31 
era range of these insects to Central America. CTnlike several others 
of our destructive locusts that are Limited to moderately high altitude-.. 
this one is a frequenter of low elevations ranging from near sea level 
to not much over (>,(>()() feet above. This is true with reference to it 
within the Limits of the United States, but in Mexico I have taken ir 
at altitudes of 8,000 feet and upwards. Although it is found over so 
great an extent of territory, it occurs only al certain suitable Localities 
within these boundaries. Its distribution appears to be controlled al- 
together by climatic conditions, the chief of which is the presence of a 
certain amount of humidity. Like bivittatus and differentialis, it is a 
frequenter of low grounds, cultivated fields, shady margins of woods, 
etc., where vegetation is rank and tender. On account of these pecul- 
iarities in connection with its naturally wide distribution, it has become 
our commonest locust in the United States. 
The breeding habits of femur-rubrum are such as to especially aid the 
insect in its life among cultivated fields, and hence it is that it has be- 
come such a general nuisance. Were it not so generally preyed upon 
by a great number of different birds, mammals, reptiles, and predaceous 
insects, as well as by several parasites, it would be a much greater pest 
than it is. 
It can readily be recognized from the following description and illus- 
tration (Fig. 15): 
As compared with spretus the only very marked difference between the females is 
the shorter wings of this species, yet there are other slight differences observable 
when a large number of specimens are compared, The eyes m. femur-rubrum are 
slightly more prominent. The head, pronotum. and sides of the thorax are usually 
some shade of olive brown, varying from pale to almost black. The black line be- 
hind the eyes is quite broad, seldom broken up, and is distinct in the darkest speci- 
mens. The humeral (entering) angles of the posterior margin of the pronotum are 
more rounded and not so sharply defined as in spretus; the median carina is usually 
more distinct on the anterior lobes, while the lateral carina' are rather more obtuse 
and not so well defined : the punctures on the posterior lobe are more distinct. The 
wings extend but slightly beyond the extremity of the abdomen, usually less than 
one-tenth their length. In this species and atlanis the intercalate vein is present in 
the tegmina dimly and imperfectly, it is true, but it can be (dearly distinguished for 
more than half the length of its course. In spretus it is wanting, its place being 
marked by the line of union between the two rows of cells. The fuscous spots or 
dots are not so conspicuous or widely spread over the apical portion of the w ing, and 
the tegmina are narrower and straighter. As a very general rule the external face 
of the posterior femora is black or brown, the 
lower margin and lower half of the inner face 
bright coral red; when these colors are well de- 
lined there is a yellow space or stripe between the 
red and black, but these markings are subject to 
Considerable variation, the red being sometimes 
... .. ., , .. ,', , , FIG. 15. Mtianoplua femur -rubntm— 
entirely wanting, the external face dark, and the natural si,o (after KilevK 
lower margin yellow: sometimes the dark is re- 
placed by pale olive. The tibiae are most generally bright red. but this character 
is not without exceptions. Usually there ie* a pale ray extending from the base of 
the wings to the posterior femora, but is occasionally wanting in dark specimens, 
and is generally absent in spretus. The pros tern al spine is not so distinctly quadrate 
