PLANT BUGS, APHIDES, AND SCALE. 237 



the Colorado Beetle was, and perhaps still is, called 

 the Potato Bug; and others which are in reality 

 beetles are degraded into bugs. This would be of 

 very little importance to those who know and recog- 

 nize the value of the scientific names ; but it serves 

 to illustrate the fact that the use of popular names 

 alone will be found of but little service to those who 

 desire to step over the threshold which separates 

 popular knowledge (or popular ignorance) from 

 practical knowledge. 



The common Froth-fly (Tettigonia spumaria) may 

 be seen in spring in small patches of white, frothy 

 matter on the young shoots of herbaceous plants. 

 This froth is termed Cuckoo Spittle by country 

 people, from its being conspicuous about the time 

 when the cuckoo arrives in this country. On 

 removing the froth, one or two small green larvae 

 will be found concealed in the midst, which are able 

 to skip away when disturbed. About the middle of 

 June they become pupae. When the perfect insect 

 escapes, it leaves amongst the froth a transparent, 

 horny case attached to the stem by its feet. For- 

 merly they were called Cicadas, but they are not 

 true Cicadas. The perfect insect is of a dirty 

 yellowish-white, thickly clothed with short hairs. 

 The head is triangular and broad, with an eye on 

 each side at the base, and two small ones on the 

 crown. The face has a black stripe down the centre, 

 with several horizontal lines, radiating on each side 

 like a comb. The wing-covers are brown, more or 

 less mottled with olive, with four large whitish 

 patches on the margin ; the wings are transparent 



