INSECTS AFFECTING PARK AND WOODLAND TREES 42 1 



middle of June in Massachusetts, to the early part of July in northern 

 Maine, the larvae feeding on the leaves late in June and in July and early 

 August. The young ^are nearly full grown by the last of July or first week 

 in Augfust, according to the latitude. Still a few occur on trees in Massa- 

 chusetts, as late as the last week of August or early September. 



Dr Packard states that it is very doubtful if there are two broods. He 



observed at Brunswick Me., that all the eggs had hatched by June 23 or 



28. They are placed in two rows, alternately, not exactly parallel, one 



being placed a little in advance of the other, and are inserted at the base 



of the fresh young partly developed leaves of the new shoots, which 



are usually at this time only about 1 or iyi inches in length. The 



presence of the eggs causes a deformation of the shoots, which curl over, 



the incisions being in all cases observed on the inner side of the shoot. 



Dr Packard has described the operations of egg laying as follows : 



The sawing the slit in which the eggs are placed requires about 

 5 minutes. The two sets of serrated blades of the ovipositor were thrust 

 obliquely into the shoot by a sawing movement, the lower set of blades 

 being the most active, and sliding in and out alternately. After the 

 incision is sufficiently deep, the egg is expelled through the inner blades of 

 the ovipositor. 



Dr Packard states that though the slit is at first closed, as soon as the 

 embryo increases in size the twigs swell where they have been cut and the 

 slit enlarges and gaps more or less, and thus affords ready egress for the 

 newly hatched larva, which rarely eats the terminal shoots, but crawls on 

 the leaves of the whorls next thereto. It first nibbles one side of the 

 needle or leaf, leaving it half eaten and rough, serrate, and partly 

 withered along the edge. The presence of the injured leaves is of 

 great aid in detecting the young sawfly larvae, which collect on the 

 verticils of the larches after they have shed their first skin and almost 

 invariably begin to eat the needles one after another. In this way one 

 verticil after another is devoured and when the larvae are half grown, they 

 occasionally collect around the main stem of the twig in singular clusters, 

 with the hinder part of the body curled over the back. Owing to the 

 oblique position in reference one to another, they look much like a ball 



