QUESTION DRAWER. 



Experiment Station Bulletin, concerning 

 the habits of this insect, and the best 

 methods of destroying it. 



Its life history is briefly as follows : — 

 The eggs (Fig. 1103, a natural size and 



Fig. 1103. — a, eggs of onion maggot, natural 

 size ; 6, eggs enlarged ; c, larva of natural size ; 

 rf, larva enlarged ; f, puparium of natural size : 

 /, puparium enlarged 



/' enlarged) which are laid on the leaves 

 near the ground, are white, smooth, 

 somewhat oval in outline and about one 

 twenty-fifth of an inch long. Usually 

 not more than half a dozen are laid on 

 a single plant, and they hatch in about 

 a week from the time they are laid. 

 The young larva, as soon as hatched, 

 burrows downward within the sheath, 

 leaving a streak of a pale green color to 

 indicate its path, and making its way 

 into the root (Fig. 

 1 104) devours all 

 except the outer 

 skin. When the bulb 

 of the plant has be- 

 gun to form, several 

 of the larva may be 

 found feeding in 

 company in it, and 

 after it has been con- 

 sumed they desert it 

 for another, ;ind still 

 Pio. 1 104. — .Show- others in succession, 

 ing the eggs and the yhe larvre reach full 

 larva at work on the 

 onion plant. growth in about two 



weeks, when they appear as shown in 

 Fig. 1 103, <:, natural size, d, enlarged. 

 The smaller end, which is the head, is 

 armed with a pair of black, hook like 

 jaws. The opposite end is cut off ob- 



licjucly, and there is a pair of small, 

 brown tubercles near the middle, and 

 eight tooth-like projections around the 

 edge. 



The larva usually leaves the onion 

 and transforms to pupte in the ground 

 outside. The puparium is shown of the 

 natural size at e and enlarged at f. It 

 does not differ very much in form from 

 the larva, but the skin has hardened 

 and changed to a chestnut brown color, 

 within which the true pupa is contained. 

 They remain in the pupa state about 

 two weeks in the summer, when the 

 perfect flies (Fig. 1105) emerge; after 

 pairing, the female deposits her eggs 

 for another generation. The winter is 

 passed in the pupa state, and the flies 

 emerge in the early part of June, or 

 about the time the young onions are 

 sufficiently grown to furnish food for 

 the young maggots. 



The following preventives and reme- 

 dies have been suggested : — 



Instead of sowing onion seed in rows, 

 where the young seedlings grow in con- 

 tact, or nearly so, giving every facility 

 for passing from one to another, they 

 should be grown in hills, so that the 

 larvje cannot make their way from one 

 hill to the other. 



Scattering dry unleached wood ashes 

 over the beds as soon as the plants are 

 up, while they are yet wet with dew, 

 and continuing this as often as once a 

 week through the month of June, is 

 said to prevent the deposit of eggs on 

 the plants. 



Planting the onions in a new place as 

 remote as possible from where they 

 were grown the previous year, has been 

 found useful, as the flies are not sup- 

 posed to migrate very far. 



Pulverized gas-lime scattered along 

 between the rows has been found useful 

 in keeping the flies away. 



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