junei2, i9i6 Bacterial Wilt of Cucurbits 419 



vines which had been diseased for a long time. Doubtless few living 

 organisms were present, since great difficulty was experienced in obtain- 

 ing cultures of B. tracheiphilus from this field (strains En 102 and Em 10). 

 The beetles used in experiment 4 were collected when hibernating in a 

 field where wilt was known to have occurred, but it is evidently not pos- 

 sible to determine whether they had fed upon wilted plants. On the 

 other hand, it is not reasonable to assume that all beetles which have 

 fed upon wilted plants would necessarily be able to carry infection 

 on their mouth parts for any great length of time. Experiments i 

 and 2 show that at least in some cases the striped beetles may 

 carry the wilt organism for at least five or six weeks and still be able 

 to infect healthy plants. This, in connection with the field experiments 

 previously published,^ seems to establish beyond doubt that D. mttata 

 is a winter carrier of the cucurbit organism.^ Experiments with other 

 species of insects have thus far given negative results, as here detailed. 



In each of seven tests carried out with the common squash bug {Anasa 

 irisiis DeG.) during the summer and fall of 191 5 in field and greenhouse, 

 two to six of these insects were fed for one to three days on wilted cucum- 

 ber leaves and petioles and then inclosed with several healthy cucumber 

 plants. After feeding on these plants for one to two days the bugs 

 were removed and the plants kept under observation for three to four 

 weeks. No wilt appeared in any of these plants, but no absolute con- 

 clusion can be drawn from the negative results of so small a series of 

 tests. 



The twelve-spotted (or squash) lady beetle (Epilachna borealis Fab.) 

 was very scarce in eastern Long Island during the season of 191 5, but 

 two tests with it similar to those outlined above gave negative results. 



The melon aphis (Aphis gossypii Glov.) and the flea beetle (Crepidodera 

 cucumeris) apparently do not serve as wilt carriers. This has been 

 shown by the negative results from transfer of insects fed upon wilted 

 plants to healthy cucumber plants in insect-proof cages (three tests), 

 and b}^ the fact that no wilt developed during the season in cucumber 

 plants grown in 48 large screened cages (East Marion, Eong Island, N. Y., 

 191 5), although numerous wilted plants occurred around all of these 

 cages, and aphids and flea beetles had free access through the meshes 

 of wire netting and were abundant both outside and inside the cages. 



In only 2 out of 50 cages did wilt appear and in these cases striped 

 cucumber beetles had gained access or had been purposely introduced, 

 and the disease had started from points gnawed by the beetles. 



' Rand, F. V. Op. cit. 



2 Wild cucurbits may be eliminated as possible carriers of bacterial wilt so far as the experiments at 

 East Marion are concerned. Personal observations, together with those of Bumham and Latham 

 (Bumham, Stewart H., and Latham, Roy A. The flora of the town of Southold, Long Island and Gar- 

 diner's Island. In Torreya, vol. 14, nos. 11-12, 1914), and a search through the herbaria of the Xcw York 

 and Brooklyn Botanical Gardens, have established beyond doubt that no wild Cucurbitaceae occur within 

 10 to 15 miles of the experimental plots. 



