oak leaf gall midge

(Polystepha pilulae)

               
Conservation Status

IUCN Red List

not yet assessed

oak leaf gall midge (pilulae)

NatureServe

not listed

Minnesota

not listed

Occurrence

Common

Flight/Season

Autumn

Habitat

 

Size

Gall: 1 16 to 3 16


Identification

This 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.

 
Similar
Species

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.


Larval Hosts

Northern pin oak (Quercus ellipsoidalis), northern red oak (Quercus rubra), and possibly black oak (Quercus velutina)

 
Adult Food

 

 
Life Cycle

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

 
Behavior

 


Distribution Distribution Map  

Sources: 7, 29.


Comments

 


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)

 

No Rank:

Asphondyliidi

 

Tribe:

Asphondyliini

 

Subtribe:

Polystephina

 
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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Leaf upperside

  oak leaf gall midge (pilulae)    
       

Leaf underside

  oak leaf gall midge (pilulae)   oak leaf gall midge (pilulae)
       

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  oak leaf gall midge (pilulae)    
       

Galls

  oak leaf gall midge (pilulae)   oak leaf gall midge (pilulae)
       
  oak leaf gall midge (pilulae)    
       
       

 

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  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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