72 
MUSTAKD. 
Descriptions and notes of various kinds of beetles injurious to the 
Mustard crop. Phmlon hetulm, Linn. ; Mustard Beetle (see fig., p. 58). 
The beetle, which is especially known as the Mustard Beetle, is the 
Phadoii hetulm, Linn., formerly the ChrysomeJa hetulce (see fig., natural 
size and magnified;; it is oblong-oval, hardly the sixth of an inch in 
length, of a full blue or greenish colour above, so brightly shining as 
to be of almost glassy lustre. The leg, horns, and body beneath 
black. The thorax (or fore body) evenly punctured, the wing-cases 
with lines of punctures, and the spaces between these punctured also. 
These beetles pass the winter in a torpid state, in any convenient 
shelter near the fields where they have been in autumn. In spring 
they become active again, and, spreading to whatever food-plant may 
be near, they lay their small eggs and die. The grubs which hatch 
from these eggs are of the shape figured, and are from about three- 
sixteenths to a quarter of an inch in length when full-grown ; slightly 
hairy, of a smoky colour spotted with black, with black head and stout 
black conical horns, lighter at the base. They have three pairs of 
claw-feet and a caudal foot or proleg at the end of the tail, and along 
the sides of the body are a row of tubercles, from which the grubs 
have the power of protruding a yellow gland. 
These voracious grubs devour broadcast until, when full-fed, they 
go down into the ground to turn to chrysalids. In this state they are 
said to remain about fourteen days, and from these chrysalids the 
summer brood of beetles comes out, which often spreads devastation 
over the Mustard crop, which is then in an advanced state. 
This is the history of the true Mustard Beetle, but the observations 
of the past season have shown that harm is caused to Mustard by 
various kinds of Turnip Flea-beetle, or Turnip Fly, as it is commonly 
called. The following observations refer to this attack:— 
‘ ‘ The Turnip Fly is sometimes a great trouble by eating the plant 
when it first comes up.’^— Ernest Smith. 
“ I send you another specimen of the pest, which I believe is the 
real cause of the mischief, for I have to-day ‘ caught him in the act.’ 
. . . They are very difficult to catch, as they hop oft' the Mustai’d so 
very briskly, and the one in the quill is the only fellow I could get 
there. ... I can find no Mustard Beetle in the field, and my belief 
is thereby strengthened that the ‘ flea ’ now sent is the cause of all the 
mischief. I enclose a little bit of the Mustard-leaf: scarcely a plant 
can be seen of the original sowing.”—W. Abbott. 
The specimen sent was of one of the yellow-striped flea-beetles 
known as Plujllotreta undulata. 
* The description given by John Curtis, in his ‘ Farm Insects,’ of a larva which 
he considered would turn out to be that of the Mustard Beetle, precisely agrees 
with those from which 1 developed the beetle last summer.— Ed. 
