470 



Compere (G.). Origin of Fumigation with Hydrocyanic-acid Gas in 

 California. — Mthlv. Bull. Cal. Dept. Agric, Sacramento, xi, 

 no. 5-6, May-June 1922, pp. 438-442, 2 figs. 



The history of hydroc^'anic acid gas fumigation for the control of 

 Iceyya piirchasi, Mask, (cottony cushion scale) in Cahfornia is reviewed. 

 With the discovery and introduction of the i\ustrahan Coccinellid, 

 Novius [Vedalia] cardinalis, which has proved an effective check on 

 the scale, further experiments with artificial methods ceased. 



EssiG (E. O.). The Artichoke Plume Moth {Platyptilia BV.).—Mthly. 

 Bull. Cal. Dept. Agric, Sacramento, xi, no. 5-6, May-June 1922, 

 pp. 454-456, 1 fig. 



Tlie identity of the species concerned is somewhat doubtful. It has 

 been determined from reared adults as Platyptilia acanthodactyla, Hb., 

 by Tate, this species being found both in Europe and the United States, 

 but the coloration of the larvae differs from that of the overwintering 

 individuals collected by the author, which resemble more those of 

 P. carduidactyla, Riley. It is possible that more than one species may 

 be involved, and it is hoped definitely to settle the identity during the 

 coming season. The larvae are particularly active and injurious during 

 March, April and May, the developing heads of the artichoke being 

 their favourite food, but they will also eat into the stems or bracts 

 and portions of the leaves. Pupation begins in April. There are at 

 least two broods in the year, possibly three or four. The maximum 

 emergence of adults occurs in September according to Tate, who has 

 also found the larvae feeding on European milk thistle [Silyhum 

 marianum), which occurs generally along the coast region of the State. 



Light traps may be used to great advantage for the adults in April, 

 May and June, and again in August and Septemiber. Various methods 

 for the control of the larvae are being tried. In this connection it is 

 suggested that the thistle food-plants should be removed in the spring 

 and kept down throughout the year. The refuse remaining after the 

 artichokes are cut down should be ploughed under very deeply or 

 destroyed. Sprays, consisting of 2 lb. powdered zinc arsenite or 3 lb. 

 powdered lead arsenate to 100 U.S. gals, water, or f U.S. pint 40 per 

 cent, nicotine sulphate to 100 U.S. gals, water with 5 lb. fish-oil soap 

 as a spreader, may prove effective in controlling the larvae. The dusts 

 suggested for experiments are 1 part powdered zinc arsenite or 

 powdered lead arsenate to 3 parts hydrated lime, or 5 per cent, and 

 10 per cent, nicodust or nicotine dust. 



If the sprays and dusts are applied immediately after picking, 

 the small developing buds may be coated without danger to the 

 consumer ; at this period the larvae are generally in the leaf axils at 

 the bases of the buds or feeding on the outside of them. 



EssiG (E. O.). Nematodes attacking Dahlia Tubers. — Mthly. Bull. 

 Cal. Dept. Agric, Sacramento, xi, no. 5-6, May-June 1922, 

 pp. 465^66, 1 fig. 



Nematode infestation of dahlia tubers may be easily overlooked. 

 A brief account is given of the appearance of diseased tubers and the 

 best method of determining such infestation. 



