674 
THE TROPICAL AGRICULTURIST. [April i, 1890. 
shoot, and the interior of the midrib of the leaves and 
leaf -stalks. This first brood reaches maturity before any 
appreciable amount of hollow stalk is formed by the 
padi, aBd hence this change, in what may be considered 
its normal habits, is necessary, to adapt itself to its 
environment. The pupse of this first brood are nearly 
always found in the leaf-stalks. In subsequent broods 
they are generally found in the inside of the stalks, 
sometimes above the hole of entrance and sometimes 
beneath it. The pupse are usually more or less enclosed 
in a fine white web, and the head is, in all cases that 
have come under my observation, uppermost. 
The larva? are able to progress wiih nearly equal 
facility either backward or forwards, but they are not 
active at any time, and when disturbed generally 
remain quiescent. 
In a single stool of young padi, I found no less than 
20 caterpillars.- This plant was found growing by 
itself in Taiping, and not near any padi fields, pro- 
bably the nearest being more than two or threi; miles 
away. Thia seems to show either that the moths take 
long flights, or that some wild plant serves as food for 
the caterpillar as well as padi. 
When kept in confinement, the moths sit quite still 
all day, and by preference on the earth at the bottom 
of the breeding cage. It seems, therefore, probable 
that they sit usually on the dead leaves of the padi 
during the dav-tiine, ami, as their colour so nearly 
assimilates to it, this would be a position of great 
eeourity. I have hunted over a field of padi for them, 
but without success, though the straw was full of full- 
grown caterpillars and also of minute ones, and there 
must have been many of the moths about. In the day 
time, it is difficult to get them to fly, even when 
touched, but at night they are fairly active and seem 
to be able to fly well. 
The female begins laying her eggs on the second 
night after coming out of the chrysalis, and they hatch 
out on the fifth day, the female dying in about seven 
days. The eggs seem to be all laid on the second and 
third night. The males, in a state of captivity, only 
live from three to four days. The anteise of the moth 
are carried, laid back on the wings, aud have to be 
looked closely for, or they will pass unnoticed. 
Usually only one caterpillar is formed in a stalk of 
padi, but I have found as many as five on one or two 
occasions. Judging from the breediLg experiments, 
several stalks may be required to afford sufficient food 
for the support of a single caterpillar. 
Number of Broods. 
On the 29th April, or more than six weeks after the 
harvest in this district, I found in the padi stalks 
several minute caterpillars, as well as many more 
advanced ; in fact, they ranged from one-eight of an 
inch to full-grown ones. I also examined a young stool 
of padi, and found in it four or five chrysalides. This 
clearly shows that a brood haB time to mature before 
the padi has begun to throw up stalks, and, taken with 
the presence of the caterpillars in all Btages in the Btraw 
after the harvest, it is probable that these broods arriva 
at maturity before the harvest, and that there are three 
more between then and the next planting, making about 
six in the year. That would be two months for each 
generation. 
Natural Enemies. 
Out of one lot of four grubs raised by me, three were 
destroyed by the larva of some other insect, and on an 
examination of a padi field one day I found no less 
than five live pupie and three empty cases of the same 
parasite, and not one single live pupa of the rice borer, 
and only two or three empty cases. This parasitio 
larva is, therefore, one of the most powerful aids in 
checking the increase of these destructive pests, and 
it would seem that, without its help, the cultivation 
of padi in the Malay fashion would be quite impossible. 
The parasitic insect to which we are so much indebted 
B a (ly, in appearance much like a common house-fly ; 
and its larva is a small white maggot, which is either 
iaid in or on the body of the rice borer, and which lives 
inside its body and soon destroys it. 
Description. 
Order, Diptera. Family, Muscidse. 
Tachinariae. | Genus and Species. (?) 
Larva. — Milk white and semi-transparent. Skin 
shiny, the anterior and posterior quarter of each 
segment armed with minute brown thorns. Cylindrical, 
with the head not distinct from body ; which is 
abruptly terminated posterierly and conically anteriorly. 
On last segment a pair of warm brown Btigmata. 
Mouth furnished with two black hook-like organs. 
Length of a full-grown one, that I extracted from a 
dead padi borer, half an inch, and diameter, one-eight 
of an inch. 
The thorns on the body of the maggot are evidently 
the means of locomotion inside the body of its host. 
In two padi borers that I opened the head of the mag- 
got was towards the tail of its host. The larva is very 
difficult to kill, withstanding immersion in spirits for 
a period of t wo and a half hours. 
Pupa. — Cylindrical, with rounded ends, of a warm 
brown colour. Length 9-20th inch, and 5-40th inch in 
diameter. 
The insect continues in the pupa state from twelve 
to thirteen days. 
Imago. — Head silvery grey with red brown eyes and 
black bristles. Antenna? with three joints, of which 
the last is the largest, a single long hair projecting 
from near base of third joint. Palpi consist of a single 
joint. Above, thorax black with grey stripe on each 
side and two others on the dorsal aspect. Scatellum 
grey, except central portion, which is black. Abdomen 
black, with three silvery transverse stripes, partly 
interrupted on the median line. Hairs on abdomen 
black, conspicuous on the two last segments. Wings 
hyaline, iridescent, unmarked ; halteres covered by 
large milk-white scales. Beneath wholly black, except 
three faint grey transverse stripes on abdomen. Legs 
black. Length 7-20th inch and 6-10ih inch across 
wings ; the female is a little larger. 
In confinement these flies live from four to five 
days. I have not been able to observe the method in 
which the fly gets at the padi borer to lay its egg, or 
young, as the case may be ; but it is probably when 
the latter leaves one joint of the stalk in search of 
more food that the fly effects its purpose. 
Effects on the Crop. 
As I have already stated, the first brood of cater- 
pillars matures before the rice has made any stalk, and 
that its food consists of the midribs of the leaves and 
the growing shoot. This leads to the death of those 
young shoots which are infested by the borer. The 
next brood which pass their lives inside of the stalk 
are those which cause the abortive ears of rice, and 
are, therefore, the most destructive to the crop, though 
the first brood killing the growing shoots of course do 
very considerable damage. In the letter I have already 
quoted, Dr. Leech has given his experience in the Krian 
District, and from what I have seen in Larut, nearly 
as much loss has been inflicted on the crops here. 
Preventive Measures. 
By the Malay way of harvesting, only the ears of 
the padi plant are cut. and the straw is left standing 
in the fields until the next planting season comes 
round. Hence all the caterpillars and chrysalides have 
an opportunity of maturing and continuing the species 
to the next season's crop. The perpetuation of the 
race from one season to another is undoubtedly carried 
on through the self-sown rice aDd the lateral shoots 
of the old plants, though it is possible that some 
large-stemmed grass may play a minor part in the 
matter. I found, six weeks after the harvest, in this 
district, that the straw was swarming with caterpillars 
of all ages ; and I was informed by the Malays that 
the shoots of the old plants and the self-sown rice 
would continue alive until the land was broken up 
again for the next planting ; so that food is available 
throughout the year for the sustenance of the suc- 
cessive broods of caterpillars. A consideiatiou of these 
facts, as well as of the life history of the borer, leads 
to the conclusion that the method which is most likely 
