4 First Report on Economic Zoology . 
scented vernal and annual meadow-grass ; it is also found in daisies, 
buttercups, and plantains. Teasels and hyacinths also harbour it, 
according to Bitzema Bos. It appears that barley and carrots are 
free from its attack. 
Part of their life is spent in the soil, and they can then be 
successfully treated as mentioned below. 
Prevention and Treatment. 
1. Deep ploughing in autumn ; the depth should be eighteen 
inches. By this treatment the layer of earth that contains the 
eel-worms is buried, and so they are put out of the way of the next 
crop. Ploughing at a less depth does good if a skim coulter is 
attached, but the deeper the land is ploughed the better. 
2. On eel-worm land avoid crops in rotation that are attacked, 
and use those that are not — i.e. barley. Clover after “ tulip-root ” 
must carefully be avoided. 
3. Sulphate of potash on a diseased field does good at about the 
rate of 1 cwt. to the acre. 
There is not the least doubt that by late autumnal deep ploughing, 
by judicious rotation, and by the use of certain artificial manures, 
the pest can be easily fought with success. It is also said that 
stable manure should be avoided. 
There was also a single puparium of the Frit Fly {Oscinis frit) 
found in one plant from this district. 
The Frit Fly on Oats. 
(' Oscinis frit , L.) 
Oat plants sent to the Board of Agriculture from the sewage farm 
of the Croydon Corporation were being destroyed by a small 
dipteron, which has done a great deal of damage to the oat and 
barley crops in the south of England. This small fly is the so-called 
Frit Fly, the Oscinis frit of Linnaeus, the Oscinis vastator of Curtis. 
The larvae of the Oscinis feed just inside the crown of the plant, 
and in the majority of cases destroy it ; but when they feed between 
the outer leaves, as they often seem to do, the crop may survive. 
Crops that look irreparably damaged often tiller out and produce 
a moderate yield. This year (1902) the pest has been very harm- 
ful. The flies were nearly all hatched out by June, but some sent 
in the sample of oat plants from Croydon were only just entering 
the pupal stage. The second brood probably lays its eggs on the 
