Two New Shade-Tree Pests. 135 



dies. The excrement and cast skins of the larvse are left within the 

 mines. When full grown the larvse burst through the upper epidermis 

 of the leaf or the roof of their home, and fall to the ground into which 

 they work themselves for a short distance, usually about half an inch, 

 sometimes an inch, and there make their thin, brown papery cocoons. 

 In summer they soon transform in these cocoons, probably in a week 

 or two, into the black sawflies. 



Eggs are soon laid and another brood of larvae begin their de- 

 structive work of "blistering" the leaves. I have not been able to de- 

 determine definitely the number of broods of this sawfly which develop 

 during the growing season, as the broods overlap, but there are at least 

 two or three broods, perhaps more. Beginning in May, their work con- 

 tinues throughout the summer until October in this latitude. After about 

 June ist, I have found the insect in all stages on or under the infested 

 trees almost any day until September. This is in striking contrast to the 

 well defined, one-brooded life of its near relative, the elm sawfly, herein 

 discussed. 



The insect hibernates as a larva in the soil near the surface in its 

 brown, papery cocoon, the transformation to the pupa occurring in May. 

 Thin.y-one cocoons were found in an area of only four square inches 

 under a small tree last May. 



Remedial suggestions. — During the past season I have tested a 

 simple, practicable, and effective method for controlling this insect. Find- 

 ing that it hibernates within an inch from the surface of the soil, I buried 

 several cocoons at depths of two, four and six inches. But very few of 

 the flies emerged from any of the buried cocoons. A thin layer of the sod 

 beneath the infested trees was at once removed and should have been car- 

 ried away promptly, but it was delayed until many of the flies emerged. 

 Thus the infestation was not checked so completely as it shovild have 

 been, but the trees are not nearly so badly injured this year as in 1904. 



By promptly removing about one or two inches of the sod or toll from 

 beneath trees infested by the insect about May ist, and carrying it to a con- 

 siderable distance or burying it, this insect can be easily and effectively con- 

 trolled. By thus preventing the emergence of the spring brood of sawflies, 

 the development of succeeding broods is stopped. In many cases, it would 

 doubtless be practicable to simply spade under the sod to a depth of six 

 or eight inches, and pack it down hard. Care should be taken to remove 

 the sod over an area extending a foot or two beyond the circle bound- 

 ing the points to which the longest limbs reach. Thorough and prompt 

 burying of the cocoons in this manner about May ist, will control this 

 sawfly miner and preserve the beauty of this desirable European tree, 



