INSECTS AFFECTING FOREST TREES. 



481 



stout fleshy spine tipped with a dark chitinous point. A pair of simihir spines 

 are found on the last segment and smaller, scattering ones on the dorsal surface 

 of tlie abdomen. Three segments project beyond the tips of the wing pads. 



The grub is a stout, brown-headed, white larva about .'g of an inch long. The 

 tips of the mouth parts and adjacent sutures are dark brown or black. The 

 most prominent characteristic of this grub is the group of seven dark, chitinous 

 spines on the horny anal phite. They are arranged as follows : An anterior 

 transverse row of three, two wider apart behind and between these two others, 

 one in front of the other, figure 2. 



Life History. The life history of this insect has been studied 

 closely by Dr. A. D. Hopkins, who states that the hibernating 

 adults commence to fi)- in the latitude of West Virginia as 

 early as April 20th, and that all have emerged by the loth of 

 May. The species rarely breeds in the bark of logs, but pre- 

 fers to attack living tissues. The primary or entrance gallery 

 is usually extended longitudinally both above and below the 

 main entrance and seldom laterally, though the secondary or 

 drainage galleries may do so. The female deposits from 20 to 

 30 eggs in a mass along the sides of the main or secondary gal- 

 lery, and when the grubs emerge they proceed to feed in a body ~^v4yi 

 on the bark before them. Plate S, figure 4, illustrates a gallery fig. 3. pupa of den- 



,- ^, . . , , 1 -^ 11 1 u 1 DROCTONUS TERE- 



ot this species and shows how its walls have been preserved br-ins 

 b}' pitch. The first egg-depositing period, according to Dr. original. 



Iliipkins, extends through the month of May, and larvae are found from the first of 

 June to the beginning of winter. Pupae commence to appear early in Jul}-, and may 

 be found from then till winter. The beetles of the first brood develop about the 

 middle of Jul)-, emerge in August and possibly late in Jul)-, and young larvae may be 

 again found by August loth. Later in the fall all stages may be met with in the 

 bark of infested trees, some occurring" as low as 6 inches below the surface of the 

 ground. Our own observations agree with those of Dr. Hopkins as recorded above. 

 Natural Eiictiiics. Dr. Hopkins has observed T/ianasiiiiiis diiliiiis ¥dh\-. attacking 

 and killing this large bark beetle and records finding numbers of the insects in the 

 stomachs of brook trout. 

 31 



