303 



is worthy of attention, as it aims at aiding the natural development of 

 the fungus, not at producing artificial epidemics [see also this Review, 

 Ser. A, ii, p. 409]. The practical value of entomophytic fungi in 

 controlling insect pests is still undecided, and the problem of producing 

 at will a genuine epidemic which will spread of itself with sufficient 

 rapidity to kill insect pests before they are able to cause loss, still 

 remains unsolved. 



Entomophytic sporozoites have not been studied to the same extent 

 as the fungi. The most deadly epidemics caused by these micro- 

 organisms have affected the silk-worm and the honey-bee, Nosema 

 homhycis and N. apis being the respective sporozoites. Unsuccessful 

 attempts have been made to cause pebrine epidemics in Phylloxera 

 and among vine moths. Krassilstchik has reported a very deadly 

 epidemic among the caterpillars of Phlyctaenodes sticticalis, due to 

 Microklossia prima and M. apicnlata. These species seem to be widely 

 diffused among Lepidoptera, and Krassilstchik records Polia (Mamestra) 

 oleracea as being infested to such a degree in Kussia in 1902 that the 

 development of its usual Tachinid and Ichneumonid parasites was 

 rendered impossible. In 1907 Leger reported the presence of a new 

 Myxosporidium in the Tenebrionid beetle, Scaurus tristis, 01., from 

 Algeria. 



Entomophytic bacteria have also been but little studied. In 1892 

 Krassilstchik reported two diseases of the larvae of Melolontha melo- 

 lontJia in south Russia, viz : — Graphitosis caused by Bacillus tracheitis 

 si\e graphitosis, Krass., and septicaemia hj Bacillus septicus insectorimi. 

 Infection could only be conveyed by inoculation. Some years before, 

 Forbes had noted the existence in Illinois of a chinch bug disease due 

 to Micrococcus insectorum, and Metchnikoff, when studying the fungi 

 infesting the larvae of Anisoplia austriaca, found that many of them 

 succumbed to a bacterial infection due to Bacilhis salutarius. In 1911 

 d'Herelle reported a deadly bacterial epidemic among Schistocerca 

 pKilleyis (Mexican locust) in Yucatan (Mexico), and much work has 

 since been done with Coccobacillus acridiorum in Dalmatia, Turkey, 

 Tunisia, at the Cape, in Colombia, Venezuela, and elsewhere [see this 

 Review, Ser. A, i, pp. 162, 197 ; ii, pp. 95, 126, 335, 353, 462, 509, 681 ; 

 iii, pp. 63, 118, 211, 293, 339, 399, 503, 682, 670, 699 ; iv, pp. 14, 45, 

 46, 48] which seems to point to its usefulness as a supplementary control 

 to arsenicals. Chatton discovered Bacillus melolonthae in Melolontha 

 melolontha and B. homhycis in the silk- worm. In 1913 Picard and 

 Blanc discovered B. cajae and B. lymantriae in Arctia (Chelonia) caja 

 [see this Revieiv, Ser. A, i, p. 166] and Lymantria dispar [Ser. A. ii, 

 p. 422]. The present author discovered B. gortynae in caterpillars of 

 Xanthoecia flavago {Gortyna ochracea) and B. jvjrameis in caterpillars 

 of Pyrameis cardui [see this Review, Ser. A, i, p. 552]. 



The infections dealt with so far are due to known micro-organisms, 

 but there are others, of an important and epidemic character, regarding 

 the nature of which students are not agreed. The " grasserie " of 

 the silkworm and the polyhedral wilt disease of Lymantria monacha 

 (nun moth) belong to this category. In the United States Reiff 

 attempted the artificial transmission, on a large scale, of the wilt 

 disease (flacherie) to Lymantria dispar (gipsy moth). This agent has 

 also been employed by other workers [see this Revieio, Ser. A, i, p. 33 ; 

 ii, p. 101 ; iii, p. 549]. 



