INTRODUCTION, 
Though all four of the insects considered in this Bulletin have been 
studied in years gone by and have been treated of in various publica- 
tions, yet some facts of interest are recorded here for the first time. 
The article o1 the Elm Leaf-beetle is reproduced from Bulletin No. 6, 
which has been for some time out of print. Those on the Bag-worm 
and on the Tussock-moth are condensed from our First Report as State 
Entomologist of Missouri, published in 1868, and from later writings, 
and that on the Fall Web-worm is made up from the Third Report of 
that series for 1870, but contains much that is new and especially ap- 
plicable to the District of Columbia, the quoted portions being taken 
in advance from our forthcoming report to the Department. The Bul- 
letin concludes with some facts and suggestions which are also of local 
interest and have been elicited by the exceptional concern shewn by 
the people of Washington in the caterpillar nuisance. Some portions 
of this part of the Bulletin have been given for publication to the 
Washington Hvening Star. 
In treating of the means of preventing the injury and of preserving 
the foliage of our trees we have gone into details as to the most impor- 
tant means in considering the first species, or the Elm Leaf-beetle, so as 
to avoid repetition, and later, in connection with the fourth species or 
Fall Web-worm, referred briefly to other methods. 
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