302 BOARD OF AGRICULTURE. [Pub. Doc. 



Experimental Work. 

 Throughout the season no measures were at any time adopted 

 until they had been determined to be effective by experiments in 

 the laboratory and by practice in the field. During the time 

 employed in destining the eggs a series of experiments was 

 conducted to determine the best method of destroying the cater- 

 pillars. A supply was obtained by artificial hatching. The 

 experimental work was continued during the spring and summer. 

 The experiments with Paris green gave the best results. When it 

 was properly applied to plants, all newly hatched caterpillars 

 which were fed upon them in the laboratory died within a few 

 days. In the field similar results were obtained. In the experi- 

 mental work no injury to the foliage was observed, when a mix- 

 ture consisting of one pound of poison to one hundred and fifty 

 gallons of water was used. Later, glucose was added to retain 

 the poison upon the foliage. 



Spraying with Insecticides. — Paris Green. 

 When it became evident that Paris green was effective, prepara- 

 tions were made for its use on an extended scale. During the 

 first part of May teamsters were employed, and twenty spraying 

 outfits were put upon the road in Medford. It was soon seen that 

 the number of men and teams was insufficient. Ten additional 

 spraying outfits were purchased, and the effectiveness of all was 

 doubled by improved appliances. In May and June seven super- 

 intendents were selected from the force to oversee the work of the 

 men, and to instruct them in the use of the apparatus. One man 

 was given general charge of the teams and implements. Each 

 team and the accompanying squad of men was under the imme- 

 diate charge of an inspector. When the apparatus had all been 

 thoroughly tested, and the men had attained the skill requisite for 

 its intelligent use, the entire force was sent to the periphery of the 

 region then known to be infested, and all were instructed to work 

 toward the centre. The infested area was thus sprayed until 

 the middle of July. At that time numbers of caterpillars were 

 fully grown and had stopped feeding ; some had pupated and 

 others were wandering from tree to tree. Other means were 

 then used to destroy both caterpillars and pupae. 



Police. 

 When, in May, the caterpillars were seen to be spinning down 

 from the trees, an attempt was made to maintain a cordon of 

 police around the territory most densely infested, with a view to 



