Woolly Oak Gall Wasp
Location: Calgary, AB
Date: Sept.  24,  2012
      Photo 1

Galls of the asexual generation of the oak-galling cynipid Andricus ignotus

Common Name:  Woolly Oak Gall Wasp, Cynipid Gall Wasp

Latin Name:  Andricus ignotus Bassett 1900
                        (S. Digweed, det.)

Length:  ~2.5 mm

Range:  Wherever Bur Oak is present

Habitat:  Various

Time of year seen:  Adults: March to April, Galls: Summer to Fall

Hosts: Bur Oak & other Members of the White Oak Group

Other: The asexual generation of the oak-gallling cynipid wasp A. ignotus forms elongate woolly growths (galls) along the veins on the underside of leaves on trees in the white oak group (in Alberta typically Bur Oak).  Color variations of the galls range from white to red with some having a striped appearance.  The woolly material covers the small feeding cells of these minute insects.  Adult wasps emerge early in the spring and oviposit their eggs in the buds of oaks.  As the season progresses the galls form and are shed with the leaves in the fall to over winter. This species of gall wasp is commonly attacked by parasitoids in the family Eulophidae.  The galls can be common and have no significant effect on the tree. (Digweed, S.; Hahn, J (U of M)


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