542 



Prederichs (K.). Untersuchungen uber Rapsglanzkafer in Mecklen- 

 burg. [Investigations on Meligethes spp. in Mecklenburg.] — 

 Zeitschr. f. angew. Entmn., Berlin, vii, no. 1, September 1920, 

 pp. 1-36, 13 figs., 2 plates. 

 Investigations carried out in 1919 and further observations during 

 the first half of 1920 in Mecklenburg, where rape is grown on a large 

 scale, are recorded. The ordinary rape beetle, Meligethes aeneus, of 

 which the early stages are briefly described, and the less common 

 M. viridescens, together with CevtJwrrhynclivs assimilis, gall-midges, 

 etc., sometimes cause severe crop losses. It is difficult to say whether 

 Meligethes or Ceuthorrhynchus is the worse pest, but the presence of the 

 former is more apparent. 



The feeding habits of Meligethes are dealt with in detail. After 

 rape has flowered, the beetles have at their disposal Reqjhanistrum, 

 Sinapis arvensis, Raphanus sativus, etc., and in July, Sinapis alha. 

 During August they begin to migrate to the ground, where they 

 hibernate. It is doubtful whether any larvae hibernate. The egg- 

 stage lasts 4 days, the larval feeding period 8-12, the larval rest period 

 8. and the -pupal stage 11-12. To this total of 31-36 days must be 

 added the rest period of the adult 9-14 days, the total life-cycle above 

 ground thus requiring 40-50 days. As regards the number of 

 generations, the author was at first of opinion that in Mecklenburg 

 there are two generations, the first swarming in the second half of 

 June, and the second hibernating and mating in the following year ; 

 but in a supplementary note he inclines to the view that only one 

 generation occurs annually, as neither he nor others have succeeded in 

 breeding a second. 



The injury done by the adult becomes noticeable when the cruciferous 

 plants begin to flower. If the beetle appears when the plants are in 

 fufl bloom, it often eats the nectaries when feeding on the pollen and 

 sucking the nectar^ but no further injury 's done. If it appears early 

 it makes its way through the buds in search of the pollen and destroys 

 them. 



Larval injury is of less importance, and is worthy of note only when 

 the adults have been 'particularly harmful. In such cases of severe 

 infestation, when food becomes scarce at the close of the flowering 

 period, the young flowers are injured or even destroyed by the larva, 

 though usually a pollen-feeder. It may even attack the shoots and the 



stems. 



The few natural enemies of Meligethes include Coccinella septem- 

 pimctata, Malaclmis hipustulatus and an Ophionine parasite, Isurgus 

 heterocerns, Thorns. The latter plays an important part in checking 

 infestation, and is probably the parasite found by Oberstein in 1919 

 and recorded by him as ThersiloeJius morionellus, Holmgr. [R.A.E., A, 

 vii, 354]. The beetle larvae are protected so long as they are in closed 

 buds. Details of this parasitism are given. 



Falck (E.). Die Resinolbruhe als Spritzmittel zur Bekampfung 



tierischer Schadlinge. [Resinol Solution as a Spray against 



Insect Pests.] — Zeitschr. f. angew. Etitom., Berlin, vii, no. 1, 



September 1920, pp. 37-47. 



The alkah and alkahne-earth salts of the phenol-aldehyde resins are 



•easily soluble in water, and if concentrated to contain 33 per cent, of 



