4- THE CABBAGE MAGGOT. 



OBSERVATIONS ON ITS LIFE HISTORY. 



Notes on the Occurrence of the Fly. First observed as 

 early as May 9th, more nninerous May nth, but no egg- 

 observed on this date. Specimens emerged in breeding jars 

 in laboratory as late as September 26th. 



The Egg and Egg Laying. Eggs were found abundantly 

 on May i6th, both on cabbage and cauliflower, 75 per cent 

 of the cabbage examined being infested, some cabbages having 

 as many as ten eggs to the plant. Of cauliflower plants 

 examined on this date, over 90 per cent were infested ; the 

 largest number of eggs found on a single plant being twenty- 

 two. This indicates emphatically their preference for cauli- 

 flower. 



The action of the fly in ovipositing was repeatedly 

 observed by members of this department, and the observa- 

 tions coincide so closely that I give here almost verbatim the 

 report of an assistant whom I had put to work on this 

 problem. Naturally every fly will not act in exactly the same 

 way, but his account will serve to show in general the actions 

 of the female at that time. 



"When a fly lights on a plant in search of a place to deposit 

 her eggs she runs quickly down the stalk to the ground. 

 Here she seaixhes alternately with her forward and rear end 

 or ovipositor for some crevice or crack through 

 which she can obtain access to the stalk of the 

 plant under ground. She acts rather nervous- 

 ly, occasionally running up on to the leaves. 

 The ovipositor is, when extended, nearly as 

 long as the abdomen, very flexible and pointed. 

 With this she tries every place offering any 

 chance of furnishing what she desires. When 

 she has finally found a crevice she forces the 

 ovipositor in to the limit and stands still for 

 ^'bage^'lnf^^ot^ *^fl^ se\eral seconds, meanwhile usually polishing 

 much enlarged. (Au- h^y head witli her forc pair of legs. Then 



thor s illustration.) • i i i • • ■, r ?• i • 



Withdraws her ovipositor, and after climbing on 

 to the plant again, flies with a slow flight near the ground to 

 a point of vantage or to another plant. I watched five flies 

 at work, and they all laid eggs while I was watching them. 



