1909.] Insect, Fungus, and other Pests. 



841 



be understood that the large number of possible host plants 

 greatly increases the difficulty of combating the pests. 



There are no records of the mites living in the soil during 

 the winter apart from food plants, but it is not im- 

 possible that this is occasionally the case. There is a stage 

 in the life-history, though it does not occur in the develop- 

 ment of every individual, known as the hypopus stage, which 

 is a protective condition in which the mite can endure ex- 

 tremes of temperature and of drought which would be fatal 

 to it in any of its active stages. In this stage advantage is 

 taken of passing animals to which the hypopus fixes itself and 

 is so distributed. 



Generally speaking, infected soil should not be used, at 

 any rate without sterilisation ; and on a large scale sterilisa- 

 tion or disinfection of the soil would be too expensive, even 

 if practicable. On a small scale the soil might be baked or 

 disinfected with bisulphide of carbon. 



Practically nothing can be added to the treatment suggested 

 in the leaflet. Immersing the bulbs in a solution of liver of 

 sulphur (1 oz. to 1 gallon of water), when lifting them in July 

 would be fatal to all the mites that were external and came 

 within the reach of the mixture. Unfortunately, some of 

 the mites get well into the bulb, and are thus likely to escape 

 the treatment, and afterwards to become the founders of new 

 colonies. Treatment of the lifted bulbs with bisulphide of 

 carbon might give more successful results, as the fumes are 

 penetrating. 



A Carnivorous Worm. — In September the Board received 

 from Hampton-on-Thames some specimens of a flat worm 

 which, it was stated, were found in a greenhouse where there 

 was plenty of moisture, and in which the temperature was 

 never lower than 50 0 F., and often up to 8o° F. or 90 0 F. 



These worms were found on examination to be Bipalium 

 kewense (Mosely), a species which may measure up to nine 

 inches and over in length. B. kewense belongs to the 

 section of free-living flat worms known as Turbellaria, and 

 to the Order Tricladida. The Turbellaria are carnivorous in 

 diet. Bipalium kewense has been introduced to Britain with 

 plants or soil from the tropics. It was found first of all in 

 the plant houses at Kew Gardens, and has since been re- 



3 n 



