499 



months this weevil can have a short one of 3-4 months; this has 

 been described by Escherich, from the Bienwald, Rhine Palatinate 

 [R.A.E., A, ix, 156]. In the Bienwald, larvae hatch in about 

 10 days from eggs deposited in April-June by hibernated females 

 in pine stumps from fellings during the winter. These larvae 

 bore in the cortex and sapwood of the roots and are full-grown 

 in 2-3 months. Some hibernate in the larval stage and yield 

 adults after a pupal stage of 14 days in July in the following year. The 

 others develop rapidly ; they pupate in August and after 14 days yield 

 adults that hibernate. Therefore eggs deposited in spring derive from 

 eggs deposited either one or two years before. Furthermore, eggs in 

 spring are also deposited by old' individuals of the long-cycle {i.e., 

 those first hibernated as larvae) that have already oviposited in the 

 preceding year. Escherich ascribes this variation in the length of the 

 life-cycle to changes in temperature. The author suggests that the 

 date of oviposition is an additional factor. Larvae hatched early 

 (April) are most likely to transform into adults in the same year, while 

 those hatched later probably hibernate before pupating. The author 

 has never, however, noticed that larvae hatched in late summer require 

 about 22 months (two hibernations) for development, as stated by 

 Grohmann in Saxony [R.A.E., A, ii, 326]. The temperatures in the 

 various districts appear to influence development very markedly, 

 and Grohmann does not appear to have found the short-cycle generation 

 in his experiments. These points afford a partial explanation of 

 the seemingly contradictory data on the length of development of 

 H. abietis. 



Of the Nematode parasites of the weevil, Allantonema mirahile 

 has been closely investigated. Its reproduction seems to be an unbroken 

 succession of autogamous hermaphrodites. It is the young weevil 

 larvae that seem to acquire the infestation, which becomes less probable 

 as the larvae penetrate deeper into the tree stumps. The effect of the 

 infestation is negligible as regards natural control of H. abietis. Weevils 

 harbouring numbers of adult and larval Nematodes did not appear to be 

 in the least affected and, contrary to previous statements, retained 

 their power of reproduction unimpaired. 



As regards Hymenopterous parasites the author only once found 

 some undetermined specimens in material comprising 800 adults and 

 400 larvae and pupae. F. Eckstein has found Syrphid larvae in the 

 mines of the weevil [R.A.E., A, viii, 406], and Grohmann has recorded 

 a number of Arthropod enemies [A, ii, 326]. Of Protozoa, only Gregarina 

 kylobii is known from H. abietis ; it is harmless. Some birds feed on the 

 adult weevils, but the larvae in the underground roots are well protected 

 against them. Mechanical control, which usually satisfies the forester's 

 requirements, is directed against the adults, unless the costly uprooting^ 

 of stumps is resorted to. 



Dingle R (M.). Ueber Versuche mit Sprengungen zur Engerlings- 



bekampfung. [Experiments in Blasting as a Measure against 

 Cockchafer Larvae.] — Zeitschr. angew. Ent., Berlin, viii, no. 2, 

 May 1922, pp. 421-426, 3 figs. 



Experiments in destroying the larvae of cockchafers [Melolontha] by 

 blasting with explosives, used both alone and with the addition of poisons 

 including chloropicrin, gave unsatisfactory results. This appears due 

 to the depth (below the level where the larvae occur) at which it was 

 necessary to lay the charges in order that their effect should not be 



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