6 BULLETIN" 254, U. S. DEPARTMENT OF AGRICULTURE. 



Second-instar nymphs. — Average length 2.5 mm. Head more 

 pointed or acute. Black-line facial markings becoming distinct. 

 Light median dorsal stripe remaining. 



Third-instar nymphs. — Average length 3 mm . Spines on hind 

 legs prominent. More mottled with gray markings. Head larger 

 but not more pointed or acute. Dorsal stripe remains, extending to 

 tip of abdomen. Eyes darker and more prominent. First indication 

 of wing pads. 



Fourth-instar nymphs. — Average length 4.2 mm. Head more 

 pointed. Black-line facial markings very distinct. Dorsal stripe 

 remaining. Spines on legs prominent. Wing pads larger. 



Fifth-instar nymphs. — Average length 5 mm. Body darker green. 

 Eyes slightly lighter green than body color. Hairs on tip of abdomen. 

 Head slightly more pointed. Wing pads well developed and opaque. 



COLOR FORMS OF ADULTS. 



In 1913 Mr. Wildermuth noted many adults of a brown color. 

 Thinking these might be another species specimens were sent to 

 Prof. Osborn for determination, who replied to the effect that "the 

 brown form is a variation of the green form which is usually the 

 most common." The writer observed many of this brown form 

 during January and February, 1914, but was unable to find a single 

 brown individual during the spring and summer months. All adults 

 reared from brown parents were entirely green and remained a true 

 green until death. Because brown-form adults have been found 

 only among the wintering adults the writer is inclined to believe that 

 the brown coloration is due to a fading of the green pigment caused 

 by prolonged life, as is the case with wintering adults, or by extreme 

 weather changes. Recently Prof. Osborn has remarked that his 

 "collection of brown individuals at El Paso, Tex., March 3, 1910, 

 bears out the supposition that these may be old and faded speci- 

 mens." 



LIFE HISTORY AND HABITS. 



As with all jassids, this species has three stages in its life cycle, 

 namely, egg, nymph, and adult. The adult female deposits her eggs 

 in pockets in leaves and stems, and these eggs hatch under Arizona 

 conditions in from 3 to 35 days, depending upon the temperature. 

 Through a series of five molts the nymphs increase in size, develop, 

 and with the last molt transform to the adult. The length of the 

 nymphal stage, as with the egg stage, depends largely upon the tem- 

 perature, averaging 30 days in Arizona. 



NUMBER OF GENERATIONS. 



The number of generations a year will vary in different parts of the 

 country according to the various climates, and is likely to fluctuate 

 from year to year in accordance with seasonal variations. Prof. 



