22 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE. 
the cans may be hung on trees, fences, walls of houses, etc. The ants 
prefer to climb for their food, and it is well to hang the cans near ant 
trails going up trees, walls, etc. It is advisable to hang the cans in 
the shade to prevent the evaporation of the sirup, for though it has 
been proved that evaporation does not affect this sirup to a marked 
extent, it is well to avoid raising the.solid contents of the liquid. 
Eight to ten of these cans should be sufficient to place around an 
ordinary city house and lot. If the grounds are large and if as, 
trees are present, more cans should be placed out. 
From the results so far obtained, the careful preparation of the 
poisoned sirup can not be too highly emphasized. Very accurate 
balances are necessary for the weighing out of the poison and the 
tartaric acid. ‘This is especially true when small quantities of the 
sirup are prepared. 
PLANS FOR MUNICIPAL CONTROL WORK. 
In effecting control in towns and cities it is first necessary to ascer- 
tain the extent of the infestation. This should be mapped out so that 
workmen in distributing the cans will be able to refer to the map to 
insure the covering of the entire territory. Cans may be obtained at 
wholesale at about $16 per thousand. About 10 pounds of “ grass” 
sponges will be required per 1,000 cans. These will cost about 75 
cents per pound. Thesponges should be thoroughly washed and dried 
before use. When wet they may easily be torn into pieces about 
2 by 2 inches. Using 1 gill of sirup per can, 200 pounds of granu- 
lated sugar will be required per 1,000 cans. The cost of the sodium 
arsenite is about 80 cents per pound, and 1 pound will be sufficient 
for 1,500 cans. Tartaric acid (crystallized) costs about 70 cents a 
pound, which will be enough for 4,500 cans. From 60 to 100 cans 
will be required per block, depending on the size of the block. The 
late fall, winter, and spring are the most desirable times in which to 
do this work, as in these seasons the natural food is least plentiful 
and the ants most hungry. Two men should be able to prepare the 
sirup, wash and tear up the sponges, and charge about 2,000 cans per 
day and distribute about 1,000 cans per day. 
TRAPPING ANTS. 
By taking advantage of their winter colonizing habit the ants may 
be attracted in large numbers to specially prepared trap boxes, which 
may be fumigated when large numbers have gathered in these boxes 
for winter nesting. Newell and Barber, who originated this method 
of control, describe in Bureau of Entomology Bulletin 122 some very 
interesting and successful trap-box experiments. The boxes were 
filled with decaying vegetation, the heat generated making them very 
attractive as hibernating quarters. Carbon bisulphid was found to 
