Table Of ContentTHE BIOLOGY AND CONTROL OF THE SCURFY
SCALE /CHIONASPIS FUHFURA (FITCHjJ ON APPLES IN VIRGINIA
Dissertation
Presented in Partjial Fulfillment of the Requirements
for the Degrefl| Doctor of Philosophy in the
Graduate School of The Ohio State
University
By
Clarence Howell Hill, B.S., M.S.
4 •
The Otjio State University
1951
Approved by:
Adviser
CONTENTS
Pag*
Acknowledgments................................. ii
Introduction. . ................................ 1
Review of Literature.............................. 2
Economic Importance .............................. 3
Nature and Extent of Injury ..................... 6
Dissemination .................................... 3
Methods and Technique ............................ 9
Life History.................................. 16
First generation........................ 16
Second generation........................ 34
The male................................... 36
Male behavior and longevity.............. 44
Fertilisation............................ 45
Sex ratio................................ 49
Eggs deposited per female................ 49
Number of generations....................... 52
Natural Enemies ................................. 52
Control......................................... 57
Description of Materials........................ 62
Summary......................................... 64
Literature Cited.............................. 67
Autobiography ................................... 70
*
1
892517
ACKNOWLED GMKNTS
This study was made at the suggestion and under the
supervision of Dr. W. S. Hough, entomologist, Winchester
Research Laboratory, Virginia Agricultural Experiment
Station, Winchester, Virginia. Dr. Hough advised and aided
in the planning and execution of experiments and procedures.
He also read and criticized this manuscript. The author is
also indebted to Dr. Alvah Peterson, professor of entomology,
The Ohio State University, Columbus, Ohio, for much valu
able instruction and advice in connection with this study.
Determinations of the parasites and the predacious mite
were made by the Division of Insect Identification, Bureau
of Entomology and Plant quarantine, U. S. Department of
Agriculture. The Aphytis species were determined by Mr.
A. B. Gahan and the Hemisarcoptes malus by Dr. E. W. Baker.
Dr. A. B. Groves, plant pathologist, Winchester Research
Laboratory, did the photography. The statistical analyses
were made by the Department of Statistics, Virginia Poly
technic Institute, Blacksburg, Virginia. The arrangement
of plots and methods of collection of data were arrived at
through consultation with Dr. Boyd Harshbarger, head of
the Department of Statistics. The Virginia Agricultural
Experiment Station provided the funds, equipment, and most
of the materials necessary for this study. Thanks are due
ii
to Mrs. Beckmann, secretary,; for assistance with and typing
the manuscript. The author gratefully acknowledges the
assistance of all of these people.
iii
THE BIOLOGY AND CONTROL OF THE SCURFY
SCALE /CHIONASPIS FURFURA (FITCHJJ ON APPLES IN VIRGINIA
INTRODUCTION
Scurfy scale is a serious pest in many orchards and a
threat to most apple orchards in Virginia. This scale
insect not only weakens the tree, but will kill the lower
branches and eventually the tree itself. In addition, the
fruit frequently becomes infested and is thereby barred
from the quality fruit market.
Since the life history and habits of scurfy scale have
been meagerly described in the literature, and the oil
sprays usually recommended for scale insect control are
frequently accompanied with excessive oil injury to the
buds, it was felt that an investigation of the life history
and exploration of non-oil materials to control scurfy
scale was not only warranted but highly desirable. In the
spring of 1947 the writer started a study of scurfy scale
on apple, emphasizing the little-known aspects of its life
history and control measures, especially the use of new
materials that would be feasible in a control program.
1
2
REVIEW OF LITERATURE
Scurfy scale injury on apple and pear trees in
Massachusetts was first reported in 1341 by T. W. Harris
(4) in his "Insects Injurious to Vegetation." Harris did
not name the pest. In 1356, Asa Fitch (4), state entomolo
gist of New York, described this scale as Aspldiotus
furfurus and reported its occurrence and injury on apple
and pear in New York State.
Later, a number of writers from many parts of the
United States reported this scale insect as occurring on a
variety of host plants. In general, these early writers
gave a description of the scale insect, also treated its
taxonomy, hosts, and distribution. Among the entomologists
who gave detailed descriptions of the scale were Comstock,
1381; Cooley, 1899; Felt, 1901; Sanders, 1904; Johannsen,
1912; Fernald, 1913; Dietz and Morrison, 1916; Lawson, 1917;
and Ferris, 1937.
Quaintance and Sasscer, 1916, made a complete list of
infested host plants and distribution of the pest from
available publications and from data collected by the
Bureau of Entomology and Plant quarantine. These authors
also presented a brief life history and included the
reported parasites and predators as well as recommendations
for control. Hough, 1932, and Aull and Dean, 1933> evalu
ated the efficiency of various concentrations of lubricating
3
oil and tar oil emulsions when used as dormant sprays
against scurfy scale* Hough, 1932, briefly described the
life history of this scale insect in northern Virginia*
Hammer, 1933, 1942, and Brann, 1944, investigated further
the efficiency of oil and tar oil sprays in control of this
scale. These authors also treated the life history in
New York State. Hough, 1939, and Hammer, 1933 and 1942,
found that the addition of dinitro-o-cyclo-hexylphenol
increased the efficiency of dormant oil sprays.
ECONOMIC IMPORTANCE
Scurfy scale is widely distributed over the United
States. Quaintance and Sasscer, 1916, state that this
scale insect has been reported from California, Colorado,
Connecticut, Delaware, District of Columbia, Georgia,
Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine,
Maryland, Massachusetts, Michigan, Minnesota, Mississippi,
Missouri, Nebraska, New Hampshire, New Jersey, New York,
North Carolina, Ohio, Pennsylvania, Rhode Island, South
Carolina, South Dakota, Tennessee, Utah, Virginia, Washing
ton, West Virginia, and Wisconsin. In Canada it has been
reported from New Brunswick, Nova Scotia, Ontario, and
Prince Edward Island. Lyne, 1933, reported this scale
insect on maple arriving from Japan.
Scurfy scale has been reported from a long list of
4
host plants. jualntance and Sasscer, 1916, compiled a list
of all plants on which this species had been reported.
Their list is as follows:
Apple (Malus sylvestris Miller)•
Apple, Chinese flowering (Malus spectabilis Ait.).
Apple, crab (Malus sp.).
Ash, European mountain (Sorbus aucuparia Linn.).
Ash, mountain (Sorbus americana Ait.).
Ash, prickly (Xanthoxvlon americanurn Mill.).
Ash, white (Fraxinus americana Linn.).
Aspen, largetooth (Populus grandidentata Michx.).
Buckthorn (Rhamnus cathartica Linn,).
Cherry, choke (Prunus virginiana Linn.).
Cherry, wild black (Prunus serotina Ehrh.).
Cherry, wild red (Prunus pennsvlvanica Linn.).
Chokeberry, black (Aronia melanocarpa ^ i c h x ^ Elliott).
Chokeberry, red (Aronia arbutifolia Pers.).
"Cherry currant".
Cotton (Gossvpium sp.)
Currant, black (Kibes nigrum).
Currant, red flowered (Ribes sanguineum Pursh.), England
Elm (Ulmus sp.).
Gooseberry (Ribes sp.).
Hawthorn (Crataegus oxvacantha Linn.)•
Hickory, big bud (Hicorla alba Britt.).
5
Horse chestnut (Aesculus hippocastanum Linn.).
Maple (Acer sp.).
Peach (Amvgdalus persica L.).
Pear (Pyrus communis Linn.), (P. heterophylla Dur.)
(P. melanocarpa).
Plum, purple-leaved (Prunus pissardii Hort.).
Plum, common garden (Prunus domestica Linn.).
quince (Cydonia vulgaris Pers.).
quince, Japan (Chaenomeles .laponica /Thunb^ Lindl.).
Raspberry, black cap (Rubus occidentalis Pers.).
Red-twigged dogwood (doubtful record).
Shad-bush (Amelanchler canadensis Medic.),
Sweet gum (Liouidambar stvraciflua).
Sweet pepper bush (Clethra alnxfolia Linn.).
Valnut, black (Juglans nigra Linn.).
Willow, white (Salix alba Linn.).
To this list may be added cotoneaster reported from
California by Hewitt, 1940. Apple and pear are the most
common hosts. However, cnerry, peach, raspberry, and
currant are also infested. Flint, et al., 1933» state that
this scale insect was found in almost every raspberry
plantation during a survey of the crop in southern Illinois.
Apple is the most important host in Virginia. In
northern Virginia, the author has observed scurfy scale in
a large number of orchards. Many of these infestations were
6
heavy enough to cause serious injury; in some cases trees
were killed. Heavy infestations have been observed on the
following apple varieties: Grimes Golden, Stayman, Golden
Delicious, York Imperial, Black Twig, Red Delicious, Ben
Davis, Gano, and King David.
The author has not observed this scale on any host
except apple, although he carefully examined many probable
species that were growing in the vicinity of heavily
infested apple orchards.
NATURE AND EXTENT OF INJURY
Heaviest infestations usually occur on the trunks and
lower branches of apple trees. The undersides of the limbs
are generally more heavily infested than the upper sides.
The first generation starts on the old wood. Second gene
ration scale insects may, and in heavy infestations always
do, move onto the new growth, fruit, and leaves, in addition
to infesting the old wood. A light infestation may produce
no observable injury to the apple tree. When the infes
tation becomes heavier, the vigor of the tree is obviously
reduced. Eventually the lower limbs start to die. If left
unchecked (see figure 1), the infestation will progress
until the entire tree dies.
