New York Agricultural Experiment Station. 



629 



As soon as the young maggot hatches from the egg it buries 

 itself within the leaf tissue. When they first begin to feed they 

 make quite a distinct thread-like " mine " but they soon feed, as Dr. 

 Lintner says : " In a curve of an entire semi-circle." The anterior 

 portion of the body is extensile and allows them to feed in this 

 manner. As soon as they begin to feed in the last-named manner 

 the mine appears as a blistered blotch. The blistered appearance 

 being caused by their devouring the green tissue or parenchyma of 

 the leaf. From three to four larvfe are often found in one blistered 

 portion of the leaf. When feeding on ChenopocUum one leaf does 

 not furnish enough food for one maggot, so they ha^'e to migrate to 

 other leaves. This same habit holds when they feed on spinach, at 

 least while the spinach is small or in case they attack the seed leaves. 

 In spinach which is gathered for market they seem to have n)ore of 

 a tendency to migrate and find the greenest leaves. This habit 

 prevents the sharpest-eyed house-wife finding them all, when pre- 

 paring the sphiach for "greens," for it is impossible to detect their 

 presence within the leaf tissue until after they have eaten a portion 

 of the parenchyma. 



Occasionally the maggot changes to the pupa within the leaf 

 especially if the latter lies on the ground and is decaying. The 

 majority of them enter the loose soil a short distance or crawl under 

 the fallen leaves to pupate. 



Food Plants. — As far as known the beet, spinach and Cheno- 

 podium are the only plants on which this maggot works. Where 

 all three of these plants are raised in such abundance as they are 

 liable to be in gardening districts the flies are sure to find plenty of 

 food plants to deposit their eggs upon. Where chenopodium is not 

 disturbed by cultivation it matures about October 1st ; hence the 

 principal food plant during the fall is spinach. 



There is a possibility of their feeding on the leaves of some of the 

 " docks " or " sorrels." 



Description. — The eggs are white, about .03 of an inch in 

 length, delicately reticulated and nearly cylindrical in shape. The 

 white reticulated portion of the egg is an outer covering and is 

 easily removed in little scale-like particles. When the eggs are 

 deposited this covering is apparently viscid and aids in attaching 



