April i, 1890.] 
THE TROPICAL AGRICULTURIST. 
REPORTS ON THE PADI (RICE) BORER, &c. 
The following reports, by the Curator, Museum, are 
published for general information. By command, W. 
H. Treacher, Secretary to Government. 
Government Secretary's Office, 
Taiping, 25th March, 1889. 
My attention was called to this subject, by a letter 
dated the 1st of January, 1887, that was for- 
warded to me by H. M.'s Assistant Resident of Perak 
from Dr. Leech, the Collector and Magistrate of the 
Krian District, in which he says : — 
"With this letter I have the honour to forward 
you a bottle containing some specimens of a maggot 
which is at present playing havoo with the padi crop 
here. This is the third season I have heard of its 
attacks, and each year has been worse than the pre- 
ceding one. The time, it appears, is just as the ear is 
beginning to form. Many (maggots) are found in 
one stalk, the whole inside of which becomes brown 
and rotten. I have seen acres of padi attacked in this 
way, with the stalks and ears complete, but without 
a single grain of rice in them. It appears that it 
makes no difference whether the land is dry or wet. 
I have not been able to ascertain what sort of insect 
produces these maggots. If any method of destroy- 
ing them could be got, it would be a great blessing 
to the people of this district, as the ravages com- 
mitted by this maggot far exceed those of the rats or 
pigs — the other enemies of the padi crop. Perhaps 
the Curator of the Museum or H. M.'s Resident may 
know something of the habits of this pest, and sug- 
gest some means of destroying it. On the 12th Janu- 
ary, I suggested the burning of the straw after the 
harvest, and Dr. Leech sent out a Malay notice re- 
commending this course to the cultivators in his dis- 
trict. Since January I have visited the padi-fields, 
and have procured specimens of the caterpillars, which 
I have kept, and have bred from them the perfect 
insects. The results of these observations I will now 
proceed to detail, beginning with the description of 
the various stages of the Padi Borer Moth. 
Description. 
Chilo species affin. C. Oryzmellus of Riley. 
The egg. is oval-shaped and white, faintly tinted 
with green. It has a finely pitted surface, with some 
irregular, longitudinal creases. They are laid in masses 
of thirty or more together, in a slanting, overlapping, 
double, treble, or more extended series, and are firmly 
cemented together and to the leaves on which they 
are laid. The egg is about 3-100ths of an inch long 
by 15-1000ths of an inch wide. 
Larva.— Head dark brown, polished, furnished with 
a few stiff brownish hairs, a median yellowish line. 
Cervical shield varies from light to dark brown, with 
a median yellowish line. Colour of body pale yellow- 
ish white, slightly transparent, marked with five rather 
indistinot, pale, purplish stripes, of which those 
bordering the stigmata are scarcely half as broad as 
the other three. The pilifeious spots are oval, yellow- 
ish coloured, and polished, stigmata small, trans- 
versely oval, brown, the last pair twice as large as 
the others; these latter are sometimes pale centered. 
Anal plate yellowish, polished, furnished with a row 
of three hairs upon each side and two near middle ; 
it is marked with a few purplish spots. 
Length 7-8ths to 1 1-I0th inch. Diameter, l-10th 
to 3-20th inch. 
Pupa. — Colour pale yellowish brown, with five brown 
longitudinal stripes. As it nears maturity it assumes 
a dark brown colour, wing cases paler, and with a 
pearly lustre. Head bent forward, its front some- 
what pointed. Thorax with very fine transverse 
strhe. Abdominal joints, armed dorsally, near their 
anterior margin, with numerous very minute brown 
thorns. Stigmata projecting. Tip of last joint oonical, 
with a longitudinal lateral impressison ; expanding 
dorsally into two flattened projections, each being 
divided into two broad teeth. There are also two 
projections from the lowor surface of the last joint, 
one on each side of the longitudinal impression. 
Length 3-10th to 6.10th inch, and diameter 3-lOth to 
1 10th inob. 
Imago. — Male, above, general colourpale ochraceous. 
Anterior wings, with an irregular oblique fuscous fascia, 
from about the middle of inner margin to near the apex 
of wing. Costal and posterior margins ochraceous, fringe 
golden. A marginal Hue of seven small brown spots 
and a submarginal line of shining golden brown spots, 
along the posteiior margin, but curving away from the 
apex. Some of these shining spots are also scattered 
over the oblique fuscous fascia, more thickly near the 
end of the cell. Hind wings paler and unmarked. 
Beneath, anterior wings dull yellowish, sometimes 
sullied the dirty brown. Hind wings the same, but 
only slightly tinged with brown on the costal region. 
Body and legs same colour as palest part of wings. 
Labial palpi bushy, and slightly broadened at tip, 
horizontal, nearly as long as head and thorax together, 
a few dark scales and hairs intermixed with the paler 
ones. Maxillary palpi prominent, with only a few 
dark scales. Eyes black. Antennas more than half the 
leugth of the costal margin of the anteior wings, fili- 
form, clothed with pale ochraceous scales. Expanse, 
7-10th to 8-10th inch, and body 3-10th to 4- 10th inch 
long. 
The female differs in being duller in colour and in 
the fascia on anterior wings being very indistinct. 
Beneath dull pale ochraceous. .Labial palpi more bushy 
and larger than in the male. Expanse 19-20th of an 
inch, and body | inch long. 
This insect evidently belongs to the genus Chilo of 
Zincken-Sommer, ana may not be specifically distinct 
from C. Oryzceellus of Riley, as the differences noticeable 
in it may be only of a varietal character. 
A comparison with the type specimen would be 
necessary to determine this point. C. Oryxaellus is 
an insect of much the same habits as ours, and found 
in North America. 
Natural History and Habits. 
The eggs are laid in white irregular shaped masses, 
which may measure as much as j inch in length, by 
nearly 1-10 inch in width, on the leaves of the padi 
plant. The eggs after a few days become greyish, 
from the formation of the young caterpillars inside 
them. In the case of one female that I reared, eleven 
such masses were deposited in one night, and seven the 
next. One mass that I counted under the miecn> 
scope contained 39 eggs, so that it would be safe to say 
that one female will lay as many as 600 eggs. As 
there was not muchchoico possible in this case, nothing 
could be gleaned as to the part of the plant which would 
be selected, in a state of nature, by the female to deposit 
her eggs on, except that no eggs are deposited on the 
stem of the plaut. Judging from the position of the 
young caterpillars, the part selected is at the junction 
of a young leaf with the stalk. 
From this point, as soon as the eggs are hatched, the 
young caterpillars eat their way into the tender shoot 
or into the midrib of the leaf, in the case of the first 
brood, as will be mentioned further on. On exhaust- 
ing the supply of food in the growing shoot, they 
bore out and re-enter the stalk lower down. 
The caterpillar makes a nearly circular hole where 
it enters a stalk, which it closes up from the inside 
with focal pellets and some fine white silk, and some- 
times with the latter substance alone. When a cater- 
pillar has eaten all the inner lining of one joint, or as 
much of it as it fancies, it either bores out again and 
enters another joint, usually lower down the stalk, or 
it bores through the substance of the joint itself. This 
latter method of seeking for a fresh supply of food I 
have seen adopted on several occasions, both in the 
straws picked in the fields aud also in those I have 
kept for purposes of observation. Sometimes it is the 
bottom of a joiut, and sometimes the top, which is thus 
perforated. The stalks are usually more eaten near 
the joints than elsewhere, and often the film remaining 
is so thin that the stalk breaks short off. When the 
caterpillar is short of food, it will feed on the inner 
lining of the leaf-stalks. This has happened in my 
breeding experiments, and I have also noticed it in the 
fields. 
In the first brood of the season, the food of the 
carterpillar is principally supplied by the growing 
