98 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



than those of Scolytiis rugulosus^ the maximum length being about 

 2| inches, with an average of S^V inches. 



There are two complete broods each year — the summer brood and 

 the fall brood, the latter being the hibernating one, the beetles ap- 

 pearing in early spring. Beetles of the summer brood appear in 

 maximum numbers during the last half of August, as shown more 

 in detail in the following table : 



Table I. — Enicifjciicc of siDinncr brood of beetles of PJilorotribiis liminarif<. 



■« The first column sliows beetles actually counted and taken from a breeding cage; the 

 second row of figures shows, somewhat estimated, numbers of beetles gathered on screens 

 at windows. All counts made between 4 and G p. m. 



''This table shows August 21 to be the date of maximum emergence of beetles. 



DESCUII'TION. 



Average length, 2.25 mm., iiverage width. 0.75 mm. Body elongate, subcjiiu- 

 drical, strongly punctured and with yellowish bristles arising from the punc- 

 tures; color varying from light brown to almost black. Head globular, nearly 

 vertical in front, anterior part fringed ; eyes narrowly oblong, closely joined to 

 the scape and extending about half their length below it ; mandibles short and 

 broad, distal part curved and strongly acute; mouth parts partly inclosed, gular 

 suture distinct; funiculus of antennfe five-.iointed ; club compi-essed, composed 

 of 3 triangular segments: first joint longer than wide, globular; scape circular, 

 clavate. Thorax almost cylindrical, i-tronglj^ angled at caudal end. First and 

 second coxte widely si>i)arated, globular; femur stout, outer edge serrated; tibia 

 stout, compressed, lower half of outer edge serrated and ending in an apical 

 tooth; tarsus stout, shorter than tibia, third joint bilobed, fourth indislinct. 

 fifth as long as first and second together; tarsal claws simple. Ventral side of 

 abdomen and posterior edge of last segment strongly concave; elytra anteriorly 

 rounded and deeply margined, sides parallel, surface with regular striae which 

 contain circular, regularly placed depressions, elevattnl parts with yellowish 

 bristles arising from faint punctures. 



