298 
THE TROPICAL AGEICULTITRIST. 
[Nov. 1, 1899. 
they arrived should at once be throughly disinfected. 
In Bending stocks by Wardinn case, the larvse of 
the beetles may with advantage be included. These 
will complete their transformations during transit, 
and are more likely to survive the voyage than the 
adult insects. 
There are other natural enemies of tlie Coccidse 
that may some day be advantageously employed in 
the same way. Amongst the two- winged flies f /)i)^(c/((> 
we find the Lestophonus iceryce, which attacks the 
' Fluted-scale.' Nearly every species of scale insect 
is subject to minute internal parasites belonging to 
the wasp family ( llijmenoptera'). The family 2seuroptera 
supplies the 'Lace-wing flies,' the larvas of which 
are known as ' Aphis-lions,' from the voracious way 
in which they feed upon Aphides and scale insecte. 
Even the butteiflies moih^ (Lepidopteni) provide 
a few coccid-eatiug species, such as the caterpillars 
tf the butterfly tipalt/is cpius end of several months 
of the genus Euhleiitma. The ' lady-birds ' are in- 
cluded in the family Coleoptera. 
Besides natural enem'es belonging to the animal 
kingdom, scale insects are subject to diseases be- 
longing to the vegetable world. There are several 
parasitic fungi that render great assistance iu re- 
ducing the numbeis of our Coccid-pests. In Ceylon, 
during the wetter months of the year, the 'green 
bug' ( Lecaniiiiiiviride) dies off to a large extent, at- 
tacked by a greyish mould which, after killing the 
insect, spreads outwards as a delicate fringe of in- 
terlacing wtiitish threads. A bright orange-coloured 
fungus (Septoria ? sp.,) is useful in checking the 
increase of ( Fiorinia Jioi inicc &nA Chionaspis hida'cis 
on the tea plant, and Aspidiotiis auranlii on orange 
trees, A \ery s\mi\&v iuxig\x% ( Spli(ciostilhe coccophilu) 
that attacks Aspidiotiis perniciosus in Florida fU. S. A ^ 
has been the subject of some very interesting ex- 
periments to test the possibility of communicating 
the disease to previously healthy colonies of the 
insect. Dr. L. O. Howard gives the following parti- 
culars of the experiments :* — 
'An interesting and important development of the 
past two seasou's work has been the identification 
and study of the parasitic fungus, Splici'iostilhe cocco- 
pliUa. Professor Rolfs, of the Florida Station, has 
devoted a bulletin largely to the consideration of 
this fungus, v;hich, as previously stated, seems to be 
prevalent throughout the Southern States. He has 
shown experimentally that the fungus may be trans- 
ferred to trees affected with San Jose scale, and 
the disease produced among the scales. His process 
was to inoculate acid bread with pure cultures of 
the fungus, and three weeks later the application 
. was made in the following way : — A piece of the 
bread about an inch square was placed in cold water, 
and shaken until the bread was broken up and the 
spores distributed in the water. This water was 
then applied to the scaly tree by means of a sponge 
or clolh, or sprayed on. The applications weie 
made in Midsummer of 1896, and observations were 
made as to the results late in February, 1897. Four 
of his experiments resulted successfully, and three 
unsuccessfully, while in the eighth experiment the 
result was doubtful on account of the tree having 
died between the times of treatment and inspection. 
Twigs from Florida containing Sans Jose scales, 
infested by the fungus, were sent to Mr. Horace 
Roberts, at Fellowship, N. J., about the middle of 
June. On September 25th Dr. Smith found the 
fungus upon almost, if not quite, all of the trees on 
which twigs had been tied. A number of instances 
have come to our observation of the death of the 
scale in a wholesale manner from the spontaneous 
work of this disease, or from some other cause. 
For example, we received scale-infested cuttings iu 
January, 1897, from an orchard which was said to 
have been freed from scales by this fungus disease. 
Careful examination showed that upon one cutting, 
out of 183 scales, but four were living ; on a second 
cutting, out of 723, but two were living; on a third 
* Jiul/e'in, No. 12. (New Series.; fj. S. Depart- 
ment of Agriculture fDivifciion of Eutomology)- 
cutting, out of 579, but twenty-eight were living, 
thirty-four living scales out of 1485 — a mortality 
rate of 97-7.' 
I have, myself, repeatedly succeeded in diseemi- 
nating the disease iiffecting ifcnwitc/ji rZ/iWe by tying 
branches with diseased insects on to trees on which 
the bug had hitherto remained quite healthy. 
There are several methods by which spores of these 
parasitic fungi may be disseminted. As in the last- 
mentioned experiment, they may sometimes be 
communicated by mearly transferring affected bran- 
ches to the neighbourhood of the heiltby insects. 
In such cases ijje spores are carried by the wind 
to their destination. But in some of these fungi 
thr- sj ores are gelatinous and agglutinated, in which 
case the wind would fail to disperse them. Fungi 
of this kind may be ciu hed up in water and used 
as a spray ; or artificial cultures may be male and 
mixed with water, to be used i)i the same way. In 
the ordinary course of nature these gelatinous spores 
are probably carried from tree to tree on the feet 
of birds. 
Gexecal LiiT OF Substances and Puocesses Em- 
ployed IN THE TbEATMENT OF ScALE INSECTS. 
THE GAS TREATMENT. 
Hydrocyanic a?id gas is the material employed in 
this procefs. It is generated by the admixture of 
cyanide of potassitim, sulphuric acid and water. 
For the details of treatment I cannot do better than 
quote in exUiifo from the admirable paper on ' Gas 
Treatment for Scale Insects,' compiled by Mr, C. P. 
Louusbury from his rersonal experience as Govern- 
ment Eutcmolcgist at the Cape oi Good Rope. 
The process described was principally employed 
against .l.^j'idioitis aurantii — an insect that appears 
to be distiiictly cn the increase in Ceylon. I may 
sdd that I have followed Mr. Lounsbury's directions 
iu my own experiments with most satisfactory re- 
sults. 
' Generation of the Gas. — Hydrocyan'c acid gas is 
generated by the action of sulphuric acid on potas- 
sium cyanide in the presence ef water. The required 
quantities of the cyanide and water are first placed 
in the generating vessel, the cyanide being broken 
into small pieces not above the size of lump sugar. 
The tree is then covered with the tent or sheet and 
vessel slipped under almost to the base of the tree ; 
reaching in, the operator then adds the acid, pouring 
it slowly into the vessel so as to avoid its splashing 
an thus burning his hand or the cloth. He imme- 
diately withdraws and the men shovel a Jittle soil 
on the edges of the cloth all around, to more 
throughly prevent the escape of the gas. 
'The rapidity of the evolution of the gas depends 
largely upon the size of the pieces of cyanide. If 
these are like powder, the reaction is violent and 
immediate ; but, if in lumps, the reaction takes 
place more slowly and continues for a minute or 
longer. The slow reaction is desired, partly because 
less injury results to the foliage immediately above 
the vessel. But the lumps must not be too large, 
for then the reaction is liable to be imperfect owing to 
a black coating (carbon ?) forming over the lumps 
and preventing further decomposition by the acid. 
The water should not be added too soon or part 
of the cyanide becomes dissolved and gives a violent 
reaction. The residue which remains in the dishes 
is buried and ; the dishes are washed in clean 
water before being again used. 
' Tiwe necessarij for Treatment . — The cover is left 
over the tree for thirty minutes in the case of small 
trees, and forty-five in the case of those over twelve 
feet in height. At the expiration of this period the 
generating vessel is removed, and the residue buried 
in the soil. 
'A number of trees aie fumigated together, the 
endeavour being to treat as many at a time as can 
be covered and uncovered during the period of ex- 
posure. In this way the men are kept continuously 
busy, the time for the removal of the first tent 
arriving by the time that the last tree is covered. 
