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Colonization in Connecticut .— Cooperative work with the Connecticut Agri- 
cultural Experiment Station at New Haven continued as in the past. A total 
of 25 colonies were released in 1939* thus bringing the final number of colonies 
of 0?. vernalis to 49. The 1939 releasements were made in the following counties: 
Fairfield, 12; New Haven, 8; Hartford, 4; and New London, 1. 
Colonization in New Jersey ,— Heavy beetle infestations still prevail in sec- 
tions of northern New Jersey. It is planned to colonize these as time and 
material permit. Ten colonies were released in this area in 1939# which brings 
the total colonies in New Jersey to 299* The 1939 releasements of JT. vernali s 
were made in the following counties: Hunterdon, J; Somerset, 2; and Morris, 1, 
Colonization in Pennsylvania . —The western spread of the beetle in 
Pennsylvania has advanced rapidly in the last few years, but it has been 
impossible to keep pace with this and meet all requests for parasite colonies. 
In 1939, however, the heavily infested Chester County received 10 colonies, 
which brings the total of this species to 427 Pennsylvania, 
Colonization in Delawar e.— Although the northern part of Delaware is 
heavily infested, the habitats are not ideal for _T. vernalis ; however, 10 
colonies were liberated in the State with the hope of bettering parasite distri- 
bution in that area and to supplement the adjacent heavily colonized areas in 
Maryland. Delaware has now a total of 52 colonies of JT. vernalis . The 1939 
liberations were made with 6 colonies in New Castle County and 4 in Kent County. 
The accompanying map shows in general the total distribution of the 1,272 
colonies of J?. vernalis . 1 
Parasitization of beetle larvae by Tiphia vernalis . — Surveys were conducted 
during the springs of 1935* 193^* and 1939 to determine the effectiveness of 
JT. vernalis as a parasite of the grubs of the Japanese beetle. A pasture at 
Eushland, Pa., was selected for this purpose and in each survey 2 percent of 
a designated 10, 000- square-foot area was dug to determine the status of the 
species. : This entailed the digging of 200 holes 1 foot square over the entire 
plot, each hole being dug to a depth of 6 inches and its entire content noted. 
The following table gives the chief finding for the periods observed. 
Year of survey 
Total grub 
population 
Average grubs 
per 
square foot 
Unparasitized 
grubs 
Parasitized 
grubs 
Number 
Percent 
Number 
Percent 
Number 
Percent 
Number 
Percent 
1935 
1936 
1,146 
816 
1,054 
— 
5*73 
4.90 
5.27 
^ 
444 
liOQ 
38.74 
52.57 
51.99 
702 
388 
506 
61.25 
47-55 
48.00 
1939 
: 548 
: 
