THE INSECT WORLD. 



363 



to reach the maggots just when they are hatching, and becomes 

 effective for that reason. Apphed later, when the insects have 

 already made their way into the radishes, it would be useless. 

 Here the farmer must necessarily make a few observations of his 

 own to determine the proper time for applying the fertilizer 

 remedy, and this is not difficult. The flies lay the eggs in little 

 masses on the surface of the ground near to the infested plants. 

 They are white, slender, and cyHndrical, nearly one-sixteenth of 

 an inch in length, and quite visible on close examination. When 

 these eggs are found generally distributed over the fields the 

 time to make the insecticide apphcation has arrived, because they 

 hatch only a few days after they are laid, and the young larvae 

 must be reached then or not at all. The carbolic acid emulsion 

 diluted thirty-five times may also be applied with good prospects 

 of success in killing the maggots, or the ground tobacco may be 

 used over the rows just as soon as the plants are up. 



The onion-maggot, Phoi^bia ceparum^ is, perhaps, next in im- 

 portance, and its habits are essentially the same as those given 

 for the cabbage-maggot, — that is, the eggs are laid by the fly 

 quite early in spring, 

 next the onion stems or 

 leaves at the surface of 

 the ground, and prefer- 

 ably in young onion 

 beds. In the latitude of 

 New Jersey this occurs 

 in May, but the date va- 

 ries somewhat accord- 

 ing to the season and to 

 the time at which these 

 plants are started. The 

 larvae work their way 

 into the bulb at once 

 and begin their scraping 

 and gnawing, leading to 

 the rapid decay and death of the plant. Matters are even more 

 serious here than in the cabbage, because where a bulb has been 

 started in decay, it usually continues, even if the maggots are de- 

 stroyed, and in the case of sculHons, they become unmarketable. 



Fig. 420. 



The onion-maggot. — Larva, pupa, adult, and section 

 of an infested onion. 



