge-shaped spot near the inner margin (claviform spot). The cubital (Cu) vein is often white. There is always a small but conspicuous white spot at the outer (distal) end of the Cu vein), and often a small gray area just beyond the spot.

The hindwings are grayish-brown, pale at the base grading to dark at the tip. The veins and discal spot are dark.

The head and thorax are a similar color to the forewings but darker. On the upper side of the thorax there is a tuft of hairs that is dark just behind the head, otherwise the same color as the forewing. The antennae are threadlike on both the male and the female. The eyes are covered with fine hairs. The pair of small, finger-like processes (labial palps) curving up from the lower part of the head are long, extending at least to the middle of the face.

The caterpillar is up to 2 long.

 
Similar
Species

 

 
Larval Food

Leaves and sometimes seed heads of mostly grains and other grasses in the family Poaceae, but also many broadleaf plants close to their infestations.

 
Adult Food

Flower nectar

 
Life Cycle

 

 
Behavior

Adults are active at night and will come to light.

After defoliating a stand of plants, the larvae will move as a group to a nearby stand and resume feeding.

 
Distribution Distribution Map  

Sources: 21, 24, 29, 30, 71, 75.

 
Comments

 

 
Taxonomy

Order:

Lepidoptera (butterflies and moths)

 

Suborder:

Glossata

 

Infraorder:

Neolepidoptera

 

Parvorder:

Heteroneura

 

No Rank:

Ditrysia

 

No Rank:

Obtectomera

 

Superfamily:

Noctuoidea (noctuid moths)

 

Family:

Noctuidae (owlet moths)

 

Subfamily:

Noctuinae (cutworms or dart moths)

 

Tribe:

Leucaniini (Wainscots)

 

Genus:

Mythimna

 
Synonyms

Leucania antica

Leucania extranea

Leucania unipuncta

Pseudaletia unipuncta

 
Common
Names

armyworm (caterpillar)

armyworm moth (adult)

common armyworm

rice armyworm

 

true armyworm

the one-spot

the white-speck

white-speck moth

 

 

 

 

 

 

 

Glossary

Antemedial (AM) line

A thin line separating the basal area and the median area of the forewing of Lepidoptera.

 

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 weapons in scorpions. Plural: palpi.

 

Orbicular spot

A circular spot or outline in the inner median area on the forewing of many moths in the Noctuidae family.

 

Postmedial (PM) line

A thin line separating the median area and the postmedial area of the forewing of Lepidoptera.

 

Reniform spot

A kidney-shaped spot or outline in the outer median area near the costal margin on the forewing of many moths of the Noctuidae family.

 

 

 

 

 

       
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Alfredo Colon
       
  armyworm    
       
MinnesotaSeasons.com Photos
   
       
       
       

 

Camera

     
Slideshows
   
  Armyworm - Hodges#10438 (Mythimna unipuncta)
Andree Reno Sanborn
 
  Armyworm - Hodges#10438 (Mythimna unipuncta)  

 

slideshow

       
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Other Videos
 
  Armyworm Moth (Noctuidae: Mythimna unipuncta) Moved by Ant
Carl Barrentine
 
   
 
About

Aug 5, 2010

Photographed at Turtle River State Park, North Dakota (04 August 2010).

   
       
  Mythimna unipuncta
ATLnature
 
   
 
About

Mar 5, 2019

   
       

 

Camcorder

         
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Alfredo Colon
Summer 2018

Location: Woodbury, Minnesota

armyworm


     
     
 
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Created: 12/28/2019

Last Updated:

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