Immigration of Animals and Plants. 89 
Longhorn tribe (Clytus pictus) destroyed, about 25 years ago, all the locust 
trees in town; after business was done he was seldom seen. The late State 
Entomologist, Mr. Walsh, of Rock Island, said in the Practical Entomologist, 
Vol. I, No. 4: About a hundred years ago this insect was well known to Forster 
to inhabit the locust in the State of New York. Twenty years ago, although 
the best Illinois botanists agree that the locust grows wild in the southern part 
of Illinois, it was still unknown in that State. Shortly afterwards it commenced 
attacking the locusts in the neighborhood of Chicago, and thence spread grad- 
ually in a south, southwest and west direction through the State, sweeping the 
locusts before it wherever it came. In 1860 it had pretty well destroyed all 
these trees in Central Illinois. This locust-borer Walsh claimed to be distinct 
from the Clytus pictus, and he names it Clytus Robiniz. The legs and horns 
of the latter be stouter in the male and the body tapering behind, but the fe- 
males be undistinguishable in both the species. The larva of the one inhabits 
the locust, the other the hickory. If Waish is right, then, indeed, there is a 
true migration; but our entomologists do not agree with Walsh, and take the 
two borers for identic; then we have only an example of a periodical increase 
in number. Many insects feed on different plants, and a change of appetite is 
not unimaginable. The potato beetle, for instance, after tasting the potato 
plant preferred that to his original food plant, the Solanum rostratum. 
The potato beetle (Doryphora decem-lineata of Say) is quite similar to Dory- 
phora juncta of Germar.' Both. species some entomologists took for identie, 
and as the latter was known in Illinois before the ravages of the other, the mi- 
gratory character of the species was doubted. The differences are so little 
that they can be perceived only by a very close inspection. In D. juncta the 
edges of the black stripes are punctured in a single straight line, and the sec- 
ond and third stripes, counted from the outside, are united behind; when in 
D. decem-lineata the punctures are irregular, and the third and fourth stripes 
are united. Of what value the latter difference is show the exceptions; 
in single individuals the second, third and fourth stripes are united, and in 
others only on one wing-case the junction takes place. Say, himself, suspected 
that the two are only one variable species, but now the entomologists agree on 
the diversity of both. So we have to be contented with the asserted fact, that 
before the year 1864 only the Doryphora juncta, and not D. decemlineata, was 
known in Illinois, and that the latter, since 1861, traveled from Colorado and 
Nebraska eastward. But this example illustrates how species are made, by 
nature or by scientists. There is a variable species, different climate and dii- 
ferent nourishment facilitate differences to become hereditary, and hair-split- 
ting naturalists take the advantage of the slightest diversity to store our books 
with new names. 
The Clytus, as well as the Doryphora, are American species; they migrate, 
but did not immigrate. 
There is a number of injurious insects, of foreign origin, that immigrated in 
North America. There is no doubt that two species of cockroaches, Blatta 
orientalis and Germanica, the bed-bugs, the carpet beetle, and four little 
beetles that infest botanical and zodlogical collections — Dermestes lardarius, 
Anthrenus muszeorum, Ptinus fur and Anobium paniceum — came from the 
eastern continent. These four beetles were probably introduced with stuffed 
animals, with collections of insects and dried plants, the carpet beetle (Atta- 
genus pellio) with woolen fabric. The bed-bug (Acanthia lectularia), which 
immigrated at an unknown time, may be of East Indian origin, but already 
the Greek and Roman authors mention it. In the 11th century it appeared in 
Germany; in the beginning of the 16th century it was known in England, and 
probably the first settlers brought it to this continent. There are two immi- 
grated cockroaches — Periplaneta orientalis, originally from Western Asia, and 
the smaller Blatta germanica, from Europe. The latter is not so frequent as 
the former, and does infest mostly the bakeries. There is a third one (Peri- 
planeta Americana) that spread from South America, and was imported by 
ships into the seaports of Europe. 
