316 INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



reached in from three to twelve days. Pupation takes place in an 

 enlargement at the end of the mine, usually near the under surface of 

 the leaves, beneath litter on the surface or just below the surface of 

 the ground. In California pupation takes place almost entirely within 

 the mines in the leaves. During the summer the pupal stage requires 

 from one to two weeks, with an average of about ten days. The adults 

 emerge by cutting a slit through the epidermis of the leaf. The life 

 cycle during the summer averages about twenty-three days, and from 

 one to one and one half months in late autumn. There are from three 

 to five generations a year. 



Nature of Work. — The small egg-punctures may be observed on the 

 under surface of the leaves. Prom these the small mines are made just 

 beneath the upper epidermis. The mines are easily traced by the dis- 

 colored tissues just above them. They may be short or long and wind- 

 ing enough to completely sever the epidermis and cause it to appear 

 white and dead. The plants may thus be greatly weakened and the 

 whole field may appear exceedingly unhealthy. Usually, however, the 

 damage is confined to single plants or to small areas. 



Distribution. — Webster and Parks 251 report the species from San 

 Francisco, Los Angeles and Imperial counties. On May 5, 1914, Mr. 

 Leroy Ohilds collected the larva' mines at Redding, Shasta County. 

 From these adults were subsequently reared. The insect probably has 

 a wide range over the State. 



Food Plants.— in California the serpentine miner has been reared 

 from alfalfa in Imperial and Shasta counties, from cabbage and sugar 

 beets in Los Angeles County and spinach in San Francisco County. 251 

 Webster and Parks-' 5 -' also report the following other hosts from the 

 United States: garden beet, red clover, sweet clover, white clover, cot- 

 ton, cowpea, smooth rock-cress, fenugreek, common malva, hedge mus- 

 tard, nasturtium, sweet pea, pepper, plantain, potato, radish and rape. 

 The following additional plants are also reported from Europe by the 

 same authors: bellflower, zigzag clover, garden daisy, dandelion, Euro- 

 pean elder, hedge nettle, hemp nettle, henbane, rest-harrow, bladder 

 senna, cypress spurge and sow thistle. 



Control. — Clean culture and deep fall plowing have been recom- 

 mended for annual crops and frequent cuttings for such hay crops as 

 alfalfa and clover. For garden crops use the remedies recommended 

 for the chrysanthemum leaf-miner. 



THE ASPARAGUS MINER 

 Agromyza simplex L<bw 



(Fig. 344) 



Description. — The flies have a wing expanse of about £ inch and 

 are metallic-black in color. The maggots are 4, inch long and white. 

 The puparia are y inch long and red or brownish. 



Life History. — The first adults appear early in the sirring and begin 

 egg-laying. The larvae mine beneath the epidermis of the stalks near 

 the bases and may penetrate eight inches underground. The injury 



"'Jr. Agrcl. Reach. U. S. Dept. Agric, Vol, I, No. 1., pp. 62-63, 1913. 

 ="Jr. Agrcl. Resch. U. S. Dept. Agric., Vol. I, No. 1, pp. 63-64, 1913. 



