208 
THE DICTIONARY OF GARDENING, 
Potato—continued. 
is in the soil, it should be either removed or counter- 
acted. - Potatoes should not be grown in soil known to 
give rise to scabbing. 
Insect Pests. There are no insects, in the British 
Islands, absolutely confined to the Potato as their food; 
but several occasionally devour this, as well as other cul- 
tivated plants. To begin with those that eat the roots 
and tubers. Amongst the worst are the larvæ of several 
— * 
Fig. 258. SKIPJACK, OR CLICK BEETLE—a, Line showing 
the natural length. 
kinds of Skipjack Beetles (see Figs. 258 and 259), 
which bore holes in the tubers, to which they are very 
partial (see Wireworms). The larve of Cockchafers 
(Melolontha vulgaris) and Mole Crickets (Gryllotalpa 
vulgaris) also gnaw them, and the roots at times (see 
Cockchafer and Mole Cricket). 
The larvæ of certain Noctue, or Night 
Moths (see Noctua and Turnip 
Moth), are sometimes very destruc- 
tive to the tubers, but do compara- 
tively little harm to the other 
subterranean organs, since, as a rule, 
they do not feed at the season of 
growth of Potato-plants.. Among the 
most harmful are the Heart-and-Dart 
Moth (Agrotis exclamationis), the 
Turnip Moth (A. segetum), and nearly- 
allied species. The larve of Crane 
Flies (Tipula oleracea and allies), 
commonly known as the Grub, or 
as Leather Jackets, because of the 
toughness of their skins (see Crane 
Fly), frequently injure the roots of 
growing Potatoes, and may also feed 
on the young tubers, though most de- 
structive to grasses. Many kinds 
of small Diptera live, as larve, in 
decaying Potato tubers, and Curtis, 
in his “Farm Insects,” has recorded 
ten species reared by himself from 
this food; but there is no evidence 
to show that they injure healthy 
tubers. Millipedes, including Poly- 
desmus complanatus, and one or two species of Julus 
(see Millipedes and Myriapoda), are often found 
feeding in the tubers, but they hardly seem to bore 
into them if quite healthy, and, in general, appear to 
take advantage of holes scooped out by the larve 
already mentioned, or to bore into tubers which are 
softened by disease. Centipedes also (see Myriapoda) 
are often found in holes in the tubers, but they are all 
Fie. 259. WIREWORM, OR LARVA OF SKIPJACK BEETLE. 
carnivorous, and probably assist in reducing the number 
of destructive larve. Last of the animals that destroy 
the tubers, must be mentioned the various kinds of Slugs, 
which eat large holes in them, and continue to feed in 
these till, occasionally, there is little left of the smaller 
tubers (see Slugs). Sings do not seem to do much 
harm to the green parts of Potato-plants. 
The green stems and the leaves are not, as a rule, 
liable to severe insect attacks with us, though in North 
Potato—continued. 
America ‘they suffer much damage from this cause. The 
more injurious of these American insects will be here 
briefly referred to after mention has been made of such 
as have been observed in Britain. 
Curtis records finding a beetle (Macrocnema exoleta), 
allied to the Turnip Flea, feeding on the leaves of 
Potatoes, and still more abundantly on the Bitter-sweet 
Solanum Dulcamara). The beetle has the head black, 
the thorax deep ochreous, the elytra pale ochreous, 
except a pitchy line down the suture, and the limbs 
pale. It is from in. to fin. long. These pests can 
scarcely be ranked as a serious danger to the Potato 
crop, but, should they become dangerous to it, they may 
be reduced in numbers by the same methods as are 
employed against the Turnip Flea (which see). 
Of moths, few live, in the larval state, on Potato 
leaves; but one species is almost restricted to this 
plant—the Death’s Head Hawk Moth (Acherontia Atro- 
pos). This moth (see Fig. 260) is one of the largest 
and handsomest of our native species. The appear- 
ance, form, and markings, are shown in the woodcut; 
but the spread of wings may be 5in. The fore wings 
Fig. 260. DEATH’s HEAD Hawk MOTH. 
are a fine brown, with darker and paler markings, and 
a conspicuous yellow dot in the centre. The hind 
wings are orange-yellow, with two.dark bands. The 
body is yellow and brown, with six black cross bands on 
the abdomen, and a row of six bluish spots down the 
middle of the back. The thorax bears, between the fore 
wings, a large mark, like a skull, or “Death’s head,” 
whence the popular name. Because of this mark, also, 
the insect is much dreaded, in various parts of Europe, 
by superstitious rustics and others, as ill-omened; and 
this impression is deepened by the power (very rare 
among moths) of emitting a sharp squeak when 
handled. The larva and pupa can also emit peculiar 
sounds. The larva feeds now chiefly on Potatoes; though 
it has also been found on the Jasmine, the Deadly 
Nightshade (Atropa Belladonna), and the Tea -tree 
(Lycium barbarum). It reaches a very large size, tapering 
a little towards the head, but ending abruptly behind, 
where it bears a small horn, very rough, yellowish, 
and bent downwards, but turned up at the tip. The 
creature is smooth, and is usually pale yellow on the 
back, and green near the head and along the lower 
part of the sides. There are seven oblique, violet or 
