182 
of the Black Hills, show no preference whatever for the injured trees over the near Im- 
perfectly healthy ones. This latter result proves beyond all question that healthy 
tncs are attacked ami killed by this hark beetle; that it can not he attracted to trap 
trees; that its broods can be destroyed by felling the infested trees during the fall, 
winter, and spring i iths and removing the hark from the main trunks and leav- 
ing it on the ground to dry; that the wood of such trees can he profitably utilized 
for railroad ties, mine timbers, and cord wood. 
Thus we have found that while some of the methods of work in forest insect inves- 
tigations are complicated and expensive, both in money and time, they have led to 
the discovery of some simple, inexpensive, and practical methods of preventing 
losses. 
The reading of the paper was followed by an appreciative discussion in which J. B. 
Smith, C. M. Weed, and others took part. 
The following two papers by E. P. Felt, of New York, were then read: 
Importance ok Laboratory and Field Work in Economic Entomology. 
The purpose of this paper is not so much to present new facts as to provoke a dis- 
cussion, and in this way draw out valuable points in the experience of different 
workers. It always seemed to the speaker that laboratory work should form the 
basis for field experiments, and that one should always accompany the other. There 
has been more or less talk in recent years about experiments of magnitude; those 
conducted on a commercial scale and the like, and yet, in reality, some of our most 
satisfactory results have been obtained in breeding jars no larger than a jelly tumbler, 
or even a small homeopathic vial. It is very true that the breeding jar, be it large 
or small, does not afford natural conditions, and results are more or less affected la- 
this variation; and yet, an insect confined in such small quarters can be observed 
much more closely and a correspondingly larger amount of knowledge gained con- 
cerning its habits; for example, we have had no trouble in keeping elm-leaf beetle, 
Galerucella luteoh. Mull., for approximately thirty days under such close observation, 
and in spite of the apparently unfavorable conditions they approximated a full quota 
of eggs. Even more remarkable results were obtained with the grapevine root worm 
beetle Fidia viticida Walsh, a specimen of which not only lived in a breeding jar 
for upwards of nine weeks, but deposited the very large number of 1)00 eggs. The 
advantage of these very small jars is that they permit isolation and enable one 
to make much more accurate observation than would be possible in the field. The 
results obtained in the laboratory are carefully checked by others in the field, and in 
our experience ( in some cases at least), it pays well to build larger breeding cages in 
the field and observe conditions there, not only in comparison with the indoor breed- 
ing cages, but also with uninclosed food plants; for example, some exceedingly valu- 
able data were gained the past season inaseriesof eight large cages, which contained 
from one to two full-sized grapevines in the midst of a commercial vineyard. The 
conditions were somewhat abnormal on account of the line win 1 screening, prevent- 
ing, to a slight extent, the normal circulation of air, and the temperature inside of 
the inclosures was consequently a little higher; nevertheless, by means of such cages 
we obtained unquestioned data as to the time the beetles appeared above ground, 
something of great importance, whether the adults are to be destroyed by catch- 
ing or killed by an application of some arsenical poison. These cages also gave 
exceedingly valuable data on the proportion of pupae which could be killed by 
cultivation, and likewise the efficacy of poison in destroying the beetles. Our 
indoor cages, for example, show that where the insects were confined absolutely 
to leaves which had been covered by the poison, they could be killed in nine to 
twelve days or thereabouts, whereas, in our larger outdoor breeding cages, in spite 
of the fact that the spraying was done by hand in a most thorough manner, practi- 
cally none of the insects were dead after a period of twelve days. The results from 
the indoor and outdoor cages differ, and yet there was a relative gradation in those 
obtained between the indoor and outdoor cages and the larger experiments wherean 
acre or more was involved. The point we wish to make in this connection is that 
while no one of these experiments gave conclusive data, the combination of the three 
enabled us to form a very fair judgment of what actually was oceuring, and we 
believe that by these means we have been able to estimate, with considerable 
accuracy, the relative value of various methods of controlling the pest under consid- 
eration. In this connection a word regardingthe reliability of the untrained observer- 
is not out of place. It frequently occurs that the experimenter has not the money 
or the time to make an extended series of experiments, and he is therefore often 
obliged to avail himself of the experience of intelligent parties who follow his advice. 
Occasionally it is possible for him to be present when the spraying, for example, is 
in progress, and to observe the manner in which the work is done, and he may later 
