INSECTS INJURIOUS TO BEETS AND SPINACH 345 



which will prevent various fungous diseases, and with which 

 Paris green can be used much stronger without danger of burn- 

 ing the foliage; or it may be applied dry by mixing with from 

 ten to twenty parts of flour or plaster, dusting it on in early 

 morning, while the dew is still on the plants. Arsenate of 

 lead sprayed at the rate of 3 pounds to 50 gallons, or used as 

 a dust, will be equally effective, will adhere to the foliage better, 

 and will be less likely to burn the foliage. 



The Beet or Spinach Leaf -miner.* 



Frequently beet and spinach leaves will be found with tor- 

 tuous mines or large blotches which have been mined out by 

 small white maggots beneath the surface epidermis. This injury 

 is most commonly due to the maggot of a small fly shown in 

 Fig. 248. "The ground color is gray with the front of the head 

 silver white. The body, including the legs, is somewhat sparsely 

 covered with rather long stiff black hairs. When in action the 

 body is usually carried in a somewhat curved position, but when 

 extended measures nearly a quarter of an inch. The maggot 

 (/) is white, and so nearly transparent that the contents of the 

 abdomen can be seen through the posterior portion." 



Life History. " The flies, by close observation, may be seen 

 in flight just above the ground or hovering about their different 

 food plants. The eggs are placed on the lower surface of the 

 leaves and arranged in masses of from two to five. When the 

 young hatch they bury themselves within the leaf tissue, con- 

 structing a thread-like mine which they afterwards extend in a 

 curve or semicircle. Transformation to pupae takes place in 

 most cases in loose soil, which the maggots enter to only a short 

 distance, or under fallen leaves. Occasionally maggots trans- 

 form within a leaf if the latter happens to rest on the ground. 

 Dr. Howard states that the eggs hatch in from three to four 

 days, and the larval stage is passed in seven or eight days, the 

 puparium or resting stage requiring from ten to twenty days. 



* Pegomyia vicina Lintn. See Chittenden, I.e., from which the quota- 

 tions are taken. 



