TURNIP AND CABBAGE ROOT-GALL WEEVIL. 



145 



commonly confused with the malformations known as " Finger-and- 

 Toe," &c. ; that of the Turnip and Cabbage Eoot-gall Weevil, with the 

 knobs and lumps that it causes on the roots, is perhaps the attack 

 least easily distinguishable from the lumpy deformities caused by the 

 Slime Fungus. 



This attack is caused by a small blackish weevil beetle, of shape 

 and size figured at p. 144, furnished with a long curved snout, to the 

 sides of which are affixed a pair of " elbowed " horns or antennae ; the 

 thorax, or fore body, has a channel running lengthwise along the 

 centre, and the wing-cases have very fine furrows running along them. 

 The beetles have a slight sprinkling of whitish or grey scales above, 

 and beneath are light coloured from the greater amount of these scales. 



The female lays her eggs either on the sur- 

 face of the attacked roots, or in a little hole 

 which she forms for their reception, and the 

 maggots which hatch from these establish 

 themselves in the outer part of the Turnip 

 bulb, and in the case of Cabbage plants for 

 the most part in the main root, or rather 

 underground stem. There the presence of 

 these maggots causes the growth of the galls, 

 within which they may soon be found, even 

 without the help of a magnifying-glass. They 

 are (when seen magnified) whitish grubs, very 

 much wrinkled across, fat and fleshy, and with 

 a yellowish or chestnut head, armed with strong, 

 toothed jaws, these also chestnut-coloured, and 

 darker at the tips. These maggots are legless, 

 commonly lie curled on one side, as figured at 

 p. 144, and I have noticed that they varied in 

 colour with their food, being of an orange 

 colour when feeding on Swedes. When full-fed 

 they leave the galls, and make little earth 

 cocoons in which they turn to chrysalids, and 

 thence to weevil beetles. But the main point 

 here is to give the distinctions by which the 

 insect-galled roots may be known from those 

 that are fungous-diseased. One point is the 

 regularity of the formations, as shown in the 

 figure. The galls are commonly rounded 

 smooth knobs, single or in groups, as shown, and on cutting them 

 open, we do not find, as in Finger-and-Toe, or Club, a mere mass of 

 disorganised tissue progressing to general rottenness, but we find, as 

 figured at p. 144, a central chamber bearing signs of having been 



L 



Young Eape plant with 

 galls of C. sulcicollis, after 

 Dr. Eitzema Bos. 



