INSECTS AFFECTING PARK \ND WOODLAND TREES 335 



fusor Kirby. The parent of this latter insect is represented at plate 63$ 

 figure 1, and its operations are familiar to many lumbermen because its 

 coarse white sawdustlike chips may be frequently observed dropping from 

 logs piled in mill yards and its large galleries are not uncommon defects in 

 timber. The sawyer is rarely found attacking living trees. It prefers to 

 breed in those which are dying or nearly dead and therefore is a follower of 

 the above rioted barkborers. Other species have. a similar habit, notably 

 the ribbed rhagium, Rhagiu 111 1 i neat u m Oliv., a species which is fre- 

 quently destructive to the bark of trees previously killed by other insects. 

 Its broad flattened grub delights to revel in moist decaying tissues and 

 its very characteristic cells fpl. 64, fig. 7, 8, 10 1 are walled by long white 

 splinters torn from the wood forming a portion of its oval pupal cell. 

 Another species, Pytho americanus Kirby, is also associated with 

 the preceding in this work of reducing decaying tissues to a still finer 

 condition. It may be easily recognized by its oval cells which instead 

 of being bordered by linear chips torn from the surface of the wood are 

 lined with nearly decayed debris from the bark [see pi. 64, fig. 6, 9]. 



These two species in conjunction with the bark borers soon reduce the 

 inner tissues of an attacked tree to a mass of decayed vegetable matter and 

 render the stripping of the bark an easy matter. Plate 56, figure 2, illus- 

 trates the secrecy of these operations very nicely. Apparently the trunk of 

 the tree has suffered little or no injury, but on removing the bark its inner 

 layers are found to be a mass of corruption, as shown at plate 56, figure 3. 

 The bark loosens and soon drops in large patches, exposing the wood to 

 other enemies such as ambrosia beetles. 



The condition of such a tree which scarcely two years before it was 

 photographed was in full vigor, is well shown at plate 54, figure 1. The 

 small black holes in the bare wood are entrances to galleries of wood borers 

 known as ambrosia beetles and these lead into lateral galleries from which 

 in turn there are series of perpendicular chambers. This latter insect, 

 X ) 1 o t e r 11 s bivittatus Kirby, is common in soft woods and is 



