132 HEMIPTERA. 



legs. Lateral motion is reduced, in this way, to a 

 minimum, as such motion would be of Httle service 

 to a sucking insect. The thoracic region is devel- 

 oped at the expense of the abdominal. The pro- 

 thorax (Fig. 78, ^') overlaps the forward part of the 

 mesothorax, but is not consolidated with it. The 

 huge mesothorax (<^") bears the large, active fore- 

 wings, and contains the great mass of muscles that 

 moves these organs. The posterior edge of this ring 

 is stiffened by chitinous bars. The letter W, conspic- 

 uous on the mesothorax, was formerly supposed to 

 stand for the word War, and the appearance of the 

 insect was dreaded by superstitious people. These 

 peculiar markings are now thought to be due, very 

 largely, to internal causes.^ The metathorax (^"') is 

 reduced to a narrow ring, dorsally, and it bears the 

 small hind wings. The connection of the abdomen 

 with the thorax is broad. 



The note of the male harvest-fly is produced by 

 means of the apparatus on the lower side of the 

 base of the abdomen. If the membranous folds that 

 extend backward over the first abdominal ring are 

 lifted, two cavities are exposed, bounded on their 

 posterior side by brilliant, iridescent plates. Strong 

 internal muscles connect with this apparatus, and by 

 their contraction and relaxation the sound is pro- 

 duced. In the female this apparatus is not devel- 

 oped, and she is, consequently, voiceless. 



The antennae (Fig. 78, at) are bristle-like. The 



1 See " On the Color and Pattern of Insects," Hagen, Proc. 

 Anier. Acad., Vol. XVII., p. 234, April, 1882. 



