518 



As flies and moths are known to be carriers of the mites, a natural 

 recommendation is the screening of all doors and windows in the cheese 

 rooms ; this precaution would also eliminate " skippers " from the 

 cheeses by preventing the ingress of cheese flies [Piophila casei]. 

 Injury is considerably lessened by brushing the cheeses daily to remove 

 the dust formed by the mites. 



Welsford (B. J.). Investigation of Bulb Rot of Narcissus. — Ann. 

 App. Biol., London, iv, nos. 1 & 2, September 1917, pp. 36-46, 



5 figs. 



Investigation into the cause of the disease known as bulb rot of 

 narcissus disclosed the fact that diseased bulbs were infested with 

 various pests, the chief being the mite, Rhizoglyphus echinopus, the 

 Syrphids, Eunierus strigaUis and Merodon equestris, and the Nematode, 

 Tylench'us devastatrix. The larvae of E. strigatus and M. equestris were 

 found to do considerable harm to narcissus plants, but the damage 

 done was quite distinct from the symptoms of bulb rot. R. echinopus 

 is common on unhealthy bulbs, but in no case w^as bulb rot obtained 

 by deliberate infestation with the mite. In all the diseased bulbs 

 dissected in the course of this investigation, the eelworm, T. devastatrix, 

 or its eggs, have been found. Fifty healthy bulbs infected artificially 

 with the eelworm and placed in sterilised soil developed the symptoms 

 cf bulb rot without any Fusarimn appearing. Various experiments 

 on these lines all led to the conclusion that T. devastatrix is the sole 

 cause of the disease [see also this Revieiv, Ser. A, v, p. 441]. Diseases 

 in hyacinths and onions have also been ascribed to this and other 

 eelw^orms. 



While the bulbs are in the ground, there is very little fear that the 

 eelworms will migrate to neighbouring weeds. As soon as the bulbs 

 are lifted, however, any eelworms remaining in the ground are likely 

 to migrate to suitable weeds, which would thus become valuable traps. 

 The question of migration and its extent would be well worth 

 investigation. A list of the more common British weeds and cultivated 

 plants that have been described as affording shelter to T. devastatrix 

 is given. Precautionary measures that will check its ravages to some 

 extent include care in selecting ground that has not been previously 

 infected with T. devastatrix, and, more particularly, has not borne a 

 crop of infested narcissus. It should be remembered in planting that 

 one diseased bulb vdW soon infect many others. Bulbs that do not 

 produce foliage at the proj)er time or that produce curved or crinkly 

 leaves should be dug up and burnt before they rot and liberate eelworms 

 in the soil. Dying leaves should be gathered and burnt before they 

 can fall on the soil and possibly infect it. Before replanting the ground, 

 all weeds should be removed and burnt ; they should never be allowed 

 to wilt on the soil nor be dug in. This is especially the case with weeds 

 growing in infested soil. 



Gray (K. A. H.). Notes on a Plague of Psocids in a Factory. — Ann. 

 App. Biol., London, iv, nos. 1 & 2, September 1917, pp. 47-49. 



Psocids, which feed as a rule on minute fungi and animal and 

 vegetable refuse, are only occasionally recorded as destructive to 

 corks, books, etc., that have been stored in damp surroundings. The 



