40 INSECT PESTS 



in the ground before the end of March, stimulating the 

 growth so as to resist attack, as it has been shown that 

 the flies are attracted first by the tender green shoots. 

 In fact they will lay their eggs on grasses if the corn 

 is too far advanced or is mown. There are a succession 

 of broods in the year, the last being in September, when 

 the flies are obhged to raise their last brood on wild 

 grasses. The symptoms of Frit Fly trouble are shown 

 by pale spots on the green leaves, which then become 

 reddened or withered, and there may be a stunting or 

 failure of the whole plant. In July, if the fly is estab- 

 lished, the summer brood will attack the grain itself, 

 particularly in northern latitudes where ripening is pro- 

 tracted. A badly infected crop must be ploughed in 

 deeply, choosing, by examination of the plants, the time 

 when the maggots are mostly half-grown, as this will 

 cut off the whole generation when there is no chance 

 of its continuance. 



Our next example is the Ribbon-footed Corn Fly or 

 Gout Fly (Chlorops tceiiiopus), which is very injurious 

 in some seasons to wheat and barley. The insect appears 

 in May and June, laying eggs on the spathes or sheath of 

 the young ear. The maggot then passes down the stem 

 below the ear and feeds at the base of the first joint, 

 changing to a brown, cylindrical pupa in July, the second 

 brood of flies appearing within a month. This brood 

 passes the winter within the corn plants, to hatch out 

 the following spring. The treatment consists of winter 

 or early spring sowing, as in the last instance, and keeping 

 down couch grass, which is an alternative food plant. In 

 addition, all refuse from an infected field should at 

 threshing time be burnt, and it is also advisable to 

 remove the next crop as far as possible from the site 

 occupied by the present one. The Ribbon -footed Corn 

 Fly has a natural enemy in the shape of a pretty little 

 ichneumon fly named Ccdinius niger. This diminutive, 

 dainty insect is about J inch long with flowing antennae 



