February, '17] GROSSMAN: COLONIZING PARASITES 181 



envelopes, one cubic centimeter to an envelope, sealed and put in a cool 

 place until colonizing begins. 



During the fall, Schedius are liberated as adults in colonies of about 

 3,500. If the infestation warrants, the colonies are placed along all 

 the roads in a town, 200 to 300 feet from the roadside and about two 

 miles apart. The Schedius are merely shaken from the tube, a tree 

 nearby is marked with a letter "S" and banded with white paint, and 

 a tree on the roadside painted with a letter "S" and an arrow pointing 

 toward the colony. A map is then drawn showing the exact location 

 of the colony and this map is filed with the colony note. 



During the spring, Anastatus are liberated as larvae within the host 

 eggs, in colonies of approximately 1,000. As this species spreads at a 

 much slower rate than Schedius, the colonies are placed in infested 

 woodlands every quarter of a mile on each side of the road, about 

 one hundred feet from the roadside. A small tin can which has three 

 exit holes in the side is stocked with a colony and nailed to a tree. 

 Each can has a cover which prevents the rain from getting in and also 

 protects the eggs from birds. The exact location of the colony is 

 marked on a blue print map of the town and two colonies in each town 

 are marked in the field as are the Schedius colonies, except that an "A" 

 is used instead of an "S." 



In the fall of 1916, over 2,500,000 Schedius, all of which were bred 

 at the laboratory were liberated in fifty-nine towns in New England. 

 The previous spring over one hundred New England towns were col-, 

 onized with Anastatus, using over 12,000,000 parasites. To obtain 

 the latter material, five bushels of gipsy moth eggs were collected 

 from over 1,200 acres of woodland. In order to colonize such an enor- 

 mous amount of material during a period of six to eight weeks, it was 

 necessary to use every available man. Several states cooperated with 

 us in this colonization and without their aid and the use of motor 

 vehicles, it would have been impossible to complete the work. 



In order to determine the success of colonizations, collections of 100 

 gipsy moth egg clusters are made around the center of many representa- 

 tive colonies. After arrival at the laboratory, they are placed in eight- 

 inch glass tubes, numbered, and a record is made of the number of 

 parasites that issue. The collections show that a good per cent of the 

 colonies are successful. 



To determine the dispersion and increase of Schedius, four lines are 

 run to the cardinal points of the compass, using as the center, the exact 

 location where a colony has been liberated. Collections of ten egg clus- 

 ters each are made at the center and at points, every 220 yards along 

 these lines. For Anastatus, eight lines are run and the egg collections 

 are made from the center and every 100 feet for 600 feet, then every 



