Mustard Beetles. 
275 
The observations of the past season have also proved that, 
besides the injury caused by the true mustard beetle, much harm 
is done to the mustard plant by various kinds of turnip- " fly," or 
flea beetles, which attack it as they do the turnip-plant, whilst 
still in its first or early leafage. Those who are unacquainted 
with these beetles may readily distinguish them from the 
mustard beetles by their being much smaller, and also by their 
prodigious powers of leaping, and commonly by their having a 
yellow stripe running down the middle of each wing-case. 
The species which has occurred most plentifully amongst 
those forwarded has been the Haltica (^Phyllotreta) undulata, 
which differs so slightly from the P. nemorum, of which a figure 
Fig. 2. — Turnip-Flea Beetle (Haltica (Phyllotreta) nemorum). 
1, beetle, magnified ; 2 and 3, natural size ; 4 and 5, eggs ; 6 and Y, burrows made by the maggots ; 
8 and 9, larva, natural size and magnified; 10 and 11, pupa, natural size and magnified. 
is given (Fig. 2, which, with Fig. 4, is inserted by permission 
of Messrs. Blackie & Son, of Glasgow), that the two kinds 
can hardly be distinguished by the naked eye. Both have a 
yellow stripe along the wing-cases. The turnip-flea beetles 
pass the winter under clods or rubbish, or in any convenient 
nook, and, like the mustard beetles, come out in spring to feed 
on the same class of plants as these, and to lay their eggs on 
the leaves. 
Later on, in the growth of the mustard plant, just when it is 
knotting for flower, the opening buds and blossoms are very 
often attacked by large numbers of the turnip-blossom beetle, 
the Meligethes seneus. This is a small beetle (Fig. 3), of much 
the same shape as the mustard beetle, and, as far as I gather, it 
is frequently taken for it, but it is distinguished by its much 
smaller size, being little more than one-twelfth of an inch in 
length, and commonly of a duller or more brassy green than 
the true mustard beetle. 
T 2 
