NOTES AND ABSTKACTS. 



819 



Insect Injuries to Forest Trees. By A. D. Hopkins (U.S.A. Dep* 

 Agr. Year Booh, 1903, p. 313 ; plates). — The characters of insect injuries 

 to living forest trees are discussed under two heads : (1) Injuries which 

 cause the death of the trees ; (2) Injuries to the wood which do not 

 materially affect the vitality of the trees. Under the first head are 

 included injuries by bark-beetles and bark-boring grubs. The Hickory 

 bark-beetle (Scolytus A-spinosus Say) is a short, stout, shining black or 

 reddish- brown beetle, averaging 0*14 inch in length. It appears on the 

 wing from May to August, and attacks the base of the buds and leaves 

 for food, afterwards depositing its eggs in the bark. Illustrations ar6 

 given of the burrowings in the bark. The method recommended for 

 combating the insect is the cutting and burning of the infected trees 

 before the broods of the beetles commence to emerge. 



Bark-beetle injuries to Oak trees are dealt with. This beetle (Pityo- 

 phthorus pruinosus Eichh.) is an exceedingly small one, less than -08 of an 

 inch in length, which sometimes occurs in such vast numbers that large 

 Oak trees are attacked and killed by it in a few weeks. The writer advocates 

 the removal and burning of the infested bark and small branches in the 

 winter. 



Amongst the insect injuries to the wood of living trees mentioned, the 

 pinhole injuries in Oak wood may be referred to. One of the most destruc- 

 tive of this class of enemies of hardwood forest trees is the Oak timber 

 worm (Eupsalis minutd). This is a slender whitish worm, less than an 

 inch long. The eggs are deposited in a wound in the tree, and the young 

 larva- bore the pinholes until they emerge the following spring as adults. 

 It is suggested that all dead, standing and felled, Oak trees and old logs 

 should be cleared away from living trees, and all unnecessary axe and other 

 wounds avoided. — V. J. M. 



Insectivorous Plants, Researches on the Anatomy, Develop- 

 ment, and Biology of the Foliage-leaves and Glands of. By 



C. A. Fenner (Flora, xciii. 1904, pp. 335-434, vi.-xxi). — This deals 

 with the following plants : — Pinguecula vulgaris L., Sarracenia flava 

 L., Nepenthes Bafflcsiana Jack, Aldrovanda vesiculosa L., Byblis 

 gigantea Lindl., Boridula gorgonias Planch., Droscra rotundifolia L., 

 Drosophyllum lusitanicum Lk. The most interesting novelty is the proof 

 that Sarracenia secretes a digestive enzyme ; and that at the base of the 

 pitchers is a zone of absorbent cells, whose nuclei are fragmented and lie 

 in niches separated by cellulose bars. The histology and histogenesis are 

 treated exhaustively, and the physiological researches on Droscra are 

 singularly interesting, showing that the secretion of the sessile glands is 

 accelerated directly by the secreted substance of the stalked glands, and 

 indirectly by the internal stimulus transmitted when the latter are stimu- 

 lated. Plate ix. is lettered and placed as " t. xiii." and vice versa. — M. H. 



Insect Pests, Destruction of, by their Natural Foes. By 



G. T. Grignan (Bev. Hort. pp. 408-410, Sept. 1, 1904).— Some interesting 

 remarks on the introduction of exotic foes to introduced exotic vermin 

 in America. The San Jose scale (Aspidiotus perniciosus), for instance, 

 being confronted with its enemy Chilocorus similis, discovered by 



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