120 



BEETLES. 



much in old Mustard straw ; this straw, therefore, 

 should be destroyed ; also the old reeds by ditches, 

 where it harbours, and the ditch-growing plants, such 

 as Brooklime and others, on which it feeds in spring, 

 should not be allowed to get numerous. Sowing as 

 early as possible, and sowing Brown instead of White 

 Mustard, because it comes earliest of the two, and 

 thus avoiding the special season of attack, are found to 

 answer ; and also a vigorous growth, such as will not 

 go down at once before attack, is of great use. But, 

 in the case of this plant, which is grown to a great 

 extent in special districts, one great means of preven- 

 tion is more frequent change of crop. 



FiQ. 'J3.— Ladybirds : chrysalis, egg, and grub, nat. size and mag. 



This point of rotation of crop as a means of insect 

 prevention will be alluded to presently. 



The remaining division of Beetles is the section of 

 the Trimcra (or Pscudo-trimera) , which includes those 

 which have apparently only three joints to their tarsi. 

 " They are, however, really composed of four joints, 

 the second, which is bilobed, receiving the very minute 

 third, and the base of the apical joint."— E. C. Rye. 



The most important family in this section is that of 

 the Coccinelluhe, which includes the well-known Lady- 

 bird Beetles, ligured above. The common red and 

 black-spotted kinds of these Beetles are very familiar. 



