94 Psyche [August 



The burrows made by the larvte at first extend at right angles to 

 the egg-gallery but soon become quite tortuous. They are rather 

 extraordinary for their length frequently being from 25 to 30 cm. 

 long and toward the last having a diameter of 4.5 to 5 mm. Before 

 pupating, the full grown larvse constructs a pupation chamber, 

 which is often a more definite structure than is commonly made by 

 scolytids. Ordinarily, pupation of those small beetles occurs in a 

 simple cavity hollowed out of the bark or the wood. But in many 

 cases Hylurgops builds a more elaborate structure somewhat sim- 

 ilar to the hibernaculum of Rhagium lineatum and like this, con- 

 sisting not only of an excavation in both bark and sapwood, but in 

 addition surrounded by a wall made up of bits of wood, bark and 

 excrement held together by a substance which acts as a glue (Plate 

 IV, Fig. 4) . The resemblance to the pupation chamber of Rhagium 

 is still further heightened by the presence of a short passage-way 

 made by the larva nearly through the outer bark. These pupal 

 chambers are about 5x8 mm. in diameter. In several cases the 

 larvse had bored into the sapwood and made their pupal chambers 

 entirely in the wood, sometimes penetrating the wood to a depth 

 of nearly 5 mm. The entrance was plugged before pupation occurs 

 and exit was had through a separate hole. Both of these sorts of 

 pupation cavities should probably be considered as adaptations 

 which serve to protect the tender pupse from the larger larvae and 

 the young adults, which appear to have a very voracious appetite, 

 and which extend their tunnels back and forth through the inner 

 bark, often passing over and destroying egg-galleries and larval 

 burrows alike. 



Several full grown larvse were taken from their pupation cham- 

 ber and placed in Stender dishes in slightly moistened sawdust 

 where they were kept under observation during all of the changes 

 which ensued until they became fully colored adults. Briefly, the 

 observations made are summarized below. The time required for 

 the transforming of the larva to the pupa is about four and one-half 

 hours. During most of this time the larva squirmed and wriggled 

 and contorted its body nearly continuously with brief rests after 

 each more violent effort. The effect here was, doubtless, the 

 loosening up of the larval skin, and after about three hours of such 

 efforts the skin appeared to be quite loose and something of the 

 pupal form could be seen beneath it. Finally the larval skin split 



