860 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
its burrow the egg! laid nearest the entrance have hatched, and the larval galleries 
will be from 3 to 4""" in length at the entrance before the last eggs are deposited. 
In general appear&noe the galleriee of unixpinosus resemble most nearly those of 
the European Sc. iiitricafu*. But the most interesting point in Mr. Ricksecker's 
communication is the food-tree. No other species of Scolytus whose food-habits are 
recorded lives on conifers. All attack deciduous trees. So striking a departure 
from the general habits of the genus is rather remarkable, and furnishes another in- 
B of the dangers of reasoning from analogy. 
Mr. E. A. Schwarz has furnished me with a list of food plants of the European 
and American species, which is as follows : 
Sc. amyydali. Feeds on Amygdalus. 
Sc. ratzeburgi. Feeds on Betula. 
Sc. oarpini. Feeds on Carpinus. 
Sc. pruni and rugulosus. Feeds on Pyrus, Prunus, 
. Crataegus.. 
Sc. intricatii8. Feeds on Quercus. 
Sc. geoffroyi, pygmceus, kirschi, multistriatus. Feeds 
on Ulmus. 
The American species, of which the food habits are known, 
are the following : 
Sc. quadrispinosus : Carya. 
Sc.fagi: Celtis, Fagus (?). 
Sc. muticus : Celtis. 
Sc. rugulo8U8 : Prunus, Pyrus. (Imported from Eu- 
rope.) 
Sc. uni8pino8U8 : Abies douglassi. 
Of the remaining five species Sc. californicus is tolerably 
common in collections, but the others appear to be exceed- 
ingly rare ; in fact, it is questionable whether any but the 
typical specimens are known. The second food plant of Sc. 
fagi (Fagus) is somewhat in doubt. Dr. Le Conte (Rhynch, 
p. 372) says: "Depredates on beech trees, according to Mr. 
Walsh;" but, on referring to Mr. Walsh's original article 
(Pract. Ent. II, p. 58), we find the following statement: ** I 
obtained many specimens in South Illinois, from what I 
Thus it still remains somewhat doubtful whether the species 
Fig. 293. Mine of Scolytus 
unispinosue.— After J. B. 
Smith. 
believe was a beech, 
really infests th'e beech. 
Dr. Hamilton states (Can. Ent. xvn, 18^5, p. 46) that Scolytus rugulosus breeds in 
hickory twigs, but Mr. Schwarz (Proc. Ent. Soc, Washington, I, No. 1, p. 30) main- 
tains that this hickory species is different from rugulosus, and apparently undescribed. 
