262 



first being more common in Natal and the latter in the Cape Province. 

 Both species occm- in the Transvaal, where, however, C. capitata is 

 Xisually much the more abmidant. These pests are to a certain extent 

 checked by predaceous insects, which destroy them as they fall to 

 the ground jjreparatory to pupating in the soil. 



Elective control can be exercised by the use of poison-bait, which 

 consists of a light sprinkling of sugar water poisoned with, lead arsenate. 

 This should be apphed early, and in the Transvaal needs to be repeated 

 at shoi-t intervals, owing to the frequency of summer rains. Previous 

 to the value of this remedy being proved, the only means of com- 

 bating the pest lay in surrounding the fruit, or the whole tree with 

 cotton netting, 20,000 yards, at a cost of about one penny a square 

 yard, having been sold to fruit growers in 1898. 



Rabaud (Et.). Les Chenilles Parasit6es de Zygaena occifanica, Vill. 

 [Parasitised Larvae of Zygaena occitanica, Vill.]. — Bull. Sci. 

 France et Belgique, Paris, 1, 1916, no. 3, 10th February 1917, 

 pp. 284-286. 



It has been asserted that parasitised Lepidopterous larvae behave 

 in a different manner from healthy ones, aimlessly leaving their 

 natural habitat, or even pupating in situations peculiarly suited to 

 their parasites. These statements seem to be based on the fact that 

 all larvae before moulting or pupating cease to feed and either wander 

 about on their ow^l food-plant or even abandon it. The latter is the 

 case with the larva of Zygaena occitanica, which, whether healthy 

 or j)arasitised, always leaves its host-plant. Though the fact of its 

 being parasitised may hasten these physiological changes, it certainly 

 does not cause them. 



From cocoons of Z. occitanica. taken in a normal situation, the author 

 has reared three Diptera : — Tricholyga major, B.B., Compsilura 

 concinnata, Mg., and Blej^haromyia jjagana, Mg., the same cocoon con- 

 taining two or three pupae of the same or even different species ; and 

 three Hymenoptera : — Atrotnetus insignis, Forst., Monodontomerus 

 dentipes, Wallv., and Spilocrypt'us sp. 



Chamberlin (W. J.). Bark-beetles Infesting the' Douglas Fir. — 

 Oregon Agric. Expt. Sta., Corvallis, Bull. no. 147, January 1918, 

 40 pp., 15 figs. [Received 5th April 1918.] 



About 30 per cent., or 650 bilHon feet, of the standing coniferous 

 timber in the XJnited States is Douglas fir {Pseudotsuga t/ixifolia). 

 Wherever commercial timber is grown in North America, it is the 

 dominant tree and is undoubtedly destined to be the leading com- 

 mercial tree of the future. The estimated amiual loss to forests and 

 forest products in the United States due to insects is approximately 

 £20,000,000,- and since Oregon contains one-fifth of the standing 

 timber of the United States, the loss in that State is reckoned at 

 approximately £4,000,000 annually. The present bulletin records the 

 results of over two years' study of the life-histories and economic 

 importance of the pests dealt Math. 



A key is given to the species of Scolytids concerned. These include 

 Cryphalus amabilis, Chamb., which damages Abies amahilis and 



