INSECTS, 
121 
Note.—In 1864 chinch-bugs caused a loss in wheat-and corn of 
$100,000,000 ; and in 1850 their ravages in Illinois alone amounted to 
$4,000,000, 
ee 
Fic. 147.—Different stages of the chinch-bug. 
a, egg; 6, newly-hatched 
larva ; c, larva after first moult; @, larva after second moult; e, pupa; 
J, perfect insect. 
Water-Measure Insects (Aydrometride).—These 
are narrow, boat-shaped insects, having long legs with 
which they dart over ponds and 
streams. The Halobates (Fig. 148) 
is found on the ocean, hundreds of 
miles from land, with its eggs. 
Water-Boatman (Woronectide), 
—tThese aquatic insects dart about 
upon their backs with great rapidity, 
using their hind-legs, that are edged 
with strong cilia, and blade-like, as 
oars. They fly, swim, and dive with 
equal ease. The eggs are attached 
to aquatic plants. 
Harvest-Flies (Cicadide).— 
The seventeen-year Cicada (Fig. 149) 
is wedge-shaped, with a broad head 
Fic. 148.—Halobates, an 
insect that goes to sea. 
and prominent eyes. The shrill sound is made by a drum- 
like organ at the base of the abdomen. The eggs, num- 
