Feder Korn - aphis oder so genannten "Bug" (Toxoptera graminum Rond.). ugh Erhebung der tatsächlichen Feldbedingungen. Die grüne Wanze atthis (Mai 15) hatte reichlich in Hafer werden so weit nördlich, asManhattan Kans.; aber wo Es wurden Zahlen von Para-Seiten auch schon im Beweis. In der Tat, Herr Phillips gefunden thisto True at Kearney, Xebr., die er besuchte über ein weeklater werden. In keinem Fall wurde ein Feld beobachtet, entweder in der Nähe oder ofManhattan, in der nächsten Woche oder zehn Daj ^s, überall in Kan-SAS, wo der Parasit nicht anwesend war, wo die Grünen bug* aufgetreten. ICir. 93

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Spring grain-aphis or so-called "green bug" (Toxoptera graminum Rond.) . ugh survey of actual field conditions. The green bug atthis time (May 15) had become abundant in oats as far north asManhattan, Kans.; but wherever present there were numbers of para-sites also already in evidence. Indeed, Mr. Phillips found thisto be true at Kearney, Xebr., which point he visited about a weeklater. In no instance was a field observed, either in the vicinity ofManhattan or, during the next week or ten daj^s, anywhere in Kan-sas, where the parasite was not present wherever the green bug *occurred. ICir. 93] 12 A further experiment, this time tried for the purpose of testing thepossibility of hastening the work of the parasite during favorableweather by large introductions, was carried out as follows: The sub-jects of the experiment were two fields of oats, each containing 4acres. In one of these it was determined to introduce enormousnumbers of parasites artificially, keeping records of this field forcomparison with the other field in Avhich no introductions were made.. Fig. 7.—Stalk of wheat, the leaves covered with dead green bugs killed by the parasiteLi/siphlebus tritici. About natural size. (Original.) thus determining the measure of benefit, if any, which resulted fromthe artificial introduction. Mr. Ainslie was instructed b}^ wire to shipfrom Vellington, Kans., 6 bushels of the wheat plants that had beendestroyed by the * green bug and which, in some cases, Avere literallycovered with the parasitized bodies of the pest, upward of 500 havingbeen found on a single plant. (See fig. 7.) Before taking up the ex- fCir. 9.]] 13 periment, however, it was desinihlc (o know just what the conditionswere under which it was beoun. As stated above, one of these oatfields was used for the experiment of introducing parasites, while theother was kept as a check. The fields were so widely separated thatthe introductions could not have spread from one field to the other.Six areas of a sq

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