372 



LovETT (A. L.)- Insecticide Investigations. — Oregon Agric. Expt. 

 Sta., Corvallis, Bull. 169, April 1920, 55 pp., 2 plates. [Received 

 1st July 1920.] 



This buUetin is a report on the progress of an investigation on 

 insecticides of which some of the earlier work has already been noticed 

 [R.A.E., A, iii, 264, 655, 759 ; v, 477]. The investigations show that 

 acid lead arsenate is more effective than the basic salt, the proportion 

 assimilated by the larvae being greater. One pound of the acid lead 

 arsenate in 400 U.S. gallons of water was effective against very small 

 tent caterpillars [3Ialacosoma], and would probably be equally so 

 against newly hatched codHng moth larvae [Cydia 'pomonella]. The 

 ordinary commercial lead arsenates are nearly pure acid lead arsenate. 

 The powdered form is superior to the paste and keeps better. Sub- 

 stances known as spreaders, which increase the covering power and 

 adhesiveness of the spray, add greatly to its efficiency. The most 

 practical in order of merit are : caseinate, glue, soap bark, and oU 

 emulsion. They are not improved by the addition of phosphates or 

 sulphates. 



The three factors, method of application, the spray solution and the 

 spray material, all affect the efficiency of the spray, and the improve- 

 ment of any one of them decreases the relative importance of defects 

 in the other two. 



In the calyx apphcation for codUng moth a fine misty spray is as 

 effective as a driving spray. But undue importance should not be 

 attached to the calyx spray. In Oregon usually less than half of the 

 infestation is due to calyx entry ; it is the last brood of larvae, which i 

 inferts the fruit n late August and early September, that causes the 

 heavy losses and is hardest to control, owing to the difficulty in 

 timing the spray. 



The calcium arsenates have a high killing efficiency, but are not so 

 stable as the lead salts, and an excess of hme is advisable in solutions 

 of them. There is probably no adequate reason for the abandonment 

 of lead in favour of calcium arsenate for orchard work. 



Nicotine sulphate is a powerful repellent for tent caterpillars, and 

 if feeding does take place, even weak solutions kill almost instantly. 

 It is an effective ovicide for codhng moth, especially with the addition 

 of soap, but is not to be recommended as a substitute for the standard 

 arsenate sprays in codhng moth control ; though it may prove highly 

 efficient as a substitute for the arsenate spray in the July apphcation 

 where a serious summer reinfestation of Aphids is present or again 

 in combination with the last summer apphcation of arsenate with a 

 spreader, as a further insurance against the damage caused by the last : 

 brood of larvae. |l 



WiMSHURST (C. E.). A Note on the Wheats and Barleys of Mesopo- 

 tamia, together with Observations on Local Conditions. — Agric. 

 Directorate, Mesopotamia, Basrah, 1920, 19 pp., 7 plates. TRcceived . 

 5th July 1920.] 



Among the common pests of wheat and barley in Mesopotamia are 

 wireworms, which, however, do not cause a great deal of damagei 

 Grasshoppers cause very variable and sometimes extremely serioi 

 losses, Decticus albifrons waits until the ears of wheat and barley arl 



