198 PLUM. 



proved most destructive, as also at other gardens in the same 

 village. I have also received it from Shropshire, where it had 

 been equally destructive. I have now had the species under 

 investigation for nearly two years." 



Mr. Newstead kindly lent me his own drawing from life of 

 the maggot and pupa much magnified, which, with his per- 

 mission, I have had copied, and insert at p. 197. 



The specimens sent were very characteristic of the method 

 of attack. The life-history is that the little beetles appear in 

 April or May, and begin to bore into the bark, and the females 

 tunnel their vertical galleries between the inner bark and sap- 

 wood. Here they lay their white eggs singly side by side along 

 this "mother-gallery," and from these eggs the grubs hatch 

 after a few days, and feed on the inner bark by preference, 

 but otherwise in the sap-wood. The maggot-tunnels neces- 

 sarily all start off, as with so many of the bark-beetles, at 

 right angles from the mother-gallery, by the sides of which 

 the eggs were laid; and when full-fed, if there is still a good 

 thickness of bark over them, they turn to chrysalids at the 

 ends of their tunnels ; otherwise, if the bark is too thin a 

 protection from their having eaten it away, or from other 

 causes, they pierce a little way down into the solid wood. 



This was very observable in the small branches sent me. 

 At first, from the short boring down into the wood being 

 stopped at the entrance by the powder (frass), the results of 

 the_ feeding of the grub, the perforation was very likely not 

 noticeable ; but later on, when the beetles had developed and 

 emerged, the minute cylindrical holes down into the wood were 

 as observable as those through the bark, and were sprinkled 

 in such numbers in the Plum branches sent me, that I counted 

 sixty perforations at least in a space of one inch in width by 

 two in length, the short tunnel varying in depth from about 

 the sixteenth to over the eighth of an inch, and often entering 

 the wood in a slightly slanting direction. 



The first round perforations through the bark are made for 

 entrance holes by the beetles; presently, if the brood of beetles 

 comes to maturity each at the end of its larval tunnel, they 

 will pierce their way oat, and the bark will be sprinkled with 

 the round shot-like holes they have made as exit passages. 

 Where there is only a small quantity of attack the character- 

 istic form of the vertical mother-gallery, with maggot-galleries 

 starting at (more or less) right angles from it, is clearly ob- 

 servable ; but where much infestation is present the various 

 galleries may intersect each other, and the larvae instinctively 

 diverge from their straightforward course to avoid the tunnel 

 of an adjacent larval worker, so that the workings are irregu- 

 larly interlaced. 



