December 4, 1891.J 



SCIENCE. 



317 



which seem to have been very considerable. In the Slates 

 •of North Dakota and Minnesota it is probable that at least 

 $400,000 have been saved on account of work done by direct 

 advice of entomologists — work they have in some instances 

 forced upon the farmers. Two hundred thousand dollars is 

 a probable estimate of the amount saved by ploughing the 

 land last autumn. Another equal amount has been saved 

 by the use of " hopperdozers." Professer Bruner tolls me 

 that a sufficient number of grasshoppers have been actually 

 taken this year, which, if left alone and allowed to lay their 

 egffs, might next year have devastated the whole crops of 

 these two States and the adjoining parts of Manitoba. These 

 successful operations have been carried on by the State ento- 

 mologist of Minnesota, Professor Lugger, and by Professor 

 Waldron of North Dakota, ably aided by the advice and 

 assistance of tlie agent of the Department of Agriculture, 

 Professor Bruner, under Professor Riley's instructions; and 

 I think it is no exaggeration to say that at least $400,000 have 

 been actually saved in hard cash on this year's crop, not to 

 speak of the enormous loss which would most probably have 

 followed next year had they been left alone, and had climatic 

 conditions been favorable for their increase. 



The amount of damage done to crops every year is so vast 

 that the flgures excite incredulity from those who do not 

 study crop statistics. The agricultural products of the United 

 States are estimated at about $3,800,000,000. Of this it is 

 thought that about one-tenth is lost by the ravages of insects. 

 This is in many cases unnecessary. In short, a sum of 

 $380,000,600 is given up without a murmur and almost with- 

 out a struggle by the people of the United States. 



Crops of all kinds are injured, and simple remedies are 

 known for many of the attacks, and are more or less adopted. 

 Some have already come into general use. Paris green is 

 now applied to potato fields almost as much as a matter of 

 course, as manure is to fertilize the soil. As an instance 

 of how a saving may be made even in well established 

 methods, I give the following: Through the work of Mr. W. 

 B. Alwood of the Virginia Experiment Station, improved 

 -machinery and the water mixtures of poisons have come into 

 general use among the farmers and potato-growers in the 

 Norfolk region, and some of the largest growers now claim 

 that they at present do for from $40 to $60 what used to cost 

 them from $500 to $600. To-day, in California and Florida, 

 orange trees are universally treated with kerosene and resin 

 emulsions or poisonous gas for scale insects. 



In the treatment of cabbage caterpillars, pyrethrum di- 

 luted wiih four limes its weight of common flour, and then 

 kept tightly closed for twenty-four hours, leaves nothing to 

 be desired, and thousands of dollars are yearly saved to small 

 growers who most need the assistance. 



Many excellent remedies have been devised by a mere 

 modification of existing agricultural methods. Instances of 

 these are found in the early and late sowing or harvesting 

 of some crops, as sowing turnips between the broods of the 

 turnip flea-beetle, the late planting of cabbage for the root- 

 maggot, the late sowing of wheat for the Hessian-fly, etc. 

 In the J879 Report of the United States Department of Agri- 

 culture was first detailed the only successful method of treat- 

 ing the clover-seed midge by cutting or feeding off the first 

 crop before the young larvse are sufficiently matured to leave 

 the heads and go into the ground to pupate. This was sim- 

 ply a change of one week, by which not only is the insect 

 -destroyed, but the clover is saved in better condition than 

 binder the old method. 



During the present summer Professor Osboru has discov- 



ered that a serious pest of the clover plant, Crrapholitha in- 

 terstinctana, a small moth, may be destroyed in all its stages 

 by simply stacking the hay soon after it is cut. 



In the Southern Slates Mr. Howard Evarts Weed writes 

 to me with regard to the cotton worm: " The loss would in- 

 deed be great were it not for the fact that the planters keep 

 it in check by the prompt application of Paris green in a dry 

 form. The only method now used is to apply it by means 

 of two sacks attached to a pole and borne through the plan- 

 tations by a negro mounted on a mule, who rides down the 

 rows of plants. This gives perfect satisfaction, and the far- 

 mers of the Stale tell me that thej' want no better remedy 

 for this insect." 



Mr. F. W. Mally writes on the same subject: " The ben- 

 efit which the public generally derives from the researches of 

 economic entomologists is well illustrated by the result of 

 the cotton- worm investigation published in the fourth report 

 of the United States Entomological Commission. In that 

 report estimates of damage, etc., are given, and I will only 

 allude to the benefit which the planters have derived from 

 the report. Formerly, planters waited until the August 

 brood of the Aletia issued and depredated on their cotton. 

 This brood may be called the migratory one, since it spreads 

 over vast areas of cotton fields. At that time, too, the 

 planters used Paris green just as they purchased it from the 

 dealers. They have now been educated to know that the Aletia 

 propagates in certain quite well defined centres earlier in the 

 season, and that if taken in July (or about five weeks earlier 

 than they had been accustomed to), they can prevent their 

 spreading to larger areas. Now, too, they dilute the Paris 

 green with fiour and finely-sifted wood ashes, greatly reduc- 

 ing the cost of the poison per acre. At the same time the 

 acreage or area to which poison is now applied has been re- 

 duced tenfold, at least. For example, here in the Red River 

 Valley, for 30 miles up and 50 miles down the river in July 

 there were only two plantations (together about 2,000 acres) 

 upon which Aletia was found. In August this brood would 

 have spread over almost the entire section mentioned. Paris 

 green was applied to this limited infested area, and the 

 larger areas saved from injury. The saving is hardly to be 

 estimated. The above appeal's to me to be one of the great- 

 est triumphs of economic entomology, and, I may truthfully 

 say, also of my most estimable chief, Dr. C. V. Riley." 



With regard to another injurious insect, the following 

 facts well illustrate what may be done by following the ad- 

 vice of an experienced entomologist. 



During the year 1885 the Hon. Moses Fowler, a wealthy 

 banker and landowner of Lafayette, Ind , applied to Profes- 

 sor F. M. Webster, an agent of the United States Department 

 of Agriculture, then located at that place, for relief from 

 very serious depredations by an unknown enemy to his corn, 

 which was damaging some of his fields from 5 to 75 per cent, 

 he having this year 10,000 acres of land devoted to this crop. 

 Upon examination the depredator proved to be the well- 

 known corn root worm, the larva of Didbrotica longicornis. 

 Mr. Fowler estimated the loss in his fields by reason of this 

 insect at $10,000, with a probability of still greater injury 

 the following year. On the advice of Mr. Webster, the next 

 season he sowed 5,000 acres of the worst infested lands to 

 oats, and the following year the other 5,000 acres was 

 treated in the same manner, the first 5,000 acres being this 

 year again devoted to corn. As a result of a continuation of 

 this rotation the pest has been pi-actically exterminated, 

 thereby, according to Mr. Fowler's estimate, saving him 

 $10,000 per annum. 



