230 



The chemical investigation of a number of trees shows that gum 

 production is the forerunner of lac production, and probably that 

 tannins are the preciirsors of gums. Gum production is not exactly 

 a healthy condition and semi-dryness in the trees stimulates the 

 growth of gum bacteria. Consequently semi-dry trees are those that 

 ultimately produce food for the insect. This condition of the trees 

 may be induced in various ways, by the chemical composition of the 

 soil, and by ground fires and various methods of spacing, both of 

 which affect the tree directly and also affect the chemical composition 

 of the son. 



It is emphasised that systematic cultivation of lac should replace 

 the casual collection of it in the more or less wild state. 



WoGLUM (R. S.). U.S. Bur. Entom. Practical Fumigation with 

 Liquid Hydrocyanic Acid. — The California Citrograph, [sine loco], 

 iv, no. 10, August 1919, p. 284. [Received 1st April 1920.] 



New dosage schedules producing a greater uniformity of results are 

 given to take the place of those originally prepared [R.A.E., A, 

 viii, 29], together with a method of calculating the amount of 

 material used in practical work. 



WoGLUM (R. S.). U.S. Bur. Entom. The Value of Weather Records 

 in Fumigation. — The California Citrograph, [sine loco], v, no. 4, 

 February 1920, p. 110, 2 figs. 



The effects of atmospheric conditions on the results of citrus 

 fumigation are many and complex. The temperature desirable 

 depends on the locahty. Humidity tightens the tent cloth, causing 

 a greater concentration of gas over a longer period ; but the dragging 

 of heavy wet tents over wet fruit tends to skin abrasion with 

 subsequent pitting and scorching from the gas. Certain injury 

 seems due to low barometric pressure, but sufficient data have not yet 

 been collected on this point. A shght wind produces uneven gas 

 concentration, a strong wind clears it from the tent. Hot sunshine is 

 injurious. A series of instruments suitable for use in field work is 

 mentioned. 



Metcalf (Z. p.). Report of Entomologist. — 41st Ann. Repf. North 

 Carolina Agric. Expt. Sta. Year ended 30lh June 1918, Raleigh, 

 30th June 1918, pp. 45-49. [Received 1st April 1920.] 



The gloomy scale {Chrysomjihalus tenehricosus) is the most destruc- 

 tive pest of maples in CaroHna. A Hymenopterous parasite infests it, 

 kilhng as many as 98 per cent. , but, unfortunately, its appearance is 

 very sporadic. Spraying must therefore be the chief measure in 

 control, soluble oils being the most suitable for this purpose. One 

 application of a strong mixture during the winter is often efficacious. 



Bean and pea weevils {Bruchus spp.) should be treated by storing 

 the seed in air-slaked lime, or the weevils can be killed by heat. The 

 amount of lime varies ; for less than a gallon of seed, four times as 

 much lime as seed should be used and thoroughly mixed in. For 

 amounts up to two or three bushels the same quantities of lime and 

 seed should be mixed; up to 25 bushels one-half as much lime is 



