860 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



its burrow the eggs laid nearest the entrance have hatched, and the larval galleries 

 will be from 3 to 4™™ in length at the entrance beiore the last eggs are deposited. 



In general appearance the galleries of unispinosus resemble most nearly those of 

 the European Sc. intricatus. 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- 

 stance 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. amygdali. Feeds on Amygdalus. 



Sc. ratzeburgi. Feeds on Betula. 



-Sc. carpini. Feeds on Carpinus. 



Sc. pruni and rugulosus. Feeds on Pyrus, Prunus, 



Crat£Bgus. 

 Sc. intricatus. 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. qtiadrispinosua : Carya. 

 Sc.fagi : Celtis, Fagus (?). 

 Sc. muticus : Celtis. 



Sc. rugulosus : Prunus, Pyrus. (Imported from Eu- 

 rope.) 

 Sc. unispinosus : Abies douglasai. 

 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 (Ehynch, 

 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 

 unispinosus. — After J. B. 

 Smith. 



believe was a beech." 

 really infests the beech. 



Dr. Hamilton states (Can. Ent. xvii, 1885, p. 48) 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 diiferent from rugulosus, and apparently undescribed. 



