Chapter V. 



INSECTS INJURIOUS TO THE DIFFERENT SPECIES OF MAPLE. 



{Acer saccharinum and Acer rubrtim.) 



The number of species here recorded as infesting the different spe- 

 cies of maple, especially the rock or sugar and the red or swamp maple, 

 is upwards of one hundred. Of these only a few are really injurious. 

 Of European insects preying on species of Acer, Kaltenbach enumerates 

 sixty-eight species. The maple-borer, Olycohius speciosus, is the most 

 deadly foe of these beautiful shade trees, and when once established on 

 a street lined with maples, or in a grove, is difficult to eradicate. No 

 caterpillar strips the leaves as a regular recurrent pest, but they are in 

 the Central States often ruined by the cottony maple scale ; otherwise 

 these trees are remarkably free from insect pests, and from their clean- 

 ness and rapidity of growth, as well as dense foliage and beautiful out- 

 lines, will always prove a favorite shade and ornamental tree. 



1. The sugar-maple borer. 

 Glycobius speciosus (Say). 



Boring into the solid trunks of healthy sugar-maple trees, often killing them, a 

 rather large, footless, cylindrical, whitish grub, changing in July to a large, beauti- 

 ful, yellow-striped beetle, marked with a golden W ou the wing-covers. 



Although the question as to whether longicorn larvae will bore into 

 healthy solid wood is by some regarded as undecided, there is no doubt 

 but that the present larva bores for several inches into the trunks of 

 healthy trees, both young maples as well as trees ten or twenty inches 

 in diameter. The following case fell under our own observation. On 

 the grounds of Bowdoin College, Brunswick, Me., for two successive 

 years (1873-'74) a number of fine sugar or rock maples, nearly a foot in 

 diameter, and which had been set out for thirty or forty years, suddenly 

 died, and on being cut up into fire- wood were found to be deeply per- 

 forated in all directions by larvae referable to this species by its large 

 size and resemblance to the locust-borer. More than one larva and one 

 borer were found in the same tree. There seemed little reason to doubt 

 but that the grubs were the cause of the sudden death of the tree. 



In the summer of 1881 I noticed that one tree in the college campus 

 was partly killed by these borers, and that other trees in different 

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