INSECTS AFFECTING PARK AND WOODLAND TREES 625 



Lobed oak gall. Cviii/'s s/i-obilaiia Osten SackcMi. A larj^-e, oval body 

 consistiiii:^ of a number of wccit^e-shapecl parts closely packed too^ether with 

 their pointed extremities attached to the twig, occurs on swamp white oak 

 [pi. 48, fig. 3 1. Each of these wedgelike structures is hard, corky, and 

 contains a larva in the central cell. It is not common. 



Large oak apple. Aviphiholips confliientus Harr. This is one of our 

 common oak galls. It is nearly globular in shape, greenish or brown in 

 color dependent on its age, and its interior is filled with a spongy mass in 

 the center of which is a single larval cell. This species is occasionally 

 quite abundant on trees, as may be seen by reference to plate 50, figure i, 

 though it cannot be considered injurious. Mr. Beutenmuller states that a 

 certain number of these galls produce both males and females in June and 

 others females in October or the following spring. These latter are merely 

 a dimorphic form. 



'Larger empty oak apple. Ai)ipliiholips inanis Osten Sacken. A 

 globular gall closely resembling the oak or May apple, A. c o n f 1 u e n t u s 

 Harr., occurs on the leaves of .scarlet and red oak. It is much like the 

 preceding in general appearance, though considerably smaller and may be at 

 once recognized by the nearly empty interior, the small larval cell being 

 held in position by numerous radiating filaments. 



Black scrub oak gall. Aiiiphibo/ips ilicifoliac Bass. Elongate, fusiform 

 galls tapering at both ends, with the ape.x more slender and frequently 

 slightly curved, occurs on the leaves and petioles of dwarf and scrub oak. 

 It is about 1 1/^ inches long, half that in diameter, and contains an elongated 

 kernel held in position by radiating fibers. It is green and soft in summer, 

 turning brown and becoming brittle on the approach of winter [pi. 50, 

 fig. 2]. 



Oak leaf apple. Amine us singular is Bass. A globular, smooth, green 

 gall from '4 to y'l inch in diameter, occurs rather commonly on the leaves 

 of red oak. This gall is first green and succulent, turning brown and 

 becoming brittle later in the season. It contains a central oblong cell held 

 in place by radiating fibers. 



Oak wool gall. Aiidricus lana Fitch. The white or buff-colored 

 woolly masses composing this gall, occur on the underside of the principal 

 veins of white oak leaves. Within it is composed of numerous small larval 

 cells closely crowded together and attached by their lower ends to the vein 

 of the leaf. It is recorded by Beutenmuller as common in the vicinity of 

 New York. 



Oak leafstalk gall. Andricus petiolicola Bass. These irregularly 

 rounded or fusiform, hard, woody enlargements at the base of the leaf con- 

 tain many cells. The full grown galls are about 3/j^ inch in diameter, 

 green in summer, brown in winter and common on several oaks. 



