Callirhytis maxima, new species

Host. — Quercus alba Linnaeus, Quercus macrocarpa Michaux, Quercus bicolor Willdenow, Quercus prinus Linnaeus.

Gall. — A large rounded mass, 90 by 50 by 50 mm. or smaller, growing out from side of one of main roots at base of tree or stump just below surface of the ground. Surface uneven but smooth, brown. When mature the interior is soft and easily cut or crumbled with the fingers, and might be taken for a piece of well-rotted wood until the numerous hard shell-like thin-walled brown cells are noticed imbedded in the whitish matrix. When the moisture is dried out the galls are as light as cork.

Type locality. — Fort Sheridan, Illinois.

Biology. — On October 4, 1914, galls were found on Q. macrocarpa with adults ready to emerge; others with the substance of the gall firmer contained full-grown larvae, others less than half an inch in diameter were fleshy with larval cavities barely visible, suggesting that the gall takes three years to mature, or else two, and the larvae in some do not transform the second fall but hold over until the third. At Winnetka, Illinois, October 30, some galls contained adults and others were very small. On November 1, immature galls were found at New Lenox, Illinois. On April 24, 1915, a small gall was found on Quercus alba from which adults were issuing. They were smaller, averaging 3.4 mm., but otherwise similar. Found gall at Highland Park, Illinois, on May 12, 1917, looking as if the adults had but recently issued; another at Fort Sheridan May 25 showed exit holes where all the adults had escaped. Collected a fine gall on Quercus alba May 6, 1914, on Plummer Island, Maryland. Adults evidently transform in autumn and emerge the next spring in late April or early May. A single fly of what seemed to be this species was noted in the stomach contents of blue-headed vireo (Lanivireo solitarius (Wilson) at Washington, District of Columbia, on April 15. A single old gall of this species was found on roots of Quercus prinus in September, 1919, at East Falls Church, Virginia, and another at Plummer Island, Maryland.

Holocynips maxima

Quercus alba, bicolor, macrocarpa, prinus [montana]
"Root" galls
Rounded, many-celled mass, up to 50 by 95 mm growing out of side of big roots in the fall.

Quercus stellata
"Root" galls
Like Holocynips maxima. A disintegrated gall only seen. AR

[Photo caption]
On Q alba. Also on Q prinus, bicolor, macrocarpa. Gall probably takes two or perhaps three years to develop. Transformation takes place in the fall and emergence the next spring in late April or early May. They have been taken ovipositing in buds of Q alba on Apr 6, 13, 19, 20, 23 (DC).