ROOT CROPS. 41 



autumn, it hibernates until the following spring. If, on 

 the other hand, it becomes a pupa during the sumvter, it 

 remains in this state from fourteen to twenty-one days, 

 when it becomes a perfect insect. The fly is nearly five- 

 eighths of an inch across the extended wings. The male 

 is grey in colour, with three dark bands on the abdomen ; 

 while the female is of a yellow colour. 



Prevention. — (1) Hotation of crops. (2) " The most 

 successful method of cultivation is to trench the ground 

 for the onions in the autumn, working plenty of manure 

 into the soil, or placing a good layer at the bottom of the 

 trench." (3) Raise all sickly-looking plants by means of 

 a spud. This will decrease the number of grubs, etc. 



Cure. — (1) Applications of paraffin oil mixed with 

 water (1 pint to 2 gals.) have been the means of destroy- 

 ing this pest. (2) Soap-suds have also been recommended 

 as a remedy. (3) Soot, sulphur, and lime are powerful 

 insecticides. 



The Putrefactive Microbe of Onions {Bacterium 

 aim, Fig. 16). It may be useful, in passing, to allude to 

 a microbe which is a destroyer of onions (ivhen stored), 

 by causing putrefactive changes to occur within the bulbs. 

 This putrefaction ultimately . gives rise to a greenish- 

 coloured slime over the surface of the decomposing 

 onions. This microscopic organism must therefore be 

 looked upon as an enemy of the farmer, market-gardener, 

 and others. 



The author discovered this microbe upon onions kept in 

 a warm, damp, and dark place. The cells are each about 

 0-005 to 0-007 millimetre long, and about 0-0025 milli- 

 metre 1 wide. The organism has been called Bacterium 



1 1 miUimetre = 0-03937 inch. 



