THE FIG-MOTH[13] (_Ephestia cautella_)
All’ amico mondagli il fico.
(_Italian Proverb._)
The extension of the War to Turkey and Asia Minor has drawn attention
to the existence of certain insects whose larvae exercise a very
deleterious effect on valuable food-supplies in the Near East. The
inhabitants of Asiatic Turkey, without knowing it, have from time
immemorial adopted the advice of Captain Cuttle: ‘Train up a fig-tree
in the way it should go, and when you are old sit under the shade on
it. Overhaul the—— Well,’ said the Captain, ‘on second thoughts, I
ain’t quite certain where that’s to be found, but when found, make a
note of.’
[13] The figures illustrating this article are taken from _The Report
of the Fig-moth in Smyrna_, Bul. 104. Bureau of Entomology, Washington,
1911.
Asia Minor may indeed be described as the fig-ground of the East, and
anything that interferes with the fig as a food is likely to interfere
with the well-being of our troops in Egypt and the Near East. In
‘The Minor Horrors of War,’ I described a species of moth, _Ephestia
kühniella_, a member of the family Pyralidae, which infests and
destroys Army biscuits; but this other species, _E. cautella_, which
attacks figs, is even more troublesome than the one described in the
above-mentioned book.[14]
[14] It might be well to repeat the fact that the genus _Ephestia_
belongs to the family _PYRALIDAE_, which is by most authorities
included in the _Microlepidoptera_. The Speaker’s sneer at the
entomologists who work at this group (see his letter in _The Times_
of February 2, 1916) is hardly worthy of one of the chief trustees of
the British Museum. As a chief trustee, he must have been aware of the
exhibit of the Microlepidoptera, _E. kühniella_, and its devastating
action on the biscuits supplied to our soldiers by the War Office,
which has for many months occupied a prominent position in the middle
of the central hall of the Natural History Museum at South Kensington.
This exhibit showed how closely the study of the Microlepidoptera is
associated with the food-supply of our soldiers in many parts of the
world.
[Illustration: FIG. 32.—Typical Smyrna fig-orchard in Meander Valley,
Asia Minor, whence come the best figs for export.]
[Illustration: FIG. 33.—The fig-moth (_Ephestia cautella_). _a_, Moth
with expanded wings; _b_, denuded wings showing venation; _c_, larva,
full grown, dorsal view; _d_, two egg masses, _a_, _b_, _c_, About
four times natural size; _d_, more enlarged.]
Whoever has attentively eaten dried figs must from time to time have
become aware that there is something very defective in their flavour,
and on close inspection little clusters of débris will be observed
on the outside of the dried fruit—the dejecta of the larva burrowing
within—and numerous round holes can be detected through which the
larvae have made their entrance. If cut open and carefully examined,
one or two small white grubs may be found, which give the fig a
singularly sour-bitter and most unpleasant taste. This is the larva
of the moth, _Ephestia cautella_ which has for the last four or five
years been attracting much attention in the Levant market. From 15 to
50 per cent. of the figs exported from Smyrna, the great centre of the
fig-trade, are infected with this ‘worm,’ and active steps were being
taken before the War spread to the Near East to check its ravages. The
moth itself is very like _E. kühniella_, but readily distinguished by
an entomologist. Originally, it seems to have come from Asiatic Turkey,
but by the aid of commerce it has been distributed in a broad belt
all round the world within certain limits of temperature. Wide as its
distribution now is, it is equally catholic in its tastes. Perhaps it
does as much harm to the chocolate trade as to any other, attacking
the cacao-bean as well as the prepared article; all sorts of nuts are
infested. At one time it was thought that the oil of the nuts was the
attraction, but the larvae flourish just as well on rice and bran, on
dried apples, dried insects, maize, and a great variety of other more
or less nutritive substances.
But to return to the figs. So serious was the trouble felt to be in
the American fig-market that, in 1910, the authorities at Washington
sent Mr. E. G. Smyth of the Bureau of Entomology to investigate the
insect in Asia Minor, where the figs come from, and from his report the
following account is taken:—
The manner of the fig-harvest is as follows: During August the
figs are ripening on the trees, and are gradually dropping off to
be collected from the ground and laid on strips of reeds, called
‘serghi,’ a yard broad; and here for two to five days they dry in
the sun. When dried, they are packed in goats’-hair bags or woven
willow baskets, and carried by horse or by camel to the fig-depots
in the neighbouring villages. Here they are collected from the
whole district, mixed together, and re-sacked for transmission by
railroad to the coast. At Smyrna they are graded and prepared for
the market: the better kind being either ‘layered’ or ‘pulled,’
whilst the inferior fruits are strung on strings or exported in the
form of a mashed cake to make the ‘strawberry’ jam of the Western
breakfast-table.
[Illustration: FIG. 34.—‘Serghi’ of reeds laid in long rows, used in
large orchards. Over these the moths congregate by thousands at night.]
Mr. Smyth’s object was first to find out at what stage the figs become
infected by the moth, and then if possible to suggest preventive
or remedial measures. He minutely investigated every stage in the
preservation of figs, from the ripe fruit on the tree to the preserved
figs in the hold on the steamer bound for New York, and the conclusion
he came to is this: With very rare exceptions the eggs are never
laid on the fruit whilst on the tree. The first and by far the most
important infection is when the figs are gathered and exposed on the
reed ‘serghi.’ Then about seven in the evening the moths begin to
appear, and steadily increase in number as the evening wears on. The
actual deposition of the ova cannot be observed, for the moths get
down amongst the reeds and lay their eggs on the under surface of the
fruit—usually in some crack or abrasion—so that the newly hatched larva
can more easily make an entrance into the fig. From some ‘counts’ made
at Tchifte Kaive it appears that after an exposure of one night 29 per
cent. of figs were infested, after two nights 38·5 per cent., and after
three nights 44·5 per cent.
[Illustration: FIG. 35.—Figs packed by string method (reduced).]
A second and serious source of infection is at the village depots.
Before the figs arrive, there seem to be no specimens of the _Ephestia_
in the buildings; but with their arrival the moth appears, and so
favourable is the shelter from the heat and the wind, and so abundant
is the supply of figs as sack after sack is emptied on to the floor,
that soon the moth is more abundant in the depots than amongst the
‘serghi,’ and the wonder is that a single fig escapes infestation.
Fortunately, the time spent in the depots is short, often only a night;
were it much longer, the whole crop would suffer. On their way down to
the coast again there is little or no risk of the moth, but arriving
at Smyrna we pick up the insect again in the ‘khans,’ where the figs
are prepared for export, but in the larval form. Here, in August and
September, little trace of the insect is seen, the larvae are then too
small to emerge and pupate; but by October many full-grown larvae
may be found on the fig-heaps or crawling up the walls; a few pupate
inside the figs, and these probably produce the few imagines found in
the ‘khans,’ at the port of shipping. The unpleasantness of the larvae
crawling all about the ship greatly detracts from the pleasure of a
voyage on a vessel laden with Smyrna figs.
[Illustration: FIG. 36.—Pile of refuse-figs in a Smyrna ‘khan:’ On the
wall, above these figs, fig-moth larvae congregate in large numbers.]
With regard to preventive measures, there seems in many parts of Asia
Minor to be two crops of figs—one in May and June and one later. The
former produces a large, watery fig, unfit for sale. It is left to
rot on the ground, but it serves as food for the larvae which will
produce the myriad swarms of moths in the early autumn. Obviously
these worthless figs should be destroyed as completely as possible.
Equally obvious are the suggestions that the figs should be covered at
night with some cheap covering whilst on the ‘serghi,’ and screened
from the moth whilst in the depots, and their sojourn there should be
as short as possible. Measures for destroying the larvae in the fig
usually take the form of heat—either hot air, hot water, or steam.
Each is effective, and each has certain advantages and disadvantages;
still, the more progressive merchants of Smyrna were, before the War,
experimenting trying to find the best means of destroying the larvae,
and in time a uniform system will probably emerge.