THE TEOPICAL AGRICULTURIST. [Jan; 1, 1904. 
produce fruit. Under very favourable circumstances, 
by aelecting the finest suckers, and planting out at 
the earliest opportunity, a larger percentage of the 
plants will fruit. The plants -which have fruited 
usually produce from one to four new plants. All 
but two cf these to each plant are removed for 
setting out. The suckers which are left on the 
parent plant produce the second crop a year later, 
BO that for a second crop it is not unusual to harvest 
fifteen thousand, or more, fruits from the acre which 
lifts been set out to twelve thousand plants, 
In the pine woods and the fpruce-pine land, the 
favourite method of planting pineapples at the present 
time is to lay the ground off in beds of about six 
rows, the rows being planted about twenty inches 
apart, the plants about twenty inches apart in the 
row. Fields, laid off into these narrow beds are 
much more cheaply worked and fertilized than when 
laid off in a solid block, 
THE 6HED SYSTEM OF CULTIVATION. 
One of the greatest factors in the success attained 
in Florida has been the introduction of the shed 
system of cultivation, and now over hundreds of acres 
stretch low shedding, equalising the temperature 
greatly the whole year round. The best vines are 
raised under these sheds — and the expense of building 
a shed usually staggers a beginner — it is something 
like £80 per acre. The pineapple " shed " is a modi- 
fled form of greenhouse, the roof of which has as 
much snace open as covered, it is about 7 feet high, 
and built of hardwood and pinelaths. The object of 
the shed is to reduce the temperature in summer, and 
increase it during the winter. The advantage of 
shedding are these ; (1) An increased amount of 
nitrogen is developed in the soil. ; (2) the texture of 
the fruit is improved ; (3; the size of the fruit is 
increased about twenty-five per cent. ; (4) the tempera- 
ture is reduced in summer, and increased in winter. 
Many acres are now shedded where the danger from 
frost is qaite remote. One of the largest sheds at 
the present time shelters a half-million plants, and 
covers forty acres. The cost of such a pineapple shed 
is about £30 per acre. This, of course, may be con- 
siderably reduced as the area is increased. The 
following bill of lumber gives approximately what 
it takes to build a shed for a single acre:— 463 
posts, 4 by 4 inches by 9 feet ; 266 striogers, 2 by 
6 inches by 16 feot ; 5,900 laths, 1 by 3 inches by 16 
feet, for cover; 450 boards 1 by 12 inches by 16 feet, 
for sides. 
THE METHODS ON THE FLORIDA KEYS. 
The Florida Keys are famous for pineapples- 
Here the growers set out their plants in a mass 
of rubble, equalled ouiy by the refuge from the 
rock-quarry. Sometimes there is no leaf-mould left 
after cleauing, and it becomes necessary to brace the 
newly-3et plant on all four sides with rocks to keep 
it from falling over. No cultivation is given, as it 
ia impossible to use a plow oi even a hoe. Young 
plants are usually set out within a few weeks after 
the crop on the old field has ripened, and are allowed 
to have their own way for several months, when 
Iftbonrers are employed, who use large knives to cut 
out the weeds that may have sprting up, or whatever 
shrubbery may not have been killed by burning 
over in oleariog. It may be necessary to go over 
the field a^ain before the first crop comes in, but 
ordinarily one weeding is sufficient. In this section 
It is impossible to plant in rows, as the plants have 
to be set out wherever possible at convenient distances 
from each other. By the time the second crop is 
ripening, the foliege will be so dense that tlie 
ground is completely shaded. Fertilizing is not 
practised in this section. 
The pineapple plantation on the Keys produces 
crops for from five to ten years, when the field is 
said to be " run out," Then Nature is allowed to 
claim her own, and the sturdy " (Jonch " moves oa 
to a new field. Unfortunately, the ambitious from 
other seoticns of the country have entered the field, 
and the end of this comfortable system is practic- 
ally in sight, — Agricultural Journal. 
THE COTTON WORM. 
THE DSE OF PARASITES TO COMBAT IT, 
Among insects, as among all other groups of animals 
and plants, there is constantly going on a keen 
struggle for existence. Insects are preyed upon by 
animals in other orders such as birds, toads and lizards, 
and by other insects, examples of which are very easy to 
find. The wild bees eat caterpillars ; the dragon-fiies or 
pond-flies capture and devour butterflies, grasshoppers 
and even other dragon-flies; lady-birds (coccinellidsjeat 
plant lice and scale insects. Many more examples 
might be given. In addition to these predaceons 
insects, there are others still more common and much 
more effective in checking extreme outbreaks of insect 
pests. These are parasites, and they are extremely 
abundant. 
Parasites are cf two kinds — external and internal. 
Examples of the former are the very familiar reddish 
mites found attached to the body and wings of grass- 
hoppers. These act in a similar way to those parasites 
of the higher animals, the lice and ticks of man, 
cattle, dogs, fowls, etc. In the Insect realm internal 
parasites are of much more importance than external. 
These have a wide range in habit, structure and 
relationship, but the commonest are certain two- 
winged flies {Diptera), and certain of the wasp-like, 
four-winged flies {Hynienopte.ra). Insects of nearly all 
orders are attacked by internal parasites, and the 
attack usually results in the destruction of the indi- 
vidual attacked, or the host, as it is called. 
Two of these internal parasites have recently been 
reared from pupae of the cotton worm by the Entomo- 
logist on the staff of the Imperial Department of 
Agriculture. A large number of pupae was kept in 
boxes and jars under favourable conditions for the 
moth to emerge. After eight days no more moths 
emerged, but on the ninth and subsequent days a 
number of small flies appeared and a few small black 
and white Hynienoptera. Although at present nothing 
is known of the early stages of these insects, yet it ia 
possible, from our knowledge of other similar insects, 
to give a general account of the life-history of each. 
This parasitic fly is at first glance not unlike the 
common house-fly, but comparison shows it to have 
more bright colours on the head, and the body ia 
covered with rather long, stiff hairs. It belongs to 
the family T achinidae or Tachinid flies, nearly all of 
which are parasitic. 
The adult female has no sting or ovipositor, so that 
when the eggs are laid they are merely fastened upon 
the skin of the caterpillar which is attacked. It the 
caterpillar sheds its skin at once, the egg may be cast 
off with it, but it generally happens that the egg 
hatches before the moulting of the skin takes place. 
In this case the small, white, footless maggot, which 
comes out of the egg, immediately bores its way 
through the skin of the caterpillar, which is now the 
host, furnishing both food and protection to the ua- 
welcome guest. Here this small maggot lives and 
grows, feeding on the vital fluids of the host. In epite 
of this tax upon it the caterpillar is able to go on to 
the pupa stage ; bat when this is reached and no more 
food is being taken in to supply the demands of the 
maggot, the guest eats up the host itself. All the 
concentrated energy and dormant lifei which should 
go to develop a moth capable of reproducing its kind, 
is converted into a fly, whose object in life is to live at 
the expense of some other insect, and so instead of a 
moth there emerges from the cocoon a fly. The 
hymeuopterous parasite differs from the fly in the 
method of depositing its eggs. This one has a sting* 
like ovispositor, by means of which it is able to insert 
its eggs under the skin of the caterpillar, and tbea 
there is no escape for (be unlucky host, 
