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such species as in his judgment would prove beneficial in this country 
as natural enemies of Seolytus rugulosus. Polygraphus rufipennis. Den- 
droeton us terebrans, and Dendrocton us frontalis. Among the thirty-one 
species of pinned specimens received from him on November 12. he 
mentioned Clerus formiearius as being •• beyond a doubt the best de- 
stroyer of Scolytids.*' 
On May 30. 1892, 1 again wrote to Mr. Eickhoff. mentioning the damage 
to oiiTfore$x>by DendroetonusfrontaAis.&nd^XaXedxlizx I was very anxious 
to try the experiment of introducing Clerus formiearius into our forests 
as an enemy of this and other bark beetles. In his reply of June 26 
he referred me to Director C. Schautuss, of the museum at Meissen, 
Saxony, as one who could give me efficient aid in this matter. Upon 
further investigations of the ravages of the bark beetles in our forests 
I prepared a special report, dated July 9. which was addressed to the 
principal owners of the spruce and white pine timber in West Virginia. 
In the closing paragraph of this report, reference was made to the 
successful introduction of the Tedalia into California, and the possi- 
bility of introducing in a like manner insects from Europe which 
woidd feed upon the Destructive Bark-beetle. It was suggested that 
it might be necessary to make a special trip to France and Germany 
for this purpose, and that if the timber interests of the State would 
share in the expenses of such a venture, this object might be speedily 
accomplished. In reply to this communication six of the principal tim- 
ber companies of the State responded with liberal contributions, and 
I was authorized to proceed at once to Emxnpe for the purpose of 
studying the insect enemies of European Scolytids, and to collect and 
import to this country such species as in my judgment would prove 
efficient in checking the ravages of insects in our forests. 
In studying the enemies of European Scolytids, I found, as in this 
country, numerous Hymenopterous and Coleopterous parasitic andpre- 
daceous species in company with the Scolytids in the bark of the infested 
trees, but realizing to the fullest extent the danger of introducing 
insects into this country which might prove injurious as well as beneficial, 
I took every precaution in the selection of the species. Out of quite a 
number of enemies of Scolytids observed and considered, only one. 
Clerus formiearius. was selected, primarily on account of its being 
regarded as the greatest destroyer of European bark beetles; second- 
arily on account of the general opinion of entomologists and forest 
officials whom I consulted, and my own convictions from a personal 
study of its habits, that it would not be injurious. 
The first examples of this European bark-beetle destroyer collected 
by me were taken in the Hagenau forests of Fin us sylvestris, on August 
29, in the first injured tree examined, and they were afterwards found 
common in the larva, pupa, and imago stages in their pupa cases or 
winter quarters in the outer bark of large and small trees which had 
been injured or broken by storm and heavy snow. The bark of these 
