56 
MUSTARD. 
“it is curious to see in a field of Kohl Rabi (which it is the custom to 
grow here in the same field alternately with Mangel Wurzel), how 
completely they avoid the latter.” 
In 1882, Mr. Caswell, of Peterborough, wrote to me* regarding a 
great pest in the shape of a beetle, called by the farmer the “ Black 
Jack,” that infests the Fen district between Peterborough and Ely, 
especially round Whittlesea. They feed upon White and Brown 
Mustard plants, Cress, Rape, and Cole, and are so destructive that in 
six or seven days they will completely destroy a field of twelve acres, 
and leave nothing but the bare stalks. Mr. William C. Little, of 
Stag’s Holt, March, also writing to me on the same subject,! mentioned 
“that for some years past immense damage has been done by the 
Mustard Beetle to crops of White and Brown Mustard.” 
In the present year, in a leading article on Foulness Island, in the 
‘ Agricultural Gazette ’ of Oct. 5th, pp. 825, 326, it is mentioned :— 
“ The only paying crop at present is Mustard, which, after a year’s 
fallow and plenty of London dung, is not only productive itself, but 
the best possible preparation for the Wheat crop. But even Mustard 
is now threatened ; it is being victimised by a little blue beetle, which 
attacks it green or dry, young or old, both as -fly and grub, and 
threatens ruin to the crop.” 
Communication was also sent to myself early in the summer by 
Mr. A. L. Harrington, who, writing on the 1st of May from Rochford, 
Essex, mentioned that he had been asked to obtain information as to 
the name and habits of a little blackish beetle enclosed, which was 
then clearing off whole fields of Mustard and other plants. 
The Mustard Beetle is (as figured at p. 55, nat. size and magnified) 
short and oval in shape, and hardly as much as the sixth of an inch 
in length; legs, horns, and body beneath black, and above of variable 
tints of dark violet, blue, or greenish. Its life-history appears to be 
that the wintered beetles attack the Mustard, and presently lay their 
eggs, and in the natural course of things, after this, they die, and 
consequently disappear from the plants. Very soon the eggs hatch, 
the caterpillars (or grubs) spread themselves on the plants, devouring 
broadcast, and after a while they too vanish, but not like the parent 
beetles, because their term is ended, but because they have gone down 
into the ground to turn to chrysalids. They are stated to remain in 
this condition only fourteen days, and then from these chrysalids there 
comes up in full force the summer brood of beetles, carrying perfect 
devastation before it. Whether there is a second brood in England 
has not been reported ; in Germany caterpillars have been found in 
May and June, and again in September. 
* See ‘ lteport on Injurious Insects for 1882,’ Simpkin & Marshall. Published 
1883. f Ibid. 
