Neuroterus washingtonensis, bisexual generation

[see paper for photo, figure 16 on page 11 of the pdf]

Gall. Irregular swellings on undersides of principal leaf veins, usually on young subterminal leaves; on trees of any size or age, but seldom on very young trees or next to the ground; more common in relatively open sunny exposures. The upper side of the leaf is contorted and reddish. The polythalamous galls contain from 4 to 85 cells, oriented towards the upper surface of the leaf, and vary in size from 7 to 55 mm, sometimes over the entire leaf length; they may be single, multiple or confluent. Occasionally more than one leaf is involved if the gall develops quickly on terminal growth. Many galls may occur over a relatively small area of a tree. Young galls are firm and white inside, green outside, becoming progressively paler and redder, finally becoming brown and hard after the insects have emerged. Adults emerge on the topside of the leaf in early summer, usually from individual exit holes. The galls persist long after the leaf parts weather away.

Adults of the bisexual generation emerge during late June. The polythalamous galls usually contain both males and females.

Neuroterus washingtonensis

Quercus garryana
Leaf galls, integral
Fig 169. Abrupt, fleshy thickening along midrib and main veins on underside of leaf, green or reddish. May-June.

Fig 169. On Q.garryana. Fleshy when young. The adults began to emerge July 7; all out by July 51(Friday Harbor, Wash.).

Range:
Northern CA, OR, WA

Neuroterus washingtonensis

This cynipid wasp induces integral, polythalamous galls on the midrib and lateral leaf veins of Oregon oak. These spring, green, abrupt swellings are most noticeable on the underside of leaves.

Host:
Quercus garryana

Neuroterus quercicola variety washingtonensis
bisexual form

A rather large vein swelling involving and deforming more or less of the blade; of indefinite shape; green, succulent when fresh, drying brown and rather hard, without much shrivelling; up to 35. mm. in length and 15. mm. in diameter. On leaves of Quercus garryana.

Range:
OR, WA

Weld's galls, collected on July 2, 1911, gave adults July 30. This is considerably later than the March and April emergence of variety pacificus further south, and shows the considerable dependence of cynipid development upon the development of the host.

The above descriptions are made from paratypes. The insect differs only slightly from pacificus, but has not gone the way of the usual synonomy. The gall is very much like that of pad ficus on Q. Douglasii. It is possible that the aments of garryana will show galls of variety washingtonensis similar to the ament galls of pacificus on Q. lobata. The alternate generation of this insect may be either a similar leaf swelling, a woody stem swelling, or a cell in an acorn cup, and I have collected the latter gall at Ashland, Oregon.