FAM, MEMBRACID.E 27 



developed, but the others are evident. In the adult the abdomen of the insect is so modified in the 

 separate sexes as to require separate descriptions. 



In general, each segment from the second to the seventh, inclusive, is ring-like in form and 

 consists of a distinct tergum, pleuron and sternum. The first segment consists of a tergum only and 

 this sclerite is only partially developed, the lateral extremities being shortened. The abdominal terga 

 are long, horse-shoe shaped sclerites covering not only the dorsum but most of the lateral areas. 

 They end ia a rather sharp angle at the junction of the pleura. The pleura are short and subrectan- 

 gular, and are located on the ventral rather than the lateral part of the abdomen. The first eight 

 abdominal pleuia bear spiracles in the extreme cephalic mesal angle of the sclerite. The spiracle for 

 the first segment is, indeed, not in the chitinized part of the sclerite at ali, but is located in the mem- 

 brane between this sclerite and the metathorax in such a position that it appears as a part of the latter 

 segment. The spiracle of the second segment, likewise, is usually found at the ver}' edge of the sclerite 

 if not actually in the membrane, The sterna are uniform in the anterior region.of the abdomen but 

 are modified in the posterior region in the two sexes, Each sternum is typically a long curved plate 

 forming the ventral floor of thesegment and connecting the pleura of each side. Usually it is smooth 

 and unsculptured. The abdomen is much thicker at the anterior than at the posterior end, and for 

 that reason the anterior sterna are the longest and widest. 



From an external view of the complete insect very little of the abdomen is visible. The 

 projecting posterior process of the pronotum hides the dorsal surface, while the two pairs of wings 

 folded tightly against the lateral regions conceal these areas. For these reasons the dorsal and lateral 

 parts of the abdomen are not suited for taxonomic study, It is doubtful, however, whether these areas 

 would offer characters of value even if they were plainly visible, The color of the abdomen is usually 

 uniform and agrees with the general color of the remainder of the body. The under-surface is 

 generally darker than the upper, and the segments are in some cases bordered with a lighter shade 

 than that of the ground color. The anterior end of the abdomen is inclined to be of a lighter hue than 

 the posterior, and all the segments are likely to vary in tliis respect within a species. The entire 

 abdomen, and particularly the ventral surface, is much given to pubescence; this is very noticeable in 

 certain forms aloag the pleural sclerites. Occasionally the white tomentose patches are found on the 

 abdomen as on the thorax. When present they are usually on the lateral areas of the first three 

 segments and show through the basal part of the vving. The terga are often punctate, but this 

 condition is seldom seen on any part of the abdomen, and even on the terga the punctures are much 

 less developed than on the head or the thorax, 



The apical segment of the abdomen of theadult can be discussed onl)' in relation to the different 

 sexes, since the modifications in the sclerites caused by the development of the genital organs are 

 quite distinct in the male and the female. 



The Female : In the female the sterna of segments two to five inclusive are comparativel}' 

 uniform, each being a broad, flat, slighty curved plate extending across the abdomen. The sixth 

 sternum is indented at its median posterior margin, and the entire ventral part of the segment is 

 usually much recurved, The sternum of the seventh segment is deeply notched in its median 

 part to enclose the rounded base of the ovipositor. This is the last entire segment in the female 

 abdomen and its shape varies greatly according to the type of ovipositor surrounded. The structure 

 of this sternum has been successfully used as a specific character in many genera, In some cases the 

 sternum is so deeply indented that from an external view it appears as two separate sclerites. The 

 eighth segment may or may not show a sternum, but if one is present it is reduced to a small triangular 

 sclerite on either side of the ovipositor and does not e.Ktend entirely across the abdomen. In most cases 



