Vill 
over the world each year by the depredations of these and other Hemiptera 
must be colossal. 
“One cause of this devastation is the extraordinary rapidity of in- 
crease, which were it not for restraining parasites and predators, would in a 
year or two leave not a single green leaf on the earth”'). It has been 
estimated that in North America, one fourth to one half of all the grass growing 
annually is destroyed by leaf-hoppers?). Among the Aphidae, at the ex- 
piration of 300 days, the progeny of one individual (supposing each one 
to produce only twenty) would amount to the inconceivable number of 
17,000,000,000,000,000,000,000,000,000,000 *). 
As some offset to this, a few Hemiptera are beneficial, while a few 
provide wax or dyes, or even food for game- or cage-birds, but the total 
value of these is insignificant. 
The Hemiptera are exopterygote, homomorphous, paurometabolous, oli- 
gonephbrous and menorhynchous — that is to say, they develope the organs 
of fight outside the body*), the young undergo only a limited metamor- 
phosis and have no resting-stage °), the Malpighian tubes are few in number, 
and there is a sucking-mouth, which is of the same general form through 
all the instars °). It is thus evident that the Hemiptera are not now closely 
related to any other Order, being the most isolated of all the pterygote 
Orders, though they are doubtless sprung from a palaeozoic or archaeozoic 
Neuropteroid source. 
The Hemiptera of Linneus were practically those of today, except that 
Thrips is now excluded. The Rhyngota, or Rhynchota, are co-extensive with 
the Hemiptera, and the former names should be dropped‘). The Mallophaga 
appear to have nothing to do with the Hemiptera, but the Anoplura are 
doubtful. Since many entomologists would search for records of the latter 
in a Catalogue of Hemiptera, and as they are few in number, I propose to 
include them, as an appendix to a later volume. 
The Hemiptera are divided very naturally into two, doubtless primi- 
tively differentiated, suborders, viz: Heteroptera and Homoptera. It is of 
the former, that the enumeration is commenced, in this volume. 
* * 
* 
It is now nearly sixteen years since the appearance of the first of 
Lethierry and Severin’s three volumes of a “Catalogue général des Hémi- 
ptéres’ “). In the mean time a large number of new genera and species 
1) Kirkaldy 1906 Bull. Haw. Planters’ Sta. I. 271. 
2) H. Osborn. 1893 Rep. Iowa St. Agr. Soc. for 1892, p. 686. [I have not seen 
the original publication, only a separate entitled “Papers on Iowa Insects”, p. 54.] 
3) Buckton. 1876. Mon. Brit. Aphid. I. 80—81. 
4) A few highly specialized forms are apterous. 
5) Some Sternorhynchous Homoptera are holometabolous Heteromorphs. 
6) Except in the males of Coccidae. 
7) The reason some authors have accepted Rhynchota rather than Hemiptera, 
is, perhaps, that they have referred to the 12t edition, instead of the 10, of the 
“Systema Naturae”. In the 10th edition, the Hemiptera are not confused with 
the Orthoptera, and there is therefore no possible reason for the rejection of the 
Linnean name. 
7) These volumes (1893—96) dealt with all the Heteroptera, except the Nepi- 
dae, Miridae and Notonectoideae. 
