INJURIOUS INSECTS OF I909 AND IQIO. 107 
of trees in various parts of Minneapolis were found to be seriously 
infested. In some instances of infestation there were suggestions 
of injury by gas (bark peeled off around lower portions of trunks), 
Figs. 53, 54, 55. _The Elm Borer, 8. Tridentata, larva, pupa, imago. Original. 
and in the 1908 instance referred to there had been two leaks in a 
gas-main near the injured trees, and our assistant thought that the 
trees may have been injured by gas primarily, and that the borers 
came as a result of the gas injury. We have reared this same borer, 
S. tridentata, from Poplars. 
Flat-headed Borers, all Buprestids—which may possibly prove, 
when reared, to be more than one genus—were extremely injurious 
to maples in 1910, and bid fair to become established as a promi- 
nent and destructive enemy of these valuable shade trees. Not 
having yet reared these larvae, we are not sure either of the genus 
or species, and hence, cannot speak with certainty of their life- 
history. It is probable, however, that they issue as adults in spring 
and summer. Such being the case, and from what observations we 
have been able to make to date, we would advise the cutting down 
in fall or winter or very early spring, of all trees which are evi- 
