oak leaf gall midge

(Polystepha pilulae)

Conservation Status
oak leaf gall midge
  IUCN Red List

not listed

     
  NatureServe

not listed

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Oak leaf gall midge is a long-legged, 1 16 to long, mosquito-like fly (midge). The abdomen has ten segments, each covered with upper (dorsal) and lower (ventral) exoskeletal plates. On the female the seventh lower plate (sternite) is much longer than the sixth; and the eighth upper plate (tergite) is wide, strongly hardened, and laterally notched. The wings are clear, are covered with hairs, and have reduced venation. Only four veins reach the wing margin. The basal segment of the foot (tarsus) is much shorter than the second segment. The mouth parts are reduced. The large compound eyes meet at the top of the head. There are no simple eyes (ocelli). The antennae are long and have 12 segments. On the female these segments are cylindrical.

Adults are impossible to identify by appearance in the field. However, the species can easily be identified by the gall it produces. Galls appear always on the upper surface of northern pin oak, northern red oak, and possibly black oak leaves. They are hard, 1 16 to 3 16 in diameter, and irregular in shape. They are green when they first appear in the spring, soon turning red or magenta. As they age they become brown and crusty. They can be easily detached from the leaf surface.

The larva is bright orange.

 
     
 

Size

 
 

Gall: 1 16 to 3 16

 
     
 

Similar Species

 
 

Blackjack oak leaf gall midge (Polystepha globosa) forms similar spherical galls on the undersurface of the leaves of black oak and possibly other oaks in the red oak group.

 
     
 
Habitat and Hosts
 
 

Northern pin oak, northern red oak

 
     
 
Biology
 
 

Season

 
 

Autumn

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

Larvae break out of the gall in the fall and reproduce before reaching maturity.

 
     
 

Larva Hosts

 
 

Northern pin oak, northern red oak, and possibly black oak

 
     
 

Adult Food

 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7, 24, 29, 30.

 
  10/2/2020      
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
 

Order

Diptera (gnats, mosquitoes, true flies)  
 

Suborder

Nematocera (long-horned flies)  
 

Infraorder

Bibionomorpha  
 

Superfamily

Sciaroidea (fungus gnats and gall midges)  
 

Family

Cecidomyiidae (gall gnats, gall midges, cécidomyidés)  
 

Subfamily

Cecidomyiinae (gall midges)  
 

Supertribe

Asphondyliidi  
  Tribe Asphondyliini  
  Subtribe Polystephina  
 

Genus

Polystepha  
       
 

Synonyms

 
 

Cincticornia pilulae

 
       
 

Common Names

 
 

oak leaf gall

oak leaf gall midge

pin oak gall

red oak gall

 
       

 

 

 

 

 

Glossary

Gall

An abnormal growth on a plant produced in response to an insect larva, mite, bacteria, or fungus.

 

Midge

A small fly, somewhat resembling a mosquito, in one of several families in the suborder Nematocera.

 

Ocellus

Simple eye; an eye with a single lens. Plural: ocelli.

 

 

 

 

 

 
 
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2mevon

 
    oak leaf gall midge      
 

Luciearl

 
 

Galls

Bright color (not captured in photo) to these formations on oak leaves.

  oak leaf gall midge  
           
 
MinnesotaSeasons.com Photos
 
 

Leaf upperside

 
    oak leaf gall midge      
           
 

Leaf underside

 
    oak leaf gall midge   oak leaf gall midge  
           
 

Lateral veiw

 
    oak leaf gall midge      
           
 

Galls

 
    oak leaf gall midge   oak leaf gall midge  
           
    oak leaf gall midge      
           

 

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Other Videos
 
  Oak Leaf Gall Midge (Larva) - Polystepha pilulae
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About

Published on Oct 12, 2014

Oak Leaf Gall Midge (Larva) - Polystepha pilulae

Insect species: Oak Leaf Gall Midge (Larva)
Polystepha pilulae (Beutenmuller, 1892)
Diptera : Cecidomyiidae

Date: 03 OCTOBER 2014

[vado-g3 avidemux]

 
       

 

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