364 AN ECONOMIC ENTOMOLOGY. 



The maggots attain tlieir growth about the end of May or early 

 m June, and before the middle of that month a second brood of 

 flies may be found in the fields. This second brood is often 

 much the most injurious, and (juite frequently it attacks seedling 

 onions, ruining entire beds. The older plants, if they have 

 reached this date unharmed, are usually safe for the year. Exactly 

 how many broods there are has not been accurately ascertained, 

 and probably the number varies somewhat according to latitude. 

 We do know that the insects pass the winter partly in the pupa 

 stage in the ground, and partly as adults in barns, farm-houses, 

 and other sheltered localities. Many measures to prevent injury 

 have been proposed, none with any marked success, except those 

 here mentioned. The most promising is sand soaked in kerosene, 

 one cupful to a pail of dry sand, and placed at the base of the 

 onion plants along the rows. This prevents egg-laying by the 

 fly, kills any young larvae that may attempt to work through it, 

 and seems to have been quite satisfactory where tested ; but it is 

 obviously not a suitable measure for application on a large scale. 

 In New Jersey tons of onion seed and sets are raised annually, 

 and the following j^ractice has been found uniformly successful. 

 Keep a close watch for the first signs of maggots ; carefully lift 

 out and destroy all infested plants that have wilted down so far 

 that they cannot survive, and so kill the more advanced maggots. 

 Turn awav the earth from the rows with a hand-plough so as to 

 expose the root system in part, then apply broadcast about six 

 hundred pounds of kainit and two hundred pounds of nitrate of 

 soda per acre ; turn back the earth to the plants, and this will put 

 a period to the injury. The application is best made just before 

 or during a rain, or immediately after a shower that has wet 

 down pretty thoroughly. The object is to get the salty fertilizers 

 dissolved rapidly and brought into direct contact with the roots 

 of the plant, and, of course, with the insects as well. This 

 method has ]:)roved entirely satisfactory in New Jersey, and on 

 li^ht lands it will jjrobably act equally well in other localities ; 

 but it has never been tested on hea\'y land, and the action may 

 not be entirely the same. The application of the fertilizer has the 

 advantage of imparting additional vigor to the plant, and stimu- 

 lates it to ov^ercome such injury as may have been alrc'ady caused. 

 It is a good plan always and under any circumstances to care- 



