92 MUSTAED. 



wood or bark, and are especially noted as fond of sheltering amongst 

 the reeds and rushes, by ditches and drains, in fact, in any available 

 shelter. 



And to places of winter shelter from which the beetles are brought 

 into connection with the coming crop in the spring must be added, 

 what amount of Mustard Beetles may be in the Mustard seed ; a 

 matter to which attention has been more directed within the last few 

 years than was formerly considered necessary. 



From these winter quarters the beetles come out in spring and 

 spread to any food-plant near, especially those (like Mustard) of the 

 cruciferous flowered kind, as the Water Cress, the Common Bitter 

 Cress, Charlock, Turnip, Cabbage, &c., and though of a different order, 

 the Brook Lime, is also one of their food-plants. 



These various plants serve the beetles for a place for their egg- 

 laying until the Mustard is ready, consequently to clear what may be 

 called the nurseries of the year's attack, as well as to prevent, so far as 

 may be reasonably possible winter shelters being left for the parent 

 beetles, are respectively methods of lessening coming attack. 



On these food-plants, wild or cultivated, the beetles which have 

 lived through the winter lay their small eggs, and then they die. The 

 grubs feed voraciously, until they are full-grown, when they go down 

 into the ground to turn to chrysiilids. From these the summer brood 

 of beetles come out, it may be in about a fortnight, more or less, and 

 these start new attack, and thus the infestation goes on. It may con- 

 tinue till quite late in the autumn, as noted in the following observation 

 sent me on Oct. 5th, from Preston, Hull, by Mr. H. L. Leonard, with 

 specimens of the Phadon hetula accompanying : — 



"I stated in my letter that a very heavy rain had apparently 

 destroyed the Mustard Beetle, as none could be found a fortnight after 

 it. I am sorry to say they have reappeared on some of the farms in 

 large numbers during the past ten days. I enclose specimens." — (H. 

 L. L.) 



Where this appearance of successive generations of the insects 

 thus alternating in grub and beetle state, is not well known, it is very 

 important practically that it should be thoroughly understood. It is 

 often thought that when the grubs disappear the danger is past, but 

 this is not at all the case. The disappearance of the grubs is (in 

 natural course) only the forerunner of their reappearance in beetle 

 form to over-run the plants once more, or migrate in legions (if they 

 do not find sufficient food) to other pasturage. 



Prevention and Eemedies. — When the beetles are on the young 

 plants, rolling has been tried, but even rolling with the " Crosskill," 

 so far as reported, has been of little use. Hoeing has been considered 



