102 
of those affecting tobacco, and in the future it will be well for our 
co-workers living within the tobacco-producing area to be on their 
guard. 
Mr. Marlatt spoke of the excellent illustrations given by these papers 
of sudden damage by native insects. The absence of parasites or other 
enemies of the pea louse was remarkable, but might perhaps be attrib- 
uted to the severity of the winter of 1898-99, 
Mr. Felt, in referring to the damage by the tobacco-stalk worm, 
inquired whether this injury was noticeable on fields that had not been 
in grass for some time. His experience had led him to believe that 
Crambids did not fly far, and if this was correct tobacco on old land 
should escape attack, at least in the center of the field. 
Mr. Johnson stated that the field under his observation suffering the 
greatest harm had been in timothy and clover the preceding year and 
was uniformly damaged. Some years ago Mr. Beckwith had reported 
similar injury to tobacco in Delaware, while Mr. Howard had found the 
Same species attacking corn in Maryland. 
Mr. Osborn’s observations agreed with Mr. Felt’s in regard to the 
egg layingof Crambide. They are essentially grass-eating insects, and 
to properly understand their attacks on other crops one must trace out 
their habits in the surrounding fields. In a case coming under his 
observation a field plowed late in the spring suffered damage while 
similar fields plowed early escaped. 
Mr. Felt thought that the eggs of Crambids were dropped at random 
as the females flew over the fields; hence damage by these insects fol- 
lows the flight of the moths. As arule Crambids hibernate as larve. 
Mr. Osborn had found eggs of Crambids abundant on floors of rooms 
where the night previous the moths had been attracted by a light. 
The following paper was then read: 
AN IMPROVEMENT IN THE MANUFACTURE OF ARSENATE OF 
LEAD. 
By A. H. KIRKLAND, Walden, Mass. 
In a paper read before this Association at its meeting in August, 
1897, the writer referred to a method of producing arsenate of lead by 
using nitrate of lead as a source of soluble lead. According to our 
chemist, Mr. F. J. Smith, arsenate of lead formed by this process is the 
diplumbic, or more exactly, a mixture of about one part triplumbic and 
two parts diplumbic, and not the triplumbic entirely, as is produced 
where arsenate of soda is neutralized with acetate of lead, asin the 
ordinary process of manufacture. Arsenate of lead made from the ni- 
trate contains a slightly increased percentage of arsenic (about 5 per 
cent), and as the nitrate of lead may be purchased at a less cost than 
, 
