76 



One orchardist reported that some success was attained by the use 

 of stick}^ fly paper, the flies being attracted to anything shining', such 

 as a straw hat. 



A perfectly effectual method of preventing attack by a fruit fly in 

 south Africa, but one which would scarcely be used save in the case 

 of the most valuable trees, consisted in inclosing the entire tree above 

 the trunk in a flne-mesh mosquito netting during the time when flies 

 are abundant. 



It is quite possible that Morello and Montmorency cherries might 

 be grown in districts where these flies are abundant, as traps to lure 

 the insects from other varieties of trees. This method is certainly 

 worthy of trial. On these trees the fly paper could be used, and con- 

 siderable expense could thereby be saved. 



Finally, would-be growers of cherry, in the regions which have been 

 noted as the seat of the principal outbreaks of this fruit fly, are 

 cautioned against the planting of Morello, Montmorenc}', and similar 

 sour varieties as a main crop, owing to the greater liability of injury 

 by the pest. 



ON THE ORIGIN OF THE NATURAL COLORATION OF SILKS OF 



LEPIDOPTERA. 



By (t. Lkverat and A. Conte. 

 (Comptes Reiidns, dc l'Acad(''inie des Sciences, read October 27, 1902.) 



With most lepidopterous larvfv the product of the silk glands is not 

 colored. When it is colored it is 3ollowor green. We ask ourselves, 

 what is the origin of these green and yellow pigments? Are they 

 made by the animal or simply drawn from the leaf upon which it 

 feeds? The flrst of these hypotheses has been generally held since the 

 work of Alessandrini »Toly, R. Dubois, and L. Blanc have shown that 

 it was impossible for a coloring matter contained in the intestine to 

 reach the silk. The contrary results obtained by Bonafous, E. 

 Blanchard, Roulin, and Villon have been denied in an absolute man- 

 ner and stated to ])c the consequence of a soiling of the silk thread on 

 its exit from the spinneret. If the coloring matters employed so far 

 do not easily pass through the walls of the silk reservoir, is it the 

 same for all of the coloring principles and for all silkworms? It is 

 to respond to this question that we have undertaken our new experi- 

 ments. Our trials were carried on with a wild silkworm, Attacus 

 orlzaha^ and the domesticated silkworm {Bomhy.r mori)^ the French race 

 with yellow silk, and a polyvoltine race from China with white silk. 

 The coloring matters used were neutral red (toluylene red), methylin 

 blue, B. X., and picric acid. 



■ (1) Attacus ot'isaha. — Thirty larvaj born July 16, 1902, were divided 

 into several lots and raisc^d upon oak branches, of which the leaves 

 had been washed with an acpieous solution of coloring matter. 



