196 On the Insects affecting the Turnip Crop. 



careful investigations of Mr. H. Le Keux* that we were first made 

 acquainted with the actual economy of this little beetle. 



If the spring be warm the sexes pair from April to September, 

 during which period the eggs are deposited by the female on the 

 underside of the rough leaves of the turnips. She lays apparently 

 about one egg daily ; and ten pairs laid in a week only forty-three 

 eggs. This indeed was under confinement; but the correct- 

 ness of this estimate is supported by the fact, that in leaves taken 

 from the field, containing as many as six larvae, they were all of 

 different sizes^ indicating a variety of ages. The eggs are very 

 minute, oval, smooth, and partaking of the colour of the leaf. 

 See fig. 1. They are hatched in ten days; and the little maggots 

 immediately begin to eat through the lower skin of the leaf, and 

 to form winding burrows by feeding on the pulp. These bur- 

 rows are visible enough to the naked eye when the larvae leave 

 them, and the cuticles are withered and discoloured ; but in their 

 early stage they are discovered with difficulty : indeed it is only 

 by holding the leaf up to the light that they can be well detected. 



The larvcjo are pale, fleshy, and cylindrical, with six pectoral 

 feet, and a proleg at the apex : the head is furnished with jaws 

 and large dark eyes ; and the first and last segments bear dark 

 patches (fig. 2) : they are full fed in about sixteen days, when 

 they desert their burrov/s and bury themselves not quite two 

 inches below the surface of the earth, selecting a spot near to the 

 bulb;, where the turnip-leaves protect them from wet and drought. 



In the earth they become immoveable chrysalides (fig. 3)^ which 

 are brought to maturity, I believe^ in about a fortnight, when the 

 beetle or fly, as it is called, emerges from its tomb, again to fulfil 

 the laws of nature. 



The beetles (figs. 4 and 5) are shining black, minutely punc- 

 tured ; the head is rather small, with two prominent orbicular 

 eyes, finely granulated ; the mouth projects a little, the upper lip 

 and feelers being visible: just above the nose are placed. two 

 longish horns, each composed of eleven joints, the three next the 

 head ochre-coloured, the first being the longest, the remainder 

 dull black, the terminal one pointed : the thorax, or trunk, is 

 broader than the head, narrowed a little before, with the sides 

 rounded : the two wing-cases are moveable, and form an oval ; 

 they are twice as broad as the trunk, and four times as long ; each 

 has a distinct ochre-coloured stripe, sometimes approaching to 

 white, running down the centre, generally winding a little on the 

 outside, near the middle, and curved inward at the extremity : 

 beneath are ample wings, twice as long as the body, and folded up 



* Transactions of the Entomological Society of London, vol. ii. p. 24. 



