ENTOMOLOGY. 163 



was called to the fact that where corn had followed cotton crops no damage was 

 apparent but where the preceding crop had been corn, the damage was in 

 many cases very severe, often resulting in a total loss of the crop. 



The night hawk (Chordeiles acutipemiis texensis) and the predaceous mag- 

 gots of the robber fly Erax lateralis are mentioned as natural enemies of this 

 beetle. It appears evident that the beetles winter in the fields where they 

 develop and that crop rotation is effective in preventing serious injury. 



Progress and prospects of tick eradication, C. Curtice {XJ. 8. Dept. Agr., 

 Bur. Anim. Indus. Rpt. 1910, pp. 255-265, fig. 1 ; Circ. 1S7, pp. 255-265, fig. 1).— 

 In this paper the author briefly discusses the beginning of tick eradication, the 

 results of 5-years' work, obstacles to progress, reasons for tick eradication, and 

 prospects for the future. 



In summarizing the eradication work it is stated that at the time of writing 

 " there have been* freed of ticks and released from quarantine 127 counties and 

 l)arts of 20 counties out of 929 originally infected; 90 are in varying degrees 

 of disinfection. Over one-seventh of the counties have been cleaned, and over 

 one-fifth of all the originally infected counties have been worked in. About 

 one-tenth of the counties now infected are being worked in and are partially 

 clean." 



The use of arsenical dips in tick eradication, B. H. Ransom and H. W. 

 Gbaybill iU. ^'. Dept. Agr., Bur. Anim^ Indus. Rpt. 1910, pp. 267-28^, i)ls. 6, 

 fig. 1). — This paper is based upon the investigations previously noted (E. S. R., 

 27, p. 84). 



A new leakage gage, C. W. Woodwobth (California Sta. Circ. 75, pp. 15, 

 figs. 8). — This is the sixth of the author's papers on fumigation studies (E. S. 

 R., 26, p. 561). 



A new method of determining the leakage in fumigation work, through the 

 use of a leakage gage which the author has invented, is here described. This 

 new gage consists of a tent clamp and a set of 3 tubes, 1 of brass ending in 

 a nipple for attaching a rubber mouthpiece, and the other 2 of glass, along 

 1 of which is a scale so graduated as to show the percentage of leakage, and 

 a small glass chamber of water with which the 3 tubes communicate. The 

 graduated tube is closed at the top but has a passage to the clamp ring which 

 allows air to pass through the tent cloth. The other glass tube is open at 

 the top. 



The method of determining leakage is as follows : The glass chamber is filled 

 partly full of water and a double thickness of the tent is clamjied into the clam]) 

 ring, the tester blows gently through the rubber mouthpiece on the brass tube 

 until the water rises to the top of the open glass tube, then the percentage of 

 leakage is read on the scale where the top of the water column reaches in the 

 closed glass tube. 



The theory upon which most methods of measuring leakage is based is that 

 the rates of leakage of gas through different pieces of cloth will show approxi- 

 mately the same difference that is found between the rates of flow of air 

 through these cloths when it is forced through under the same pressure. The 

 method used in this apparatus is to measure the resistance to the passage of 

 air presented by the cloth to be tested as compared with an opening of a known 

 size. The scale is graduated between and 100 per cent leakage by testing in 

 the gage a series of metal disks containing holes of different known area and 

 determining the ratio of their areas to the area of the clamp ring. 



Pressure gages for determining leakage were found to be more practical than 



•volume gages, a test tube gage being the simplest form of pressure gage. A 



suction gage, which was the most satisfactory form used in the laboratory, 



requires a special form of regulating clamp. The use of a tester enables one 



