521 



Hegh (E.). Les Termites. — Bull. Agric. Congo Beige, Brussels, 

 xi, no. 3-4, September-December 1920, pp. 253-352, 65 figs., 

 and xii, no. 2, June 1921, pp. 353-441, 45 figs. 



These papers form the first two instalments of a monograph on the 

 termites of Tropical Africa, written with the object of making known the 

 methods of destroying them or preventing the damage due to them. 

 The present chapters contain a description of the principal morphological 

 and anatomical characters of these insects, and review their geographical 

 distribution and classification. The constitution of the population of 

 a termitarium is studied, and its biology and social life are discussed. 

 The food and fungus gardens of certain species are described, and the 

 construction of the nests explained. Later instalments will deal with 

 the relations of termites to other insects and to vegetation, their 

 natural enemies, parasites, etc. The termites occurring in the Congo 

 will be dealt with in one section, and the last instalment will discuss 

 methods of extermination and prevention of damage. It is intended 

 to include a complete list of African termites, with notes on each. 



Baker (A. C). The Practical Significance of the Revolution of the 

 Embryo in Aphid Eggs. — Science, Lancaster, Pa., liv, no. 1389, 

 12th August 1921, pp. 133-135. 



All Aphid eggs, no matter whether laid early or late, reach the 

 resting stage before wintering, and the embryo, especially of Aphis 

 pomi, De G., and A. sorhi, Kalt. {malifoliae. Fitch) remains in this 

 condition until early spring, when normal growth is resumed. This 

 takes place, in the vicinity of Washington, abdut the middle of ]\Iarch, 

 and is accompanied by the rupture of the envelopes and the revolving 

 of the embryo. An increase of temperature before revolution is fatal 

 to the embryo, whereas after revolution the eggs are more susceptible 

 to contact and similar injury. After revolution of the embryo, 

 hatching may be advanced or retarded by w^eather conditions ; and 

 high temperatures, which before revolution would have proved fatal, 

 only serve to hasten hatching unless the atmosphere is extremely dry. 

 After revolution the embryo is less protected by reason of the fracture 

 of the gelatinous matrix enclosing it, and as it is actively growing, it is 

 more susceptible to the effect of spray solutions. This may explain 

 the different results obtained in various spraying experiments. 



A. prnnifoliae hatches in much the same manner, but much earlier 

 than A. pomi and A. sorhi. The result is that whilst the latter 

 are in the critical period of embryonic development, and may be con- 

 trolled b}^ a lime-sulphur spray, ^4. pritnifoUae is in the first or rarely 

 the second instar, and may be easily killed by a nicotine spray. A 

 combined lime-sulphur-nicotine spray applied as a delayed dormant 

 treatment is therefore advocated for the control of these Aphids. 



Froggatt (W. W.). Fumigating Maize with Carbon Dioxide. — 

 Agric. Gaz. N.S.W., Sydney, xxxii, pt. 7, July 1921, p. 472. 



To protect shelled maize from weevils with carbon dioxide gas, 

 it should be placed in a tank and the gas introduced from a cylinder 

 at the rate of 1 lb. in three minutes for every 12 bushels of grain ; 

 a 500 gal. tank holds 60 bushels and should be treated with 5 lb. of 



(4557) Wt. P.3/184 1500 11/21 Harrow G. 75. 2M 



