6 BULLETIN 805, U. S. DEPARTMENT OF AGRICULTURE. 



to the hind margin of the first abdominal segment. Spines darker and more prominent. 

 Average length of 16 specimens 1.85 mm. 



Fourth instar. — Head and thorax yellowish green; abdomen yellow in color. Eyes 

 pearl white. Wing pads extend to hind margin of second abdominal segment. Spines 

 prominent. Average length of 16 specimens 2.1 mm. 



Fifth instar. — Head and thorax pale green; abdomen yellow. Eyes dull white. 

 "Wing pads extend to or nearly to the hind margin of the fomth abdominal seg- 

 ment. First two antennal segments green, remainder dusky. Body broader than in 

 previous stage. Average length of 16 specimens 2.6 mm. 



Adult. 



PI. Ill, G, H. 



General color of adult pale green; face with a white median longitudinal ILae in 

 older specimens but composed of a series of white spots in newly hatched individuals; 

 median line extending from a point midway between the ocelli to a point half the 

 distance to lower margin of clypeus; two short white diagonal bands on each side of 

 median line, the lower one the smaller; a short white Hne, often merely two spots, beyond 

 the diagonal and just above the antenna; a faint white line midway between the ocellus 

 and eye; antennae 1 mm. in length, arising near the lower frontal border of the eyes; 

 clypeus one-third longer than broad; lorse narrow, not reaching the tips of clypeus, con- 

 cave below eyes; gense almost as long and half as broad as clypeus, with one or two 

 faint white spots. Vertex dark green with a median white line, narrowest in middle, 

 its length equal to distance between the oceUi; a white band on each side, dorso-lateral 

 and diagonal to median line. Two ocelli present, marked by two white spots and 

 situated on frontal margin of vertex, their distance apart equal to twice that from the 

 eye to the ocellus; eyes dull white, reddish brown after death. Pronotiun pale green, 

 hind margin very pale, with eight white spots along the frontal margin, the last spot 

 at each end small and often fused with the one next to it so as to form only six spots; 

 mesonotum with two parallel wliite longitudinal lines centrally located and con- 

 nected by a traverse one in the form of a letter H , a faint white diagonal Une present 

 on each lateral margin; scutellum small with a large white triangular area in the center 

 and a small spot on each side along the frontal margin. Abdominal segments yellow- 

 ish green with transverse yellow stripes on their hind margins, anal segment dark green. 

 Wings semitransparent, pale yellowish green. Legs green, tarsi dusky at the tips. 

 Sexual appendages cUiated in both sexes. Average length of 16 specimens 3.12 mm. 



ALLIED SPECIES. 



Three other species of Empoasca were found associated with 

 E. mali on the foliage of nursery apple trees at West Chester, Pa. 

 These species were determined by the late Otto Heidemann, of the 

 Bureau of Entomology, as follows: E. hirdii Goding, E. Jlavescens 

 (Fabricius), and E. unicolor GUlette. Birdii emd jlavescens are very 

 closely allied species, this former being considered by Gillette to be 

 merely a color variety of the latter; these two species resemble 

 mali quite closely and they may be easUy mistaken for it. Unicolor, 

 on the other hand, differs markedly from any of the above three and 

 is readily distinguished from them. 



Birdii differs from Tnali by its smaller size and paler color, by 

 the presence of smoky markings on the elytra, and by the three white 

 spots on the pronotum. 



No attempt was made to study the life history and habits of 

 hirdii but they are probably much the same as those of mali. From 



