1919 ENTOMOLOGICAL SOCIETY. 51 



losing hold this fall as anticipated;, it will only be a year or two before they are 

 again an item of greatest importance to the wheat grower. The Bureau of Ento- 

 mology, Division of Cereal and Forage Insects, under the direction of Mr. W. E. 

 Walton, has instituted a series of stations in the principal wheat-growing areas 

 of the United States where detailed studies are being made, in co-operation with 

 the state authorities. Sowing experiments, where wheat is sown on different dates 

 and variously handled, are in progress, in the district covered by the Lafayette 

 Indiana Station, from Michigan to Tennessee. At Centralia, Illinois, in the centre 

 of the southern Illinois wheat belt, we have a substation comprising 18 acres of 

 land in charge of Mr. C. P. Turner and conducted in co-operation with Dr. S. A. 

 Forbes. There intensive studies are made and much stress is laid on the effect of 

 meteorological conditions. For obtaining meteorological data the several instru- 

 ments giving records which may have a bearing on fly activities are utilized; thus 

 we have in continuous operation not only the hygrothermograph, soil thermograph 

 and rain gauge, but also the atmometer, an instrument which measures the com- 

 bined effects of temperature, air currents and humidity, terrestrial radiation 

 thermometers, anemometers, etc. This work has been in progress for two years 

 and many valuable data have already been obtained. 



The principal remedies advocated at the present time are sowing after the 

 fly-free or safe date and destruction of infested stubble and subsequent volunteer 

 wheat. Since one of these important recommendations is sowing after the so-called 

 '• fly-free '' or " safe." date and since this date is necessarily not identical year 

 after year, efforts have been made to determine a simple means whereby the county 

 agricultural agent or a group of farmers can determine for their locality the safe 

 sowing date each year. Thus various types of cages are being used to determine 

 which are giving emergence records similar to natural conditions and checks are 

 obtained by making daily records of Hessian fly caught on tanglefoot covered 

 screens erected in the field and by daily egg counts made on specified plants. 

 Sowing at the proper time is not alone a remedy and at most is not a preventive 

 for spring infestation. To be 100' per cent, effective it must be accompanied by 

 the destruction of wheat stubble wherever possible and the elimination of volun- 

 teer wheat. Our experiments show that plowing wheat stubble to a depth of 6 or 

 8 inches and subsequent harrowing destroys at least 92 per cent, of the flies but 

 the practice of sowing clover in wheat makes it difficult to secure the universal 

 practice of this measure and until the sowing of clover with other crops or by 

 itself becomes more general we must continue to depend largely on sowing at 

 the proper date to escape fly injury. Here again the value of proper sowing is 

 dependent to a large extent on another factor, namely co-operation. If all of the 

 farmers in the community do not follow the practice of sowing after the fly-free 

 date, the one or more farmers disregarding the proper sowing date will furnish 

 breeding grounds for the first brood of flies which may, if weather conditions are 

 favorable, mature and infest the later sown wheat or at least the early sown crops 

 will produce a generous supply of flies to infest the wheat in spring. Our laws 

 do not make it possible for us to specify sowing dates and we must depend on the 

 intelligence and honor of the community and much can be done towards securing 

 the co-operation of a comnnmity by honor conditions. This is aptly illustrated 

 by an occurrence which happened in southern Indiana a year or so ago when 

 we were conducting a campaign in a particiilar locality to secure the co-operation 

 of farmers to hold off sowing wheat until advised. One young man asked to learn 

 the penalty if he promised to hold off sowing, but for some reason or other went 



