365 
AN ATTEMPT TO CONTROL INSECT PESTS BY THE 
INTRODUCTION OF PARASITES. 
The Importation into the United States of the Parasites of the Gipsy Moth 
and the Brown-tail Moth—a Report of Progress. By Wa. O. Howard and 
W. F. Fiske. Bureau of Entomology, U. S. Department of Agriculture, 
Bulletin no. 91, pp. 1-312, July 29, 1911. 
In the introduction to this volumimous report the senior author states that 
no work of this magnitude has been hitherto attempted and discusses similar 
work elsewhere. Success in parasite introduction, apart from work against 
fixed scale insects, has been limited to the parasites of the sugar-cane leaf- 
hopper in Hawaii, “some reported work” in introducing South American fruit- 
fly parasites to Australia, and the transfer to California of one parasite of codlin 
moth from Spain. ‘It seemed to the writer that by attempting to reproduce in 
New England as nearly as possible the entire natural environment of the gipsy 
moth and the brown-tail moth in their native homes, similar conditions of 
comparative scarcity could surely be reached; and this view he still holds with 
enthusiasm.” (LO. Howard). That is to say, an endeavour was to be made 
te reduce these two moths, which now occur in the United States in enormous 
numbers, to the condition of comparative rarity which they exhibit in Europe, 
by reproducing as nearly as possible their natural environment, so far as their 
insect enemies are concerned. 
The initial idea was to send to America large quantities of caterpillars, and to 
rear from them parasites, which would then be let loose in localities where the 
pests abounded and would breed there. It was hoped by this means to establish 
in America the parasites that check these species elsewhere. This method, which 
seems a simple one, was decided upon partly because the moths themselves were 
introduced and established so casually, and it was thought it would be quite easy 
to introduce their checks. Gipsy moth was brought to Massachusetts in 1868 or 
1869 and escaped by accident. For 10 years it attracted little notice, then it 
increased, and in 1889 it became a serious pest. From that date until 1900, 
up to a million dollars a year was spent in fighting it; then the operations were 
suspended for five years, and in consequence the pest spread from an area of 
359 square miles over 2,224 square miles. In 1905 the present effort was 
commenced by the Federal Department. 
Brown-tail moth was introduced in the early °90’s and has spread rapidly as 
the females fly readily. 
The author goes into considerable and unnecessary detail over his travelling in 
Europe and the arrangements made to start the work. One of the things learnt 
after a few years was that it was not a simple matter to establish parasites ; a 
small colony simply put out ina locality disappeared in many cases, due apparently 
to dispersal so rapidly that they did not find mates. It was found that it was 
