half-wing

(Phigalia titea)

half-wing
Photo by Alfredo Colon
  Hodges #

6658

 
 
Conservation Status
  IUCN Red List

not listed

 
  NatureServe

NNR - Unranked

SNR - Unranked

 
  Minnesota

not listed

 
           
 
Description
 
 

Half-wing is a medium-sized, early season, typical geometer moth. It occurs in the United States and southern Canada east of the Great Plains. Adults are are among the first moths to be seen flying in early spring. They are found from late March to late May in forests and woodlands. Larvae feed on young leaves of trees, including American basswood, American elm, apple, birch, hickory, maple, oak, and poplar; and on woody shrubs, including blueberry, cranberry, and ninebark. They can defoliate small areas of a forest, and are considered a pest. However, they do not occur in numbers large enough to do serious damage.

The antennae have 46 to 48 segments. On the male they are feather-like with two branches on each segment (bipectinate). On the female they are thread-like.

The abdomen is slender. The upper surface is covered with flattened, elongated, deeply forked, hair-like scales.

Adult males have large wings in comparison to their light-weight bodies. The forewing length is to (15 to 22 mm) and the wingspan is 1316 to 1916 (30 to 40 mm). Most males have pale gray forewings with heavy, gray, grayish-brown, or brownish-black (dark) lines and a variable peppering of dark scales. There is no discal spot. The antemedial (AM) line is wavy and is shadowed by a broad dark basal band. The median line is broad and straight. The postmedial (PM) line is wavy, slightly scalloped or toothed, and shadowed with a broad dark band in the subterminal area. The PM line has a deep bend that approaches but does not touch the median line. The subterminal (ST) line is represented by a broken band of dark shading. The terminal line is thin. The fringe is the same color as the wing. The hindwing is similar to the forewing but lacks the dark bands and the median line is incomplete. Females do not fly. They have all four wings but they are very small and non-functional. The forewing length is just (3 to 4 mm).

The legs are pale gray or grayish-brown and are covered with a variable amount of scattered dark scales. The fourth segment (tibia) of the front leg does not have a spine at the tip. On the hind leg there are two pairs of spurs on the tibia.

A dark (melanistic) form is not uncommon. On these moths the base color of the wings is dark brown to almost black and the lines and veins are black.

The caterpillar, called spiny looper, is light bluish-gray and up to 1 (3.5 cm) long. It has numerous black pinstripes running the length of the body. There is an orange stripe bordered with thin black lines on each side close to the middle (addorsal). There is also an orange patch on each side of every abdominal segment around the breathing pore (spiracle). On the second, third, and eighth abdominal segments there is a raised ward below and behind each spiracle. Stiff, bristle-like hairs (setae) on the upperside of each abdominal segment rise from black pimple-like bases. The head has many small, scattered, black spots.

 
     
 

Size

 
 

Male forewing length: to (15 to 22 mm)

Female forewing length: (3 to 4 mm)

Male wingspan: 1316 to 1916 (30 to 40 mm)

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Forests and woodlands

 
     
 
Biology
 
 

Season

 
 

One generation per year: Late March to late May.

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

The female deposits eggs in crevices in bark. When the eggs hatch, the caterpillar crawls or floats about on a silk thread (balloons) to find suitable foliage. Caterpillars feed for about a month and a half, passing through five stages (instars). They overwinter in the soil as pupa. Adults emerge from late May to late April.

 
     
 

Larva Hosts

 
 

American basswood, American elm, apple, birch, hickory, maple, oak, poplar, blueberry, cranberry, and ninebark.

 
     
 

Adult Food

 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

21, 24, 29, 30, 75.

 
  11/14/2021      
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
 

Order

Lepidoptera (butterflies and moths)  
 

Suborder

Glossata  
 

Infraorder

Neolepidoptera  
  Parvorder Heteroneura  
  No Rank Ditrysia  
  No Rank Obtectomera  
 

Superfamily

Geometroidea (geometrid and swallowtail moths)  
 

Family

Geometridae (geometer moths)  
 

Subfamily

Ennominae (typical geometers)  
 

Tribe

Bistonini  
 

Genus

Phigalia  
       
 

Synonyms

 
 

Apocheima titea

Deileptenia titearia

Phigalia cinctaria

Phigalia deplorans

Phigalia olivacearia mephistarua

Phigalia revocata

 
       
 

Common Names

 
 

half-wing

half-wing moth (adult)

spiny looper (caterpillar)

the half-wing

 

 

 

 

 

 

 

 

Glossary

Antemedial (AM) line

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

 

Postmedial (PM) line

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

 

Seta

A stiff, hair-like process on the outer surface of an organism. In Lepidoptera: A usually rigid bristle- or hair-like outgrowth used to sense touch. In mosses: The stalk supporting a spore-bearing capsule and supplying it with nutrients. Plural: setae.

 

Spiracle

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

 

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot). The fifth segment of a spider leg or palp.

 

Industrial melanism

The dark coloring on melanistic individuals is thought to be an adaptation to the color of the bark and lichens on the host plant. It may be an example of industrial melanism, where the insect evolves to match the soot-darkened bark of its host.

 
 
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Alfredo Colon

 
    half-wing      
           
 
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Other Videos
 
  The Half-wing Moth (Geometridae: Phigalia titea) Dosal View
Carl Barrentine
 
   
 
About

May 1, 2010

Photographed at Grand Forks, North Dakota (30 April 2010).

 
  The Half-wing (Geometridae: Phigalia titea) Adult Male
Carl Barrentine
 
   
 
About

Apr 9, 2011

Photographed at Grand Forks, North Dakota (09 April 2011).

 
  The Half-wing (Geometridae: Phigalia titea) Adult Female
Carl Barrentine
 
   
 
About

Apr 10, 2011

Photographed at Fisher, Minnesota (10 April 2010).

 
  The Half-wing Moth (Geometridae: Phigalia titea) Caterpillar on Grassblade
Carl Barrentine
 
   
 
About

Jun 16, 2010

Photographed at Turtle River State Park, North Dakota (14 June 2010). Go here to learn more about this species: http://bugguide.net/node/view/13846

 
  Half-wing Moth Caterpillar (Geometridae: Phigalia titea)
Carl Barrentine
 
   
 
About

Jun 10, 2011

Photographed at the Turtle River State Park, North Dakota (08 June 2011).

 

 

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  Alfredo Colon
5/30 to 6/1/2021

Location: Woodbury, MN

half-wing

 
           
 
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Created: 11/14/2021

Last Updated:

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