THE DOG-DAY HARVEST-FLY. 217 



periods so distant that vegetation often has time to recover 

 from the injmy inflicted by them ; but were they to appear 

 at shorter intervals, our forest and fruit trees would soon be 

 entirely destroyed by them. They are moreover subject to 

 many accidents, and have many enemies, which contribute to 

 diminish their numbers. Their eggs are eaten by birds ; the 

 young, when they first issue from the shell, are preyed upon 

 by ants, which mount the trees to feed upon them, or destro}' 

 them when they are, about to enter the ground. Blackbirds 

 eat them when turned up by the plough in fields, and hogs 

 are excessively fond of them, and, when suffered to go at 

 large in the woods, root them up, and devour immense 

 numbers just before the arrival of the period of their final 

 transformation, when they are lodged immediately under 

 the surface of the soil. It is stated that many perish in the 

 egg state, by the rapid growth of the bark and wood, which 

 closes the perforations and buries the eggs before they have 

 hatched ; and many, without doubt, are killed by their peril- 

 ous descent from the trees. 



There are sevei'al other harvest-flies in the United States, 

 the males of which are musical ; but their drums are con- 

 cealed within little cavities in the sides of the first abdominal 

 ring. One of these is found in Massachusetts, and, though it 

 never appears in such great numbers as the preceding species, 

 it is more common or more generally met with throughout 

 the State. It may be called the dog-day harvest-fly, or 

 Cicada canicularis (Fig. 88), from the circumstance of its in- 

 variably appearing with the beginning of dog-days. Dui'ing 

 many years in succession, with only one or two exceptions, 

 I have heard this insect, on the 25th of July, for the first 

 time in the season, drumming in the trees, on some jxirt of 

 the day between the hours of ten in the morning and two 

 in the afternoon. It is true that all do not muster on the 

 same day ; for at first they are few in number, and scattered 

 at great distances from each other ; new-comers, however, 

 are added from day to day, till, in a short time, almost every 

 28 



