146 
POPULAR SCIENCE REVIEW. 
bushels per acre. But when we examine the production of 
the individual States, taking some in which the Western potato- 
beetle had made its appearance in force in the above years, and 
others which had either remained uninvaded or been only 
partially attacked at the 
same time, we 
get the following 
average produce per acre 
in bushels : — 
1869. 
1870. 
1872. 
New Hampshire . 
... 150 
88 
94 
New York . . . 
... 114 
98 
88 
Pennsylvania . . 
... 93 
87 
99 
Missouri .... 
... 115 
103 
80 
Illinois .... 
... 103 
81 
75 
Ohio 
. • . 112 
72 
80 
Michigan .... 
... 155 
95 
66 
Minnesota . . . 
... 112 
57 
99 
In general terms, we may say that the falling off is greater 
in those States which the beetle had fully occupied ; but it is 
evident that other causes of fluctuation must be at work to give 
rise to the variation in the amount of produce. Still, although 
the mischief done by the beetle may have been exaggerated, it 
is certain, from all accounts, that it is by no means inconsider- 
able, and the recovery of the crops in some of the States which 
suffered most from the early visitation of the insect is directly 
ascribed by the Grovernment statistician to the vigorous warfare 
which has been waged against it by the farmers. 
The beetle which has inflicted so much damage, and caused 
so much alarm in the United States, that the prospect of its 
succeeding in crossing the Atlantic has raised almost a panic in 
some European countries, is by no means a formidable animal 
to look upon. It is a beetle of the tribe of Phytophaga, or 
plant-eaters, and of the family Chrysomelidse, all the members 
of which are of small or moderate size, of a rounded, ovate, or 
oblong convex form, with the head short and deeply sunk in the 
next segment (prothorax), the antennse generally thread- 
like or beaded, and only of moderate length, and the tarsi 
(feet) with only four apparent joints. The insect, as already 
stated, was described in 1824 by Thomas Say as belonging to 
the genus Doryphora (“ spear-bearer ”), in which the meso- and 
metasterna are produced forward into a spine ; this is the origin 
of the name of the 44 ten-lined spearman ” given to the insect 
by Mr. B. D. Walsh. The genus Doryphora has been consider- 
ably subdivided by recent authors, and by some entomologists 
the species under notice is referred either to the genus Poly- 
gramma of Chevrolat or to Leptinotarsa of St&l, in which the 
sternum is unarmed (fig. 4) ; but it will be sufficient for our 
present purpose to speak of it under the old name of Doryphora 
decem-lineata . 
