180 INSECTS INJURIOUS TO VEGETATION. 



nuisance, and do their work quickly; the latter have a longer 

 time assigned to them, corresponding in some degree to the 

 progress or continuance of vegetation. The facilities afforded 

 for obtaining food influence the duration of life; hence those 

 grubs that live in the solid trunks of perennial trees, which 

 they are obliged to perforate in order to obtain nourishment, 

 are longer lived than those that devour the tender parts of 

 leaves and fruits, which last only for a season, and require no 

 laborious efforts to be prepared for food. The harvest-flies 

 continue only a few weeks after their final transformation, and 

 their only nourishment consists of vegetable juices, which they 

 obtain by piercing the bark and leaves of plants with their 

 beaks; and during this period they lay their eggs, and then 

 perish. They are, however, amply compensated for the short- 

 ness of their life in the winged state by the length of their 

 previous existence, during which they are wingless and grub- 

 like in form, and live under ground, where they obtain their 

 food only by much labor in perforating the soil among the 

 roots of plants, the juices of which they imbibe by suction. 

 To meet the difficulties of their situation and the precarious 

 supply of their food, for which they have to grope in the dark 

 in their subterranean retreats, a remarkable longevity is as- 

 signed to them; and one species has obtained the name of 

 Cicada septendecim, on account of its life being protracted to 

 the period of seventeen years. 



This insect has been observed in the southeastern parts of 

 Massachusetts, and in the valley of the Connecticut river, as 

 far north at least as Hadley; but does not seem to have ex- 

 tended to other parts of the State. The earliest account that 

 we have of it is contained in Morton's " Memorial," wherein 

 it is stated that "there was a numerous company of flies, 

 which were like for bigness unto wasps or bumblebees," which 

 appeared in Plymouth in the spring of 1G33. " They came 

 out of little holes in the ground, and did eat up the green 

 things, and made such a constant yelling noise as made the 

 woods ring of them, and ready to deafen the hearers." Judge 

 Davis, in the Appendix to his edition of Secretary Morton's 

 " Memorial," states that these insects appeared in Plymouth, 



