BUREAU OF EXTOMOLUUi'. 327 



setts — 11,187 bands being used. Spraying operations were consid- 

 erably interfered with by an unusual amount of rainfall during the 

 month of June. Two horse-drawn spraying machines were converted 

 into motor-propelled outfits so that there Avere available for the sea- 

 son's work 14 motor-truck spraj^ers and 5 horse-drawn machines. 



Considerable difliculty was experienced in securing prompt deliv- 

 ery of arsenate of lead, owing to strikes and freight embargoes, but 

 as the season was later than usual, resulting in delayed pupation of 

 the caterpillars, it was possible to carry on spraying work satis- 

 factorily during the first week in July. This, in part, compensated 

 for the diflicultics encomitered in the early part of the spraying 

 season, although the treatuiont is mosi effective if applied as soon 

 as possible after the caterpillars have hatched. The machines were 

 distributed along the border of the infested area in New Hampshire 

 and Massachusetts and one si)rayer Avas assigned to VNork in Rhode 

 Island. The spraying in Connecticut was done with the e(]uipment of 

 the State entomologist and by the men in his employ. During the 

 season, spraying work was carried on in 22 towns, and 3,617 acres 

 were treated. In addition to this, 14r,954 trees grooving in orchards 

 and pastures or on private grounds were sprayed. 



Experimental work. — The extremely severe winter of 1919 re- 

 sulted in heavy mortality of gipsy-moth egg clusters over a large 

 part of the infested area. Along the seacoast and in the southern 

 part of the area this condition did not exist, except to a moderate 

 degree. Eggs of the gipsy moth that were deposited near the 

 ground, where they were protected by snow, which was unusually 

 heavy during the winter, hatched in a normal manner. Extensive 

 experiments indicate that a temperature of 20° or more below zero is 

 fatal to most of the eggs in the cluster. In case they are protected by 

 snow or other means, this rule does not hold good. 



Egg parasitism by Anastatus hifasciatiis has been very satisfactory 

 in many localities during the past season. The maximum destroyed 

 by this insect, however, is rarely over 50 per cent of the eggs in the 

 clusters, so that the gipsy moth can not be controlled completely by 

 this insect. This parasite spreads very slowly and there are infested 

 areas in the deep woodlands where the species has not yet become 

 established. During the year 1.220,000 specimens were liberated, 

 principally in woodland areas in New Hampshire. 



In the fall of 1919 Schedkis kuvanae^ another egg parasite, was 

 found more abundantly than during tlie previous year. It is par- 

 ticularly susceptible to low temperature during the winter and its 

 numbers were very greatly reduced as a result of the severe winter 

 of 1919. Five hundred and forty thousand were colonized in eastern 

 New Hampshire in the fall of 1919. Colonization of these two 

 species was made possible by assistance rendered by the State ento- 

 mologist of New Hampshire. 



Compsilura concinnata, a tachinid fl}', occurred in about the same 

 degree of abundiince as during the previous year. High parasitism 

 was noted, however, in many of the small isolated colonies, and in 

 one locality under close observation in Melrose the destruction of 

 gipsy-moth caterj)illai-s by this" insect was very much higher than 

 usual. 



