17 



The galleries are made in the root and lower part of the crown of 

 the plant, just below the level of the soil. In young trees, an inch 

 or more in diameter, the burrow is circular, and kills the plant by 





.... 







Fig. 7.— Galleries of Corthylus punc- 

 tatissimun in huckleberry mut.s — 

 enlarged (original). 





Fig. 6.— Ambrosia of Corthylus puncfatissimus : a, 

 detached dumb-bell shaped pairs of cell— greatly- 

 enlarged (original). 



girdling it. In small shrubs, like huckle- 

 berry, the galleries are spiral, as indicated 

 clia grammatically in fig. 7. Short, straight 

 galleries ascend or descend from the primary burrow, following the 

 grain of the wood. These are occupied by the young, and in them, when 

 full grown, the larva? undergo their transformations. The system some- 

 times includes a second and more rarely a 

 third circular gallery. Prof. A. D. Hopkins 

 states that in sassafras trees of considera- 

 ble size he has sometimes found their gal- 

 leries overgrown by the annual layers and 

 the tree unharmed. 



The food fungus, taken from galleries in 

 roots of huckleberry ( Gaylussacia res'uiosa), 

 is sketched in fig. G. It consists of a con- 

 fused mass of rather large co^iuia»heaped 

 together like fish roe. The cells by mutual 

 pressure lose somewhat their spherical 

 form. Connecting threads arfc sometimes 

 discoverable, and attached to thesv short 

 and thick branches which give rise to two 

 or three spherical conidia. At a in the 

 figure dumbbell shaped pairs of these cells 

 are shown detached from the mass. The 

 stain of the fungus is intensely blue-black, 

 and penetrates the wood deeply. 



Corthylus columhianus Hopkins (fig. 8).— 



- 



Corthylus columbianut 

 larged (origimal). 



tie is somewhat larger than 

 81)67— No. 7 2 



-The Colombian timber bee- 

 the preceding speries. which it otherwise 



