OP WASHINGTON. 



63 



both often occurring in the same I^iriodendron shoot, and their 

 galleries are entirely undistinguishable. The galleries were 

 in various stages of perfection, and in 

 each only a single female beetle was found 

 at work. The accompanying figure (kindly 

 drawn for me by Dr. Geo. Marx) illus 

 trates a complete, or nearly complete, 

 gallery, from which a female specimen of 

 X, tachygraphus was taken, and hardly 

 needs any further explanation. It con 

 sists of a horizontal gallery nearly en 

 circling the core of the shoot, and of 

 one, or two, or more, vertical galleries of 

 considerable length. The walls of the 

 galleries are coated with a black, granular 

 substance, apparently consisting of excre 

 ments permeated with exuding sap, and 

 this is again covered in places with a 

 whitish, glistening substance the "am 

 brosia" of Schmidberger which is sup 

 posed to be the food of the larvae. Only 

 in the vertical galleries eggs or young 

 larvae of the Scolytids were found at this 

 season, their number in each gallery vary 

 ing from two to six, but in many instances 

 they were replaced by another and quite 

 diiferent Coleopterous larva which proved 

 to be that of Bactridium cavicolle. Some 

 times the vertical galleries were crowded 

 with them, and wherever they occurred 

 there was no trace left of the Scolytid 

 eggs or larva. I presume, therefore, that 

 this Bactridium larva devours or crushes 



the eggs or larvae of this Xyleborus ; but it is also possible that 

 they crowd into the galleries before the parent Xyleborus has 

 commenced ovipositing.* 



Xyleborus tachygraphus is one of our rarest Scolytids, and 

 nothing was hitherto known of its food-plants and habits ; but 

 of hardly less interest is the occurrence of X. dispar (pyri 

 Peck) in Liriodendron tulipiferum. In Europe, its native 



* In the hope of obtaining the hitherto unknown male of X. tachy 

 graphus, which is presumably of the same form as that of X. dispar, I 

 carried home several infested shoots cut up in pieces of convenient 

 length, but in the breeding-jars they at once commenced to mould and 

 the Scolytid larvae perished. Some specimens of Bactridium cavicolle 

 were, however, bred. 



Fig. 3.-Work of Xyleborus 

 tachygraphus in Lirio 

 dendron tulipiferum. 

 Upper figure : trans 

 verse section ; lower 

 fi g u r e : longitudinal 

 section. Natural size. 



