276 



to complete the gallery and each female lays about 14 to 24 eggs. 

 The mother gallery usually takes the form of a circular burrow round 

 the base of a branch or twig, and weak branches may be completely 

 girdled. The larval galleries run almost at right angles to the mother 

 gallery, the larvae boring alongside the mother gallery at first and 

 separating later to gnaw the inner bark layers. The mother galleries 

 never penetrate the sap-wood, and the larval galleries as a rule do not 

 groove the sap-wood until the insects are just about to pupate. If 

 the branch is very thick pupation may take place in the bark. The 

 larvae feed for about 69 days before pupation, the pupal stage lasting 

 about 22 to 29 days. The young beetles feed on the bark surrounding 

 their pupal bed, gradually boring through it to effect an exit. The 

 length of the adult stage and number of generations in the year has 

 not been definitely ascertained. It is probable that after oviposition 

 the female enters another period of feeding and a second pairing and 

 egg-laying take place. Sometimes the females die after oviposition. 

 In Scotland C. abietis usually breeds in the stems, branches and 

 twigs of unhealthy, dying or dead trees of Abies, Picea and Pseudotsuga. 

 Trees of the genus Abies, especially A. pectinata, seem to be preferred, 

 the others only being normally attacked in their absence. On the 

 continent of Europe C. abietis seems to prefer Picea spp., although it 

 is known to attack other genera of conifers. So far this beetle has 

 not proved destructive to living trees. Attention is called to the fact 

 that the adult beetles, being negatively heliotropic, prefer for brood 

 purposes twigs of branches in shady places. The natural enemies 

 of the larvae include a Chalcid that has been known to destroy 75 

 per cent, of them. Only one parasitic larva is found on each host. 



Green (E. E.). A list of Coccidae affecting various Genera of Plants. 



— Ann. Ajp'p. Biol., Cambridge, v, nos. 3 and 4. April 1919. pp. 

 261-273. 



This paper forms the concluding part of the author's list of Coccids 

 and their food-plants [see this Review, Ser. A, vii, p. 70, etc.]. 



It is noted that the Gramineae, including the bamboos, have a 

 special Coccid fauna comprising such genera as Antonina, Aclerda, 

 Eriopeltis, Lecanopsis and Odonaspis. The Coniferae have a monopoly 

 of the genus Physokermes, while Kermes is confined to species of 

 Quercus. 



Among those Coccids that have the largest number of food-plants 

 are Pseudococcus citri, Coccus {Lecanium) hesperidum, Lepidosaphes 

 idmi and Aspidiotus hederae. 



Chittenden (F. H.). The Sweet Potato Weevil and its Control.— ?7./S. 



Dept. Agric, Washington, D.C., Farmers' Bull. no. 1020, January 

 1919, 24 pp., 13 figs. [Received 6th May 1919.] 



Cylas formicarius, F., is becoming very destructive and threatens 

 to invade all States where sweet potatoes are grown. The importance 

 of this crop may be gauged from the fact that the value of that for 

 1918 was estimated at over £23,000,000, while the loss in several States 

 has amounted to from 10 to 20 per cent. The life-history and the 

 usual measures against this weevil are discussed [see this Review, 

 Ser. A, vii, p. 21, etc.]. 



