538 The University Science Bulletin. 



of the first pair of legs. In the second instar the length of the 

 mesothorax and metathorax together is approximately equal to 

 that of the prothorax, while in the first stage the prothorax is longer 

 than the other two together and the mesothorax is slightly longer 

 than the metathorax. 



From the second to fifth instars color variation in the head and 

 thorax can be found. Some specimens in each instar were both 

 collected and reared in which the head and thorax were of the same 

 color as the body. Others had head and thorax both washed in 

 dark reddish brown, while still others had a pale prothorax with a 

 dark mesothorax and metathorax, so that the thorax appeared to be 

 distinctly banded. In the third and fourth instars the bands were 

 of such dark-brown pigment that they appeared as black bands to 

 the naked eye and made the nymphs very conspicuous. Apparently 

 this color variation has no relation to sex, since both sexes have 

 been found to have these different combinations. 



On the fourth, fifth and sixth abdominal segments of the first 

 instar appear two large, oval, orange spots. These spots make the 

 first-instar nymphs more conspicuous and more vividly colored 

 than any of the other instars. They probably indicate the loeation 

 of the spittle glands which secrete part at least of the viscid fluid 

 of the foam. Garman (1921) says that they appear as yellow spots 

 on the side of the abdomen of Philcenus, and Osborne (1916) found 

 them as black spots in another species. Both writers state that the 

 glands are found on the seventh and eighth segments, but in 

 Lepyronia they are found on the above-mentioned segments. On 

 the other hand, Kershaw (1914) says that the fluid is produced by 

 the anterior or smooth portion of the malpighian tubes. The whole 

 question is an interesting matter for further investigation. 



ECONOMIC IMPORTANCE. 



In general froghoppers are not considered economically important, 

 since they are found feeding chiefly on weeds and wild plants. 

 There are a few, however, which have been reported as doing con-' 

 siderable damage to certain cultivated host plants. Osborne (1916) 

 thinks that the damage caused by froghoppers has been over- 

 looked. According to him, Philcenus spiwiarius L. considerably 

 affects clover, for he noticed that the plants which are attacked 

 wither and do not bear heads. He also has observed Philcenus lin- 

 eatus L. being so abundant on grass and hay crops as to occasion 

 distinct losses, timothy and redtop being most frequently injured. 



