384 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



6. The sixteen-legged maple-borer. 



Mgeria acerni (Clemens). 



Order Lepidoptera; family ^geriad^. 



Following the work of the flat-headed horer, burrowing under the bark of the soft 

 maple, sometimes girdling and killing the tree, a caterpillar with sixteen legs, spin- 

 ning a cocoon of silk covered with its castings; the moths issuing from the tree late 

 in May and thence through the summer, the worms occurring under the bark through 

 the summer and winter. (Riley.) 



This borer is sometimes very destructive to soft and sometimes to 

 sugar maples, especially young trees, in Ohio, Illinois, and Missouri, 

 the moths sometimes emerging in great numbers from the trunks of the 

 trees in May and June. Mr. G. R. Pilate states that the red maple trees 

 in Dayton, Ohio, were greatly infested by this borer, in consequence of 

 which a large number of those shade trees are dead or dying. (Bull. 

 Brooklyn Ent. Club, vol. i, 20.) 



Mr. Kellicott remarked in the Canadian Entomologist for January, 

 1881, that the " larvfe of this moth are annually doing much damage 



to the hard maples {Acer saccharinum), 

 planted so generally in this city [Buffalo] 

 for shade ; they are less destructive to the 

 soft maple {A. riibrum). It appears that 

 they seldom attack uninjured trees, but 

 depend upon accidents to afford them op- 

 portunity to enter the inner bark and su- 

 perficial wood ; when once established they 

 keep at the scar or wound year after year, 

 thus preventing recovery and causing the 

 trunks to become rough and unsightly; in 

 many cases the trees are thus almost 

 ruined. The moths appear most numer- 

 ously from May 20 to June 15. I have 

 not been able to find, after patient search, 

 this borer in our forest maples." 



Professor Riley says he has always found 

 the worms in such trees as have been in- 

 jured either by the work ot the flat-headed 

 borer, by the rubbing of the trees against 

 a post or board or in some other way. « Where the bark is kept 

 smooth they never seem to trouble it, the parent evidently preferring 

 to consign her eggs to cracked or roughened parts. For this reason the 

 worm is not found in the smoother branches, but solely in the main 

 trunk." 



Remedies.—'' Whether the soap applications will prevent the moth 

 from depositing her eggs is not known ; judging from analogy, probably 

 not. Yet it will tend to keep the bark smoother, and in being used to 



Fig. 142. — c, ^geria acerni ; a, citer- 

 pillar; h, cocoon; d, pupa cases. — 

 After Riley. 



