262 ECONOMIC ENTOMOLOGY 



Control. — Summer-fallow grass lands; prevent volunteer growth 

 in autumn. 



PSILIDiE (RUST FLIES) 



Carrot Rust Fly {Psila roscB Fab.).- — This fly is a native of Europe, 

 and the larva frequently does considerable injury to the roots of 

 carrots, celery and parsnips. 



Adult. — One-sixth inch long, dark green, sparsely clothed with yellow 

 hairs; eyes black, and head and legs pale yellow. 



Eggs. — Deposited by female about roots of host through cracks 

 in the ground. 



Larva. — Maggot dark brown, ^fo inch long, slender, truncate 

 at posterior end; segments well marked, head small. 



Pupa. — Puparium dark brown; anterior segment obHquely trun- 

 cate; \i, inch long; pupation in the earth. 



Life-history. — (Consult Fletcher's Reports and Bull. 2>Zy U. S. Div. 

 Ent.) Winters as larva or pupa; adults appear early in the season; 

 summer generations develop in 3 or 4 weeks (Curtis); both flies 

 and maggots found throughout the warmer months; number of broods 

 uncertain. 



Control. — Spray the carrots four or five times at intervals of a week 

 or ten days with kerosene emulsion, the first application at the time 

 of thmning; spread the earth in which carrots have been stored in the 

 poultry yard; sow late and practice rotation of crops. 



AGROMYZID^ (LEAF MINER FLIES) 



Marguerite Fly {Phytomyza chrysanthemi Kowz.). — (Mass. Agricul- 

 tural Experiment Station, Bull. 157.) Attacks compositous plants 

 and is especially injurious in the greenhouse. Occurs in the Northern 

 States, and has done considerable injury in B. C. 



Adult. — A small greyish fly }{2 inch long, with a yellow stripe on 

 each side of abdomen; face yellow; antennae black; legs black with 

 yellow markings; rather inactive. Average length of generation about 

 ;^T, days; several generations a season in greenhouse. 



Eggs. — ^Laid singly in incisions between flesh and skin of leaf. 

 Hatch in 5 days. 



Larva. — Burrows in the leaf, producing irregular whitish lines or 



