CONTROL OF GARDEN DISEASES AND INSECTS. 51 



attack by the same insects, but comparatively few species injure 

 onions as a rule, the onion tlirips (see p. 19) and onion maggot 

 causing the greatest damage. 



i 



ONION TIIEIPS. 



The onion thrips is a general jx'st and is considered on page 10. 



THE ONIOX maggot/ 



Injury due to the onion maggot is the most important drawback 

 to the culture of onions. It is accomplished by the consumption of 

 the bulb, inducing subsequent decay of the affected portions and 

 their very frequent destruction. 



The fly and the minute maggot resemble the seed-corn maggot 

 (fig. 57, p. 52), although averaging a little larger. The male is 

 gray, with black bristles and hairs ; it has a white face with black 

 hairs, and there are three dark lines on the body between the wings 

 and a row of black spots on the abdomen. The female is a little 

 larger, inclined to dark yellowish, and has a pale yellowish face. 



As in the case of the cabbage maggot, this is a northern form, and 

 two or three generations evidently are the rule. 



Control. — The methods advised for the seed-corn maggot (p. 28) 

 frequently are about all that are necessary for this species. The 

 tarred pads can not be conveniently or economically used on onion. 

 The flies are probably attracted to old onion beds and to crop 

 remnants; hence, clean field methods are always advisable. One of 

 the best remedies is carbolic-acid emulsion (p. 8), but the best 

 one known is a poisoned bait to attract and kill the flies. This bait 

 is made as follows : 



Sodium arsenate ounce— i 



Water ^ gallon 1 



"Cheap molasses pint__ ' 1 



Dissolve the arsenate of sodium in boiling water and then add 

 the molasses. This bait has proved to be cheap, attractive, and 

 effective. Since it is not necessary to cover the foliage, the bait 

 may be applied in large scattering drops. An ordinary syringe, or 

 a whisk broom dipped into a bucket of the solution and shaken 

 about on each side of the operator, will apply the bait satisfactorily. 

 This poisons the flies as they are attracted to the fields. Perfect 

 stands of onions have been secured by this method — some of the 

 best that have been secured for many years. 



OTHER ONION INSECTS. 



More often than not the onion maggot is accompanied by the seed- 

 corn maggot (fig. 57), which has also been called the bean fly. Some 



^ Pcgomiia cepetorum Meado. 



