THE PEA LEAF MIXER. 45 



PREVENTIVE MEASURES. 



The only measures that can be taken are those of a preventive 

 nature. 



As in the case of the Frit Fly, early sown crops are less' liable to 

 attack than late ones. Miss Ormerod (I) reports that a correspondent 

 informed her that of a field of barley infested by this fly : " The field 

 was sown in three patches, as the preceding crop of Swedes was fed 

 off. The first patch was sown in March, and is practically free from 

 injury. The second part was sown on April 6th, and is affected to the 

 extent of about 2 per cent. The third part was sown on May 3rd, and 

 has suffered to the extent of not less than 20 per cent." 



All wild grasses should be kept down. 



Autumn and Winter sown crops should not be put close to fields 

 that have been previously infected. 



THE PEA LEAF MINER. 



Phytoinyza pisi, Kalt. 



Early in July, a Worcestershire correspondent forwarded a bundle 

 of peashoots attacked by the larvae of this small dipterous fly, \vhich 

 had caused considerable damage. 



The larvae had worked from the edges of the leaves towards the 

 point of attachment to the stem. In some cases they had continued 

 to mine into the stem itself, tunnelling down for some distance. 



The larvae are greyish-white in colour and, when full-fed, about 3.5 

 millim. in length. In the leaves where the mining had just commenced 

 they pupated in 32 days. Most of the larvae desert the leaves and 

 stems and pupate in the soil ; but a few r were noticed in the leaves ; 

 and the flies were bred out from these. 



In all probability the flies which hatch out in the early spring 

 from the pupae mentioned above, attack wild lathyri, and it is the 

 second brood that attacks the cultivated variety. 



The most effective method of dealing with this pest, which, given 

 favourable conditions, might become a very serious one, is to burn the 

 haulm before the larvae pupate. Failing this the ground should be 

 dressed with Apterite sometime during the winter. 



THE ORCHID MIDGE. 



Isosoina orch idea nun, J.O.W. 



Orchids damaged by this tiny fly have been received from a 

 Worcestershire correspondent. 



The opinion held by many horticulturists is that this fly is intro- 

 duced with imported plants, Cattleya mendeli being one of the worst 



(i) Man. Inj. Insects, 1890, p 77. 



