CHAPTER XIII 

 ONION INSECTS 



Onions are subject to attack by a relatively small number 

 of insects. The most important of these are the onion maggot 

 and the onion thrips, but occasionally cutworms and wire- 

 worms may cause serious loss. 



The Onion Maggot 

 Phorbia ceparum Meigen 



In Europe and America, onions are often severely injured 

 by the attacks of a small white maggot that feeds on the under- 

 ground stem or in the bulb. The maggots may attack and 

 destroy the plants soon after the seeds have germinated, and 

 the failure to obtain a stand is, therefore, often attributed to 

 poor seed. 



The flies appear in the onion fields in the spring and the 

 female deposits her smooth, white, elongate oval eggs, which 

 are slightly grooved on one side and about ^ inch in length, 

 in the base of the leaf-sheath, on the side of the stem near the 

 ground, and in cracks and crevices of the soil. The eggs hatch 

 in three to ten days and the young maggot works its way 

 down along the stem, usually within the sheath. If the plant 

 is very young, the maggot may so injure the stem that the 

 whole top dies. When the plants are older, the maggots bur- 

 row into the bulb and cause decay to develop. Several maggots 

 are often found in a single bulb. The full-grown maggot is 

 nearly J inch in length, smooth, and dull whitish in color. The 



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