104 First Report oii Ecoiioinic Zoology. 



especially where as in grass land we have absolutely no means of 

 controlling them. The extra cost of night work would be amply 

 repaid. It is recorded by Miss Ormerod " that the grubs may be 

 collected by a top dressing of rape-cake and the roller passed over 

 the ground in the morning with good results " ; this does not always 

 seem to have the desired effect, however. 



Traps may be employed in gardens in the form of heaps of turf, 

 partly buried in the soil ; the flies lay their eggs there and the larvae 

 seem to be attracted to it and can then be collected and killed. 

 Eotting turf-manure and leaf-mould heaps should be kept free from 

 surface weeds and top dressed with gas lime, or else they will form 

 breeding grounds for these Tipulidte, and the larvae will be carried 

 to field and garden, and so contaminate the soil. Grass-borders in 

 gardens are favourite breeding grounds, and from these the larvae 

 spread to the bedding plants. In garden borders and beds they can 

 be easily destroyed by injecting bisulphide of carbon into the soil at 

 the rate of half an ounce to every square yard. This should be done 

 in late autumn or early spring. When crops are attacked various 

 stimulating manures should be employed ; they do not kill the larvae, 

 but they hasten on the growth of the plant and repair some of the 

 damage that the grubs have done. Nitrate of soda has the greatest 

 effect upon leather-jackets, but is not permanent in its action. It, 

 however, causes a cachectic condition in these pests, from which they 

 do not recover for some days, if its application at the rate of 2^ cwt. to 

 the acre is followed by rain. Miss Ormerod records an experiment 

 in wliich at the rate of 2 cwt. to the acre they had not recovered 

 from its ill effects after eight days. The effect of this artificial 

 manure on insects is so extremely variable that one must not rely on 

 it too much. At the same time it must be borne in mind that if it 

 has not the desired effect on the grub, it is still of value as a 

 stimulant to the plant. Hand and horse hoeing have also been 

 recommended and largely followed, but the good done is scarcely 

 sufficient for the outlay. 



