PACKARD.] THE POPULATION OE AN APPLE TREE. 167 



says that about the first of June the female deposits her 

 eggs. The grubs change to chr3^salides early in the spring, 

 and in New York the beetles appear earlj^ in May. 



The Cylindrical Bark Borer, or Tomicics m.aU, produces a 

 disease like fire-blight, causing the bark to shrivel and peel 

 off and killing the branches. Dr. Fitch states that young, 

 thrift}' trees when attacked by this beetle soon after putting 

 forth their leaves in the spring suddenly wither as though 

 scorched by fire, the bark becoming loosened from the wood, 

 and soon after numerous perforations like pin holes appear, 

 revealing the secret of the sudden destruction befalliug the 

 tree. All these bark boring beetles have a common form, 

 that of a C3-linder squarely docked at the end, looking as 

 though they had been made by the inch and then cut up into 

 lengths of about a line each. The body is cov- pjq_ 132. 

 ered over with fine hairs, so that it acts as a 

 brush, like those used for cleaning lamp chim- 

 neys. The end of the body is sometimes scooped 

 out like a gouge, so that the little beetle can 

 shovel out the dirt from its house in a true Mile- 

 sian fashion. The use of the hairs undoubtedly 

 is seen when the insect laj's its eggs. The female '-Toinicus. 

 beetle tunnels a' hole in the bark and makes little notches 

 at intervals, in which it deposits an egg. On her returu, by 

 means of the short stiflT hairs projecting from her bod^-, she 

 brushes the dirt into the little notches, thus covering up and 

 protecting her eggs. Figure 132 represents the Tomicus 

 XTjlofjraphits, enlarged several times. Tills is a timber beetle, 

 and there are several allied forms, but all are much like the 

 apple bark borer. It seems from the observations of JM. 

 Ferris, as quoted by Dr. Fitch, that tlie bark boriug beetles, 

 i.e., those infesting fruit trees, differ from the timber l)cetles 

 in an interesting peculiarity. In the bark beetles there is 

 a division of labor, the males doing most of the work. 

 "There are commonly several males in company with Ijut 



7 



