146 STARLIGHT AND SUNSHINE. 
the family Zauracee, upon which it conceals itself in the neatly 
folded leaf, as pictured. And yet I see that some collectors have 
found it also on the prickly-ash, hop-tree (Péelea), and syringa. 
Concerning the last mentioned, I can offer no explanation, but 
the other two exceptions—both in the Rue family—have a some- 
what interesting significance, taken in connection with the insect 
next considered. The Azlanxtus silk - worm—introduced into this 
country from China about twenty years ago, and now very com- 
mon in certain sections—for years was not known to swerve in 
its allegiance to its own companion, “tree of heaven.” On the 
basis of the facts already set forth, would any one doubt that if 
its favorite food plant were suddenly exterminated there would be 
a winged stampede, as it were, to the prickly-ash and hop-tree 
(Ptelea), the only two native allies to the Azlantus? But what 
are the singular facts? The moth, I am told by careful observ- 
ers, has quite recently proven fickle to its original diet, and yet 
ignores the kindred plants. As a naturalized foreigner, under new 
conditions, it has concluded to “do as the Romans do,” and out 
of compliment takes the ad of zts closest insect ally, our Pro- 
metheus moth, whose favorite selections are the sassafras and its 
relative the spice-wood, upon both of which the Azlanxtus is now 
occasionally found. There certainly would seem to be some oc- 
cult affinity between these two orders of plants, Lauracee and 
Rutacee, which the botanists have not discovered. 
The exceptions, however, only emphasize by contrast the infi- 
nite number of almost infallible instances, enforcing the irresisti- 
ble deduction of an original universal law of botanical distinction 
among the insect tribes. These lapses, if not instances of mere 
temporary aberration eventually to be discountenanced by the 
“survival of the fittest,’ may perhaps be significantly associated 
with these remarkable freaks of transition noted by collectors— 
those strange dissimilar double broods of the same insect in which 
some scientists discover the pioneers of newly created species.* 
*In the “Semicolon,” for instance, which I have shown to lapse occasionally 
in its botany, and the Alope butterfly and many others, the two succeeding broods 
