46 N. S. ENTOMOLOGICAL SOCIETY. 



In Nova Scotia it was first recognized as a serious pest in the winter of 1915-16, 

 one-third of the stored Baldwins from an orchard in Meadowvale having been found in- 

 fested with hibernating larvae. This discovery, showing how serious a pest this insect 

 could be, pointed out the advisability of making a study of the sawfly both in the field 

 and laboratory and this paper is a report on the work done. 



LIFE HISTORY AND HABITS. 



The winter is passed by the insect in the larval stage, hibernating either in the 

 fruit of the apple, in soft rotten wood, or on the thick bark of old trees. From observa- 

 tions it was noticed that where young orchards are attacked practically 100 per cent of 

 the larvae hibernate in the fruit, while in old orchards only about 25 per cent pass the 

 winter in this manner, the remaining 75 per cent hibernating in soft, dead, punky wood , 

 in old bark or in crevices and crotches. Rotten wood makes the most popular hiber- 

 nating quarters. 



In badly infested orchards as many as five larvae have been counted in one apple. 

 The entrance hole is 2.25 mm. in width and is immediately surrounded by a dark ring of 

 decayed tissue which in turn is encircled by a dark green watpr-soaked area. Inside the 

 entrance hole the larva excavates a tunnel-like cavity in which it passes the winter. 

 This cell is dark brown in color, owing to the lining of decayed flesh, and usually much 

 larger than the body of the larva, although like it, linear in general outline. The en- 

 trance to the cavity is stopped up with "gnawings," supposedly cut away from the flesh 

 of the apple when the cell was in course of construction. In all cases the larva rests with 

 its head towards the exit hole. 



When hibernating in rotten wood the size and shape of the hibernaculum is very 

 similar to the one found in the apple. The larvae burrow out a cell in the punky wood 

 where they pass the winter, always with their heads towards the opening, in anticipa- 

 tion of their exit as adults in the spring. 



About the middle of May the larvae commence to pupate, and in 1916 it took al- 

 most a month for all to trasform, the first pupa formed was on May 13th and the last 

 on the 7th of June. The first adult emerged on May 31st, the last on June 15th. Long- 

 est pupal period 30 days, shortest pupal period 6 days. When pupating the larvae gra- 

 dually contract until they are only about half their original size, the color of the skin 

 changing at the same time from green to brown. This skin is then moulted and the pu- 

 pa is revealed, naked, pale green in color and of the same length as the larva was be- 

 fore the metamorphosis took place. 



From May 31st until June 15th adults were seen emerging, the period covering a 

 little over a fortnight. 



The first eggs were laid on June the tenth. A week later the larvae emerged and 

 commenced feeding on the under surface of the dock leaves, some on the broad leaf, 

 but the majority on the curled leaf dock. Feeding continues through June, and on July 

 4th the larvae commence to pupate in the hollow stems of the dock. Leaving the leaves 

 upon which they have been feeding they wander up and down the stem until they find a 

 place suited to their needs and there bore circular holes, slightly larger than their bodies, 

 into the soft pith. At the same time, on the stems of badly infested plants will be seen 

 many shallow round holes bored about half way through the woody part of the stem. 

 These holes have been made by the larvae in their attempts to pupate and bear evi- 

 dence to the fact that they have the habit of boring several holes before finally selecting 

 one and closing it up. The larvae exhibit the same tendency when seeking hibernating 

 quarters in the apple, partially boring several holes into the fruit before completing the 

 one in which they pass the winter. When they have eaten their way through the tough 

 outer covering of the stem they commence to enlarge the hole and in so doing form a 



