SOME WOOD-BORING INSECTS 



393 



to remain mostly within their burrows in the wood, 

 have ordinary antennae. 



Felt reports a species, P. ruficornis, as injuring birch 

 and maple floors in some cottages at Saranac Inn, New 

 York. 



WHITE-MARKED SPIDER-BEETLE 



Ptinus fur 



There are two other species of the family Ptinidse be- 

 longing to the genus Ptinus and known as the spider- 

 beetles that demand some 

 notice. There is the white- 

 marked spider-beetle, Ptinus 

 fur, which is perhaps the more 

 common of the two. Both are 

 often found in the storerooms 

 and cellars of houses, especially 

 of those that have been occu- 

 pied a long time. 



The white-marked species is 

 a reddish-brown beetle with its 

 body well covered with choco- 

 late colored hairs (Fig. 135). 

 The two sexes differ markedly 

 from each other. The wing 

 covers of the male are reddish-brown throughout, 

 whereas each wing cover of the female is marked with 

 two patches of white hairs. These patches tend to run 

 together and form two white bands across the back 

 of the beetle. The female, which is considerably larger 

 than the male, attains a length of about one-eighth of 



Fig. 135. — The white-marked 

 spider-beetle, enlarged. 



