JOURNAL OF ECONOMIC ENTOMOLOGY 
522 
[Vol. 16 
THE WHITE SNAIL {HELIX PISAN A) AT LA JOLLA, CALIFORNIA 
By A. J. Basinger, University of Californiaf Citrus Experiment Station 
Abstract 
Helix pisana, a European snail, became established in California and measures 
were taken to eradicate it. In Europe this snail is a pest of citrus trees. Observa¬ 
tions at La Jolla, California, verified this. It is also a possible pest among other 
cultivated plants. The average number of eggs per individual at La Jolla in De¬ 
cember 1922, was 120. This is higher than the number given for Europe. The 
methods employed in eradication were; clearing the ground of vegetation, flaming 
the cleared areas, use of poison bait of calcium arsenate and bran, and hand-picking. 
The results were effective and very few Helix pisana are left after one year of eradi¬ 
cation work. - 
The white snail {Helix pisana ) is a European species, native in Sicily 
and of considerable economic importance in that country as a pest of 
orange and lemon trees. The fact that this snail had gained a foothold 
at La Jolla, San Diego County, California was first brought to the at¬ 
tention of California horticultural officials by Dr. L. O. Howard in 1918. 
Eradication measures were undertaken at that time which resulted in 
almost complete extermination (1). Inability, however, to keep up 
the fight against the snails resulted within a few years in an infestation 
of such magnitude that there was grave danger of the white snail spread¬ 
ing to the citrus areas of California. The Bureau of Pest Control of 
the California State Department of Agriculture and the San Diego County 
Horticultural office, in consultation with the U. S. Department of Agri¬ 
culture then formulated a cooperative campaign to eradicate the pest. 
Active operations were commenced on July 17, 1922. 
Economic Status of Helix Pisana 
The economic importance of Helix pisana in Europe is given by 
.T. de Stefani (2). He says that the snails feed on the foliage, bark, 
tender twigs,, fruit and blossoms of orange and lemon trees, and on the 
foliage of almond and olive trees. In La Jolla pisana was observed to feed 
on a great variety of plants, including a small grapefruit tree that was 
seriously impaired by constant defoliation. In another instance a clump 
of zinnias in a flower garden made no progress until the snails were 
destroyed on the premises. The fact that Helix pisana feeds voraciously 
on a variety of plants indicates that it may be a possible pest of crops 
other than citrus. I have no doubt that it would prove quite damaging 
to vegetable crops and small fruits as I found it to be fond of the leaves 
of sweet potatoes, chard, beets and blackberries. 
As a nuisance this snail has first rank about a home because it occurs 
in enormous numbers where conditions are favorable and crawls on and 
x This paper records the results of work undertaken while the writer was in the 
employ of the California State Department of Agriculture. 
