I4S JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Mealybug, The Common, and its Control in California. By R. S. Woglum 

 and J. D. Neuls (U.S.A. Dep. Agr., Bur. Entom., Farm. Bull. 862, Sept. 1917; 

 4 figs.). — This bulletin discusses the three remedies which have been widely 

 used — i.e. fumigation, spraying, and the artificial spread of insect enemies. 



V. G. J. 



Melicytus ramiflorus Forst. By S. A. Skan (Bot. Mag. t. 87635 1918). — 

 Violaceae. Native of New Zealand and Polynesia. A shrub of considerable size 

 for the temperate house. The leaves are 2 to 6 inches long, oblong-lanceolate 

 with a serrate margin, polished dark green above, paler beneath. The flowers 

 are inconspicuous, born in axillary clusters and pale yellowish-green in colour. 

 The fruit is a violet-blue, depressed globose berry £ to | inch across. — L. C i E t 



Mesembryanthemum edule Linn. By R. A. Rolfe (Bot. Mag. t. 8783 j 

 1 91 8). — Native of South Africa. A handsome succulent which requires the 

 protection of a greenhouse in winter. It grows best when planted along the 

 top of a low wall and allowed to hang down \ a poor sandy soil suits it best and 

 it can be propagated by cuttings taken at any time of the year. The flowers 

 are about 3 inches across, yellow when first open, changing later to flesh colour. 



L. C. E. 



Mesembryanthemum Elishae N. E. Br. By R. A. Rolfe (Bot. Mag. t. 8776 b j 

 191 8). — Native of South Africa. A member of the section ' Cordiformia,' in which 

 the leaves are very fleshy and somewhat elongated, more or less united at the base 

 but free above. The leaves are glaucous green, with scattered darker dots. 

 The flowers are bright yellow, £ inch across. — L. C. E. 



Mesembryanthemum fulviceps N. E. Br. By R. A. Rolfe (Bot. Mag. 8776a, 

 1918). — Native of South Africa. A member of the ' Sphaeroidea ' section of 

 the genus, in which the leaves are reduced to a single pair, united to form a 

 globose mass termed a ' corpusculum.' Flowers about an inch across, yellow 

 tipped with orange. — L. C. E. 



Monadenium erubeseens N. E. Brown. By O. Stapf (Bot. Mag. t. 87563 

 191 8). — Euphorbiaceae. Native of East Africa. A plant which grows well in 

 a warm succulent house, under the treatment suitable for species of Stapelia. 

 It has a perennial globose tuber 8 to 14 inches in diameter. One to two stems are 

 produced from each tuber bearing rather fleshy leaves, green above, reddish 

 with green veins beneath. The inflorescence is reduced to a solitary drooping 

 cyathium surrounded by involucral bracts. The bracts are united to the middle 

 to form a bell- shaped cup, white, finely veined with green, tinged with rose 

 towards the base. Cyathium pale green cleft on one side to the middle, sur- 

 rounded by a thick yellow annular gland. The male flowers are naked mixed 

 with fimbriate bracteoles, female flower drooping exserted from the cleft of 

 the cyathium. — L. C. E. 



Mosquito Larvae, The Effects of Petroleum Oils on. By S. B. Freeborn and 

 R. F. Attsatt (Jour. Econ. Entom. vol. xi. June 1918, pp. 299-308). — The authors 

 enumerate six theories, including their own, which have been advanced in explana- 

 tion of the lethal effect of petroleum oils on mosquito larvae. The experiments 

 are arranged and tend to prove the contention that it is the oil vapour from the 

 inspired oil through its extremely rapid penetration of the tracheal tissues that 

 is mainly responsible for the lethal action. The work was originally undertaken 

 to check the recommendation of the entomological division of the University 

 of California, of a mixture of crude oil and kerosine in equal proportions as the 

 best for oiling (Baume 28 0 to 32 0 ). 



The conclusions reached are : The toxicity of the petroleum oils as mosquito 

 larvicides increases with an increase in volatility. The volatile constituents are 

 responsible for the primary lethal effects, by penetration of the tracheal tissue. 

 In the heaviest oils (boiling point greater than 250 0 C.) this action may be 

 secondary to the purely mechanical suffocation by the plugging of the tracheae. 

 The paper concludes with a bibliography. — G. W. G. 



Mushroom Pests and how to control them. By C. H. Popenoe (U.S.A. 

 Dep. Agr., Bur. Entom., Farm. Bull. 789, Feb. 1917; 7 figs.). — The insect pests 

 that usually attack cultivated mushrooms are mushroom maggots (the larvae 

 of small, gnat-like flies), mites, spring-tails, and sow-bugs or woodhce. All 

 windows and ventilators of mushroom houses should be covered with fine wire 

 gauze, which prevents the entrance of the fungus gnats. 



Mushroom spawn should only be purchased from reliable dealers. — V, G. J, 



