268 LEAF-MINING INSECTS 



two or three generations during the summer. The last 

 generation emerges during September and October and these 

 adults apparently hibernate. 



EPHYDRIDAE 



The flies of this family frequent moist or aquatic locations. 

 They are blackish or metallic in color with widly separated 

 eyes and few bristles upon the head. Their close relation- 

 ship with the Agromyzidae and the Drosophilidae has al- 

 ready been pointed out. 



The larvae live in wet situations, many inhabiting salt 

 water or even brine. Some have been found feeding in the 

 sap of trees, others boring in the stems of plants and the 

 species of the genera Hydrellia and Notiphila mine the leaves 

 of plants. The food plants listed by Frost (1923) would 

 indicate that grasses formed their favorite host plants but 

 the recent work of Hering (1925) shows that many aquatic 

 plants of the European genera Alisma, Hydrocharis, Buto- 

 mus and Stratiotes are mined by the larvae of Hydrellia. 

 Some of these plants float upon the water like duck-weed 

 (Lemna). 



Our knowledge of the life-histories of these species is 

 brief. Apparently all the species of these two genera trans- 

 form within their mines. Some produce linear mines while 

 others make blotch mines. 



Hydrellia 



At least eleven leaf-mining species have been described 

 from Europe. A North American species, Hydrellia scapu- 

 laris described by Loew (1862) has been recorded as a leaf 

 miner of Hordeum. In recent article De Ong (1922) states 

 that the larvae of this species often causes severe damage to 

 rice. He describes the habits of this species briefly. It 



