372 



Malenotti (E.). Venti Anni di Lotta contro la Mosca delle Olive in 



Italia. [Twenty Years of Work against the Olive Fly in Italy.] 

 — Nuovi Ann. Minist. Agric, Rome, i, no. 2, 31st December 

 1921, pp. 348-390. [Received 16th May 1922.] 



This paper reviews the work done in Italy in combating Dacus 

 oleae, Rossi, since 1901, chiefly along the lines of poisoning the fly 

 or of importing its natural enemies. The various modifications under- 

 gone by the poison methods are traced down to the present time, 

 when they have reached a stage of real practical value and only 

 require co-operation in their application to ensure excellent results. 



Malenotti (E.). Sulla Biologia del Dacus oleae Rossi. (Alcune 

 Osservazioni ed Esperienze eseguite in Maremma Toscana.) [On 



the Biology of D. oleae. Some Observations and Experiments 

 made in the Maremma District of Tuscany.] — Reprint from 

 Redia, Florence, xv, 28th January 1922, 12 pp. [Received 16th 

 May 1922.] 



In October 1921 an outbreak of Dacus oleae, Rossi, occurred near 

 Pisa, which was so severe as to result in an almost total destruction 

 of the olive crop in that locality, with a loss of about £100,000 at par. 

 The outbreak was favoured by abundant summer rains, which rapidly 

 developed the fruits, and by the prolongation of the hot weather 

 into October, which accelerated the development of the fly and the 

 appearance of its second and third generations. The severity of the 

 outbreak led to its rapid check, the adults of the third generation 

 being about one-third smaller in size than the normal, because 

 the larvae had to feed on fruits already damaged by the first two 

 generations. 



One experiment showed that though the larvae have no eyes they 

 are markedly photophobic. 



Some trees scattered among the others were covered with a sooty 

 fungus {Capnodmm) and were infested with a scale, Saissetia oleae, 

 and ants, Camponotus ligniperda var. pubescens. The relation between 

 the fungus and the scale was evident, while that existing between 

 them and the trunk-infesting ants was established by destroying 

 the nests of the latter, when they both disappeared. It is obvious 

 that the ants protected the scales against predacious and parasitic 

 enemies. This triangular relation was complicated by the presence 

 of D. oleae, which infested these trees more than the others, not being 

 attracted by the fruit, which was almost absent, but almost certainly 

 by the sugary secretions of the scales. The latter were therefore 

 responsible for the fungus and for a larger number of flies. Finally, 

 the presence of the flies benefited the ants, which were several times 

 seen capturing them and bearing them off to their nests. Several 

 hundred flies a day must be accounted for by the workers from each 

 nest, which is thus quite as much a focus of attraction and destruction 

 as a poison-bait trap. An experiment once more confirmed the fact 

 that dilute molasses is attractive to D. oleae, though the sooty fungus 

 seemed to be still more attractive. 



By 26th December no more adults were visible on the trees. Of 

 400 olives gathered on that day, 327 (81-7 per cent.) were infested. 

 Of these, 282 (86-3 per cent.) were recent infestations, of which 64 

 (22-7 per cent.) were " healthy " infestations, while in the remaining 

 218 olives the infestation had been stopped by various causes, parasites 



