508 



the 2nd of August, when both were found to be dead. The next year 

 the experiments were repeated, mushn being used instead of the metal 

 gauze, xit the end of August one of the trees was felled. The egg- 

 galleries were then 2-6 ins. long and their number did not suggest 

 that any other bark-beetles had been attracted to the tree. No larval 

 galleries were developed, but undeveloped eggs were found here and 

 there in the galleries. The walls of the egg galleries were quite hard 

 and polished, as if impregnated with resin, and were excavated between 

 the dead and the living part of the bark, the latter and the cambium 

 behind it being killed. That the trees themselves were not killed on 

 this occasion is thought to have been due to the bark-beetles being 

 too few. In 1915, at the beginning of June, the experiments were 

 again repeated on eight trees. On the 15th of July the bark surrounded 

 by the muslin was quite dead and by the middle of August all the trees 

 were killed. 



Iragardh (Ivar). Manniskans andel i insektharjningarnes uppkomst. 



[The part played by man in the origin of insect ravages.] — Ymer, 

 Stockholm, 1916, no. 3, pp. 273-281. 



This is a popular treatise on the methods by which man has himself 

 brought about the ravages of insects. When a plant was first cultivated, 

 it is probable that all insects dependent on it increased enormously, 

 with disastrous results. The same will doubtless occur again when- 

 ever a wild plant comes under cultivation. In many instances by 

 exterminating wild plants man has driven the insects feeding on 

 them to attack closely related cultivated plants, as happened when 

 the Colorado beetle [Leptinotarsa decemlineata] became a pest of 

 the potato; when Thecla melinus in the U.S.A., which originally 

 lived on Astragalus mollis, became a pest of beans, peas, cotton and 

 maize ; and when Bruclms brachialis, which in the South of Europe 

 lived on wild species of Vicia, attacked Vicia villosa at the beginning 

 of this century in France. The pests of one country have been intro- 

 duced into others by the agency of man, as in the case of Phylloxera, 

 the gipsy moth [Lymantria dispar], the brown-tail moth [Euproctis 

 chrysorrhoea], the fruit fly [Ceratitis capitata], and other insects. The 

 author summarises the instances where the biological method of 

 controlling insect pests has been successfully applied, instancing the 

 case of the cottony cushion scale [Icerya purchasi] in California, 

 Marlatt's voyage round the world in search of the natural enemies of 

 the San Jose scale [Aspidiotus 'perniciosus], and Silvestri's voyage to 

 Africa on behalf of the Government of Hawaii in search of the enemies 

 of Ceratitis cap^itata. 



TuLLGREN (Albert). En ny strit, TyjMocyba Bergmanni, n. sp., fran 

 Norge. [A new leaf-hopper, Typhlocyba bergmonni, sp. n., from 

 Norway.] — Entomologisk Tidshrift, Stockholm; 1916, pp. 64-69, 

 Ifig. 



A detailed description is given of Typhlocyba bergmanni, sp. n., found 

 on Mauken, east of Trondhjem. This Homopteron appeared on a 

 road at the beginning of August in countless numbers, where it was a 

 serious nuisance to travellers. It is said to be closely related to 

 T. hippocastani, Edw, 



