484 Bulletin 78. 



present century into the United States and Canada where it now 

 occurs in nearly every State and Province in sufficient numbers 

 to annually destroy thousands of acres of Cabbages, Cauliflowers, 

 Radishes, and Turnips, thus causing a loss of thousands of dol- 

 lars every year to the gardeners of America. 



ITS FOOD-PLANTS. 



The name Cabbage Root Maggot, by which this pest is most 

 commonly known, would indicate that its food-plant was the 

 cabbage, B?'assica oleracea; this species now embraces the kales 

 or borecoles, coUards, brussel's sprouts, cauliflower, and broccoli. 

 However, we find that the insect has quite a range of food-plants, 

 but apparently confines itself chiefly to the Cruciferae or Mustard 

 Family. 



When it was described in 1833, it was said to live in the roots and stems of 

 the different kinds of cabbages ; the next year the same author described it, 

 under another name, as living in radishes, Raphanus sativus. More recently 

 Taschenberg and Schmidt-Gobel have added the following food-plants of the 

 insect in Germany : Raphamis radiola, turnips, and stocks iJMatthiola). In 

 England, the pest has been recorded, not always under the same name, how- 

 ever, on cabbage, including the other forms of this species, on turnips {B. 

 rapa), and on swede turnips {B. campestris). Miss Ormerod says that Mr, 

 Meade reared the insect in 1882 " from maggots found in earth round partly- 

 decayed Clover roots."* The same author believes that the maggots feed on 

 the stable manure used on cabbage fields. However, no definite observations 

 are given in support of this opinion. In 1833, Bouche said : " Avoiding the 

 use of new dung is likewise of no avail as these root- devouring larvae are not 

 annoyed by the want of it ; nor are they conveyed in it into the field, as 

 some believe. ' ' There is but little doubt that where large quantities of stable 

 manure are used the pest sometimes appears in the greatest nutnbers. 

 Possibly the smell of the manure may attract the insect, and certainly the 

 stable manure would lighten up heavy soils, thus enabling the maggots to 

 work to a better advantage and do more damage ; these seem the more prob- 

 able explanations of the presence of the pest in increased numbers where 

 stable manure is used, and not because the manure furnishes a further supply 

 of food for the maggots. 



*I find no reference to this in Mr. Meade's writings. Perhaps some roots of a Cruciferous 

 weed were overlooked among the Clover roots ; these, as will be shown later, would 

 account for the presence of the in.sect. This is an important point in the habits of this 

 pest and should be further investigated. 



