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AN ENCYCLOPADIA OF HORTICULTURE. | 
495 
Onion continued. 
Yellow Danvers. Bulbs of medium size, with small base and 
tine slender neck; flesh very firm throughout, of fine quality. f. 
eeps well. 
fine and distinct variety, which ripens off freely and 
See Fig, 741. 
The following are varieties of Onion that are distinct 
in habit from those already enumerated. They are useful 
to grow in small quantities, as sometimes they come in 
when others are not procurable. 
Egyp Tree, or Bulb-bearing Onion (GARDEN ROCAM- 
BOLE). This throws up a stem from the bulb, which has to be 
planted, and produces a number of small bulbules, about the size 
of marbles, on the top, that are excellent for pickling. Offset 
bulbs are also formed underground; and from these, and the other 
small ones produced on the stem, the variety is propagated. 
Perennial Tree or Top Onion. This is somewhat similar to 
the EGYPTIAN, but the bulbules are smaller, and none are pro- 
duced underground. The plant is perennial, and has long, fibrous 
roots. 
Potato or Underground Onion. A variety cultivated some- 
thing like Shallots. Small bulbs are planted singly, and around 
them new ones are formed. They are of irregular shape, of fair 
quality, and useful for an early supply. This variety is not pro- 
pagated from seeds. 
Welsh Onion. g a herbaceous perennial, with long, fibrous 
roots ; it forms ulbs. There are two varieties, the Red and 
the Green, cul for the use of their tops, or leaves, Propa- 
gated by seeds, or by division of the roots. 
>. ONION FLY (Anthomyia Phorbia ceparum). This 
insect is at times most hurtful to Onions, the larve 
burrowing into, and eating, the bulb scales, near the 
base, in companies of from two or three to one hundred, 
or even more. These attacks are very serious in some 
localities, the greater part of the crop being often 
severely injured. The bases of the thick leaf-scales rot, 
and the plants are easily pulled up, leaving the decaying 
bulb and the maggots in the soil. 
The flies are not unlike common house-flies in general 
appearance. They are of a blackish colour, thickly 
powdered with grey; the sides of the thorax are pale, and 
there are three dark lines on the back. In certain lights, 
the abdomen has a whitish lustre on it, with, in the male, 
a darker median stripe. The eyes are separated, in the 
FIG. 742. ONION FLY, LARVA, AND PUPA. 
1, Lines showing Natural Spread of hii p and Len; of Body of 
the Fly; 2, Line showing Natural Length of Larva. 
male, by a slender, black, white-bordered line; the face 
has a pale lustre, and the forehead is black, as are the 
antenne and palpi; the legs are pitch black, the wings 
being pale grey, and the poisers white. The length of 
the insect is about zin. In the female, the forehead is 
broad, with a reddish-brown, vertical median stripe, and 
the body is more ochreous in colour than in the male. 
Life History. The flies emerge, in early summer, from 
the brown pupe, which have remained all winter under- 
ground, sometimes in the Onion, but usually near it in 
the soil. The female generally lays her eggs, five or six 
on each plant, on the leaves, just above the soil; and 
from these emerge larvæ, which bore downwards in the 
soil, and into the leaf bases, causing the whole Onion 
ultimately to rot under their attacks. They are nearly 
| 5 
Onion Fly - continued. ; 
vhite, with yellow stigmas, smooth and shining, tapering 
ut headless) in front, and blunt behind. When full- 
fed, they burrow into the soil, and there become changed 
into chestnut-brown wrinkled puph. The fly, larva, and 
pupa, are shown in Fig. 742, and a diseased bulb in 
j GALS 
FAG ay 
Fic. 743. SECTION OF ONION ATTACKED BY LARVÆ OF ONION FLY. 
a, a, Groups of Eggs and Young Larve; b, Hole made by Larva in 
Entering the Bulb; e, Direction of Course followed by Newly- 
hatched Larva to reach Base of Bulb; d, Burrow of Larva, in 
Bulb, with Larva lying in it. 
Fig. 743. The entire development occupies from four 
to six weeks, so that several broods may appear in a 
summer. The first sign of attack by the larve is that 
the outer leaves become yellow, and fall, withered. The 
habitat in the bulbs protects the larve from injury, and 
from direct means of destroying them, unless the Onions 
are destroyed. 
Remedies. Prevention is better than cure; and, for 
the safety of future crops, it is well to dig up and 
remove any plants that show signs of turning yellow, 
especially where the flies have been observed. The 
diseased bulbs should be dug out carefully; and they, 
and any larve that creep out, should be destroyed. If 
this is done sufficiently early, all the larve should be 
got rid of; but if deferred, they will have left the 
bulbs, and have turned into pupæ in the soil, in which 
situation they are less easily reached. Deep trenching 
of the soil in autumn is of use to destroy the pups, 
and farmyard manure, dug in during the operation, 
strengthens the plants, Applications of soot or gypsum, 
and of gas-lime, to the soil have been found useful; 
as have also soapsuds, and water from pigstyes, and, 
best of all, the use of paraffin oil, in the proportion of 
about loz. or 20z. to a gallon of water. Sulphuric acid 
has been recommended, but is hardly suitable, as it 
is dangerous to the plants. Scattering the plants in 
small groups among other crops hinders the passage of 
larve from plant to plant. 
ONISC IDE. A family of Crustacea, popularly known 
-as Woodlice, or Slaters. The Crustacea include a large 
number of animals, which, like insects, have the body 
jointed, or forming rings of hard substance, to protect 
