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a correspondent to tell me in what township he lives, and in what part 
of this township, I can get his location almost exactly. This map is 
exceedingly convenient in following out the spread or distribution of 
any species, as wherever it is discovered by either myself or my assist- 
ant, or wherever it is reported by our correspondents, we indicate the 
exact locality on our map by a small disk of colored paper, using differ- 
ent colored disks for different species of insects. In this way we can 
not only indicate in a very clear manner the spread of the species 
over the State year after year, but we can also indicate the extent of 
more or less local outbreaks, as for instance, in studying the distribu- 
tion of the seventeen-year eieadn in 1897, we used a small disk made 
from canceled 2-cent postage stamps, and wherever the cicada were 
observed or reported in a locality, we marked that locality by one of 
these disks fastened to the map by a small tack. At the end of the 
season we have the entire distribution, so far as we are able to obtain 
it, directly before us, and have but to sketch this area on a base map, 
by the use of oblique lines, to get a drawing ready for the engraver. 
Again, as illustrating the second use, that of indicating local outbreaks, 
of course, there is the first report to go on. This will be indicated on 
our map by a single colored disk. If there is much destruction, and the 
outbreak extends over any considerable territory, we shall very soon 
hear from a greater or less number of people within this area of 
destruction, and by indicating the location of these on our mounted map, 
we will, within a few days, be able to see at a glance just where the 
trouble is being experienced. In other words, we have the storm center, 
as a meteorologist would express it, indicated clearly upon our map. 
This takes but very little time, and I have found it a very great help, 
either in keeping track of the spread of insects that are known to be 
moving in some particular direction, or in showing the area covered by 
the outbreak of any pest. Whileitrequires a little time to attach these 
colored disks, I think that this is more than saved when I come to pre- 
pare a drawing for the engraver, showing the area over which any 
species has extended or become seriously destructive. I do not know 
whether this scheme of mapping outbreaks and diffusions could be ear- 
ried out on a larger scale on the United States map, but it seems to me 
that it could be used in such cases also, though perhaps in a more 
general way. 
In the foregoing I have atvemmptcd to show the manner in hae we 
are trying to carry on our work at the experiment station. Ido not 
present any of these schemes as models, as we understand better than 
anyone else can that there are still many defects and much to be 
desired; but I have presented these matters with the hope and expec- 
tation that they will be of material assistance to other workers, and 
that they will be not only used but improved upon. 
