Callirhytis rugulosa

Quercus coccinea, rubra, velutina
Bud galls
Ovate, 7-10 mm long, ridged, with a knot of reflexed hairs at apex, stellate hairs on surface, wall thin, from weak lateral buds, single or in cluster, dropping in April-May.

[Photo caption]
On Q coccinea. Also on Q velutina. Galls drop in May. Some collected May 19, 1917 gave adults May 16, 1918 (IL). Adults emerged Mar 20, 29 (DC).

Andricus rugulosus, sp. nov.

Gall. — Singly or in clusters of two to about eight, on the trunks of young trees or along the stems of very young shoots of red and black oaks (Quercus rubra and Quercus velutina) late in April until early in May (8th), when the leaves begin to develop. Monothalamous. Ovate or bud-like, somewhat rough and longitudinally ribbed. Bluntly pointed at the apex. Soft, fleshy and green when fresh, often tinged with red. Hollow inside. When mature they drop to the ground, and when old they turn brown and become thin-shelled, with a large chamber inside. Length, 5-6 mm.; width, 3-3.25 mm.

Habitat. — New Jersey (Fort Lee district) ; New York (Van Courtlandt Park).

The perfect insect reaches maturity late in October, but does not emerge from the gall until April in the year following. The species is closely allied to Andricus (Trisolenia) saltatus Ashm. and punctatus Ashm. The gall exudes a honey-like liquid, which is greedily partaken by ants, and, like A. saltatus has the power of jumping, due to the contraction and sudden relaxation of the larva within.