Group Title: Press bulletin
Title: The manatee snail, Bulimulus dormani
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Permanent Link: http://ufdc.ufl.edu/UF00090411/00001
 Material Information
Title: The manatee snail, Bulimulus dormani
Series Title: Press bulletin
Physical Description: 4 p. : ; 21 cm.
Language: English
Creator: Sellards, Elias Howard, b. 1875
University of Florida -- Agricultural Experiment Station
Publisher: Florida Agricultural Experiment Station
Place of Publication: Gainesville
Publication Date: 1906
 Subjects
Subject: Oranges -- Diseases and pests -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by E.H. Sellards.
General Note: Caption title.
General Note: "Jan. 15, 1906."
General Note: At head of title: Department of Entomology.
 Record Information
Bibliographic ID: UF00090411
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 80159218

Full Text


Press Bulletin No. 59.


FLORIDA AGRICULTURAL

Experiment Station.

DEPARTMENT OF


ENTOMOLOGY.



The Manatee Snail, Bulimulus Dormani.
[By E. H. SELLARDS.]
The sooty mold of the orange, JMeliola, is one of the
most serious results of white fly infestation of citrus
groves, and is an element in the injury to various plants
from aphids and from some of the scale .insects, especial-
ly the Lecaniums, mealy bugs, wax scales, and cottony
cushion scale. The fungus is not itself a parasite on the
plant, but a saprophyte, deriving its sustenance from the
sweeet honey dew secreted by these insects. The injury
to the plant results from the smothering action of the
fungus, the heavy coating of fungal threads interfering
with the healthful action of sunlight on the leaves. The
appearance of the various ornamentals and hedge plants
is also disfigured by the dark fungus. The sooty mold is
especially bad following the white fly attack owing to the
large amount of honey dew secreted by these insects. As
the white fly larvre attach themselves to the under side
of the leaves the honey dew.exuded by them falls to the
top side of the leaves beneath, thus affording favorable


J an. 15, 1906.






opportunity for the growth of the fungus. So constant
is the association of the fungus and the white fly that
badly infested groves and hedges may be recognized at
some distance by the heavily coated dark foliage. The
fungus develops on the fruit as well as on the leaves and
stems, and washing becomes necessary, resulting not only
in an added expense, but also in increased danger of
decay in shipping.
In this connection the habits of the tree snail,
Buliimulus Dornt ni, are of the greatest interest. This
snail has been found in the orange groves in Manatee
county feeding upon the sooty mold. Just how long the
snail has been present on orange trees in this county it
is impossible to say It was observed as long as two years
ago by Mr. F. D. Waite at Palmetto. It seems to have
been present in small numbers in other groves' at this
time, but attracted no further attention until the present
summer. The snail is now widely distributed in Mana-
tee county, occurring in many groves on both sides of the
Manatee river. The work of the snails is very character-
istic. When well started they occur in great numbers on
the tree spreading over it from base to top. Its favorite
food seems to be the sooty mold. The fungus is cleaned
from the leaves, stems, and fruit. The leaves thus clean-
ed have a glossy, shiny appearance as though free from
white fly. The fruit thus cleaned has a better color and
probably ripens earlier. In addition to the fungus, the
snail takes algoe and some lichens from the stem and
trunk, giving the trunk a much cleaner and fresher look.
The trees that are cleaned stand out conspicuously from
the surrounding trees by their bright foliage and clean
trunks. The snails increase rapidly under favorable
conditions. The eggs are probably deposited in protect-
ed places about the trunks of the trees, possibly also
about the base of the tree under leaves and other rubbish.
That the snails are capable of doing effective work when
present in sufficient numbers has been shown in numer-






ous groves in Manatee county during the present summer.
Such trees in these groves as are well stocked with the
snails have been thoroughly cleaned, the fruit not requir-
ing washing.
The snails are of medium size, measuring when full
grown three-fourths to one inch in length. The shells
are smooth, white,or corneous white, and with about four
bands of brown spots. Old shells have often a somewhat
coroded surface, the bands becoming indistinct or absent.
When the conditions are unfavorable, either cold or dry,
the snails take refuge in the hollows of the trees or under
leaves accumulated in the forks, or elsewhere, or under
sacks at the base of the trees when these are provided.
It thus becomes an easy matter to transfer them from
tree to tree. A few snails placed by Mr. Wade Harrison
in one of his trees in March, increased in such numbers
as to free the tree of sooty mold by mid-summer of the
same year. The snails are known to range with some va-
riation from the mouth of the St. Johns river on the
north, to the Caloosahatchie river on the south. The
species is probably native td Florida, as specimens in
small numbers were observed about the hammocks and
elsewhere as long as fifty years ago. Its habit of feeding
on the sooty mold of the orange, however, was not known
until within the past two years.
In view of the fondness of the snails for the injurious
sooty mold fungus, it become- of first importance to ob-
serve their treatment of the beneficial fungi. Among the
fungi parasitic on orange insects there are four species of
inestimable value to orange growers. These are, the
brown fungus well known as an effective parasite on the
white fly larve; the red-pink fungus, also parasitic on
the white fly; the red fungus, and the gray headed fun-
gus, both parasitic on the common scales. The brown
fungus so effective in control of the white fly, as is well
known, throws out spreading hyphme for some distance
around the body of the dead larvae. It seems that the






*snails occasionally feed to a limited extent on these
spreading hyphte, but evidently not enough to interfere
with the spread of the fungus, since this fungus is doing
particularly effective work in the groves in the Manatee
region where the snails occur. The red-pink fungus is
also abundant in the groves where the snails occur and is
untouched by them. The snails have not been observed
to feed on either the red or the gray fungi parasitic on
the common orange scales, and it is probably that they
have no taste for these parasitic fungi. Colonies of the
snails are being started in parts of the state where the
white fly injury is severe arid where conditions seem favor-
able for the growth of the snail. It is desirable that close
attention be given to the habits of the snail, as well as to
means of protecting colonies against unfavorable condi-
tions. A few sacks thrown around the tree seem to afford
a needed protection against unusual cold. It is probable
that sprays can not be used on trees stocked with ,the
snails without injury to the colony, for, although pro-
tected by the shell from the immediate effects, sufficient
spray probably clings to the sooty mold on which they
feed to destroy them. The beneficial parasitic fungi and
the snails may be allowed to work together on unsprayed
trees.
The snail is here spoken of as the Manatee snail
since while recorded as occurring in other parts of the
state it was found working on the orange groves first in
the Manatee region.
WState papers please copy.




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