POPLAR BORERS. 439 
7. The poplar goat-moth. 
Cossu8 centerensis Liutner.* 
Plate 1, tigs. 1-12. 
Order Lepidoptera; family Cossidje. 
Perforating the trunks of Populus tremuloides, a worm similar to, bat smaller than, 
the oak caterpillar (X robiniw), the moth issuing from the trees during June. (Bailey.) 
Iii connection with the following account by Dr. Bailey we may say 
that Mr. Fletcher reports that he has found about Ottawa, this moth 
common on the balm of Gilead {Populus balsamifera). The pupa is 
usually extruded from the bark about 4 o'clock in the afternoon, when 
he has frequently seen them. (Can. Ent., xv, p. 203.) 
Cossus centerensis (Plate I) was discovered by Dr. Theodore P. Bailey in 1877. For 
many years previous I had observed that many trees of Populus tremuloides had per- 
ished from some cause then unknown. The central shoots of other trees of the 
same species were dead, and it would only require a few years to finish their destruc- 
tion. Perforations were found in the trunks of these trees, some of recent date and 
some overgrown with bark, leaving the cicatrices plainly visible. 
In July, 1876, a brittle pupa-case of the Cossus was found projecting from one of 
the openings, which gave the first clue to the nature of the borer and destroyer of 
the timber. 
On the 10th of June, 1877, a fresh pupa-case was discovered, and on the 14th of the 
same month the first Cossus was captured, resting upon the same tree trunk. Every 
season since this capture the Cossus has been taken, but in some years in greater 
numbers than others. 
The Cossus usually comes forth between the setting and rising of the sun, and when 
the trees are visited daily the protruding pupa-cases left behind by the escaped im- 
agines informs the collector how many of the insects he may expect to find. 
Their color simulates so closely the color of the bark of the trees that it requires 
good eves and very close observation to find the moths. One unaccustomed to collect 
them might view an infested tree for a long time and not fiud a Cossus, when several 
would be discovered by an expert. An uneven protuberance on the bark, or the 
short stump left of a decayed broken limb are favorite resting places for the insect. 
The moth at first is rather sluggish, aud can be easily captured. After it has been 
abroad for some days it is wild and more or less mutilated. This Cossus is uot 
attracted by sugar, as might be expected from its aborted tongue. The moth seems 
to belong to the genus Cossus Fabr., and not to be congeneric with Xystus robinice. The 
head is short, eyes naked, labial palpi small, appressed, scaled. The thorax is thickly 
scaled, the scales gathered into a ridge behind, and is squarer in front than in Xystus, 
not so elongate or so elevated dorsally. The male antennae are bipectinate ; the 
lamellae rather short and ciliate. The female antennae are serrated. It is allied to 
the European Cossus terebra F., but is a larger insect. It differs from C. querciperda 
Fitch by the absence of any yellow on the male hind wing, and by its darker color 
and closer reticulations. 
In color this species is black and gray. The edges of the thorax and collar are 
shaded with gray, more noticeable on some specimens than others. The primaries 
are covered with black reticulations, which are not always identical in their minor 
details in different specimens, nor sometimes on both wings in the same specimen. 
* The following account of this fine moth was published by the late Dr. James S. 
Bailey, of Albany, N. Y., in Bulletin No. 3 of the Entomological Division of the U. 
S. Department of Agriculture. 
