38 INSECT-GALLS OF THE VICINITY OF NEW YORK CITY 



somewhat resembling a tomato in shape. Inside it is hollow and filled with 

 lice. Yellowish green, tinged with red. On under side of leaf of smooth 

 sumac (Rhus glabra) and stag-horn stunac {Rhus typhina). Common. 



85. Poplar Stem Gall {Pemphigus popidicaulis Fitch). — Irregularly globu- 

 lar, with a mouth-like orifice at the base on one side. On poplar at the junc- 

 tion of the stem and the leaf. Common. 



86. Hickory Louse Gall {Phylloxera carycecauUs Fitch). — Globular or 

 hickory-nut shape. Hollow inside and filled with lice. When fully grown 

 it bursts open and becomes cup-shaped. Green and leathery. On twigs and 

 leaf-stalks of hickory. May and June. Very common. 



ACARINA. (Mites.) 



Family Acarid^. 



The members of this order are minute insects closely allied 

 to the spiders. They are parasitic upon animals, man and 

 plants ; a certain number produce galls. 



87. Wild Cherry Pouch Gall {Acarus scrotina: Beuten.).— Stem-like, ex- 

 panding at the end into a pouch-like sack. About | in. long. Hollow, with an 

 exit on tmder side of leaf. Green or red. In numbers on leaf of wild cherry 

 {Prunus serotina). Common. 



