AGRICULTURAL EXPERIMENT -STATION '

0. E. S I tbrahy. Cop. 2.

CONNECTICUT

NEW HAVEN, CONN

BULLETIN 151, JUNE, 1905.

ENTOMOLOGICAL SERIES, No. 12.

The Chief Injurious Scale-lnsecte of
Connecticut.

Rose scale : twice enlarged.

CONTENTS. page

Officers and Staff of Station 2

Chief Injurious Scale-Insects of Connecticut 3

Unarmored or soft scales : PAGE

Greenhouse Orthezia 4

Pit-making oak scale 4

Elm scale 5

Woolly maple leaf scale 5

Common mealy bug 6

Long spined mealy bug 6

Cottony maple scale 6

Soft scale 7

Apricot scale 8

New York plum scale 8

Terrapin scale 8

Tulip scale q

Hemispherical scale n

Armored scales : page

White elm scale 10

Euonymus scale 10

Scurfy scale 11

Pine leaf scale n

Rose scale ir

Putnam's scale 12

Cherry scale 12

White or oleander scale 12

European fruit scale 13

San Jose scale 13

Elm Aspidiotus 14

Circular or fig scale 14

• Morgan's scale 15

Oyster shell scale 15

Thread scale 16

Chaff scale 16

The Bulletins of this Station are mailed free to citizens of Connec-
ticut who apply for them, and to others as far as the limited editions
permit.

CONNECTICUT AGRICULTURAL EXPERIMENT STATION.

OFFICEES .A-IST-D STAFF.

BOARD OF CONTROL.

His Excellency, Henry Roberts, Ex officio,, President.

Prof. W. O. Atwater Middletown.

Prof. W. H. Brewer, Secretary New Haven.

B. W. Collins Meriden.

T. S. Gold West Cornwall.

Edwin Hoyt New Canaan.

J. H. Webb Hamden.

E. H. Jenkins, Director and Treasurer New Haven.

STATION STAFF.

Chemists.

Analytical Laboratory.

A. L. Winton, Ph.D., Chemist in charge.

E. Monroe Bailey, Ph.B. I. A. Andrew, Ph.B.

Kate G. Barber, B.S.

Laboratory for the Study of Proteids.
T. B. Osborne, Ph.D., Chemist in charge. I. F. Harris, M.S.

Botanist.
G. P. Clinton, S.D.

Entomologist.
W. E. Britton, Ph.D.

Assistant to the Entomologist.
B. H. Walden, BAgr.

Forester.
Austin F. Hawes, M.F.

Grass Gardener.
James B. Olcott, South Manchester.

Stenographers and Clerks.

Miss V. E. Cole.
Miss L. M. Brautlecht.

In charge of Buildings and Grounds.
William Veitch.

Laboratory Helper.
Hugo Lange.

Sampling Agent.
V. L. Churchill, New Haven.

The Chief Injurious Scale-Insects of
Connecticut.

By W. E. Britton.

The terms "scale," "scale-insect'' and "bark-louse" are com-
monly used to designate insects belonging to the family Coccidae
of the order Homoptera. The Homoptera are often included
in the Hemiptera, to which belong the true bugs, aphids or
plant-lice, and leaf-hoppers. These insects all suck their food,
and many of them cause serious injury to cultivated plants.
The Hemiptera have incomplete transformations, and the
Coccidae are probably the most degraded of the Hemiptera.
The males are said to have complete transformations, but pos-
sess only two wings in the adult state. Soon after birth the
young crawl about for a few hours ; otherwise the females are
without means of locomotion except in a few species, and are
attached to the bark or foliage of trees and plants, from which
they suck out the sap for food. Some of our worst pests are
scale-insects. The object of this bulletin is to illustrate and
describe briefly the more important kinds occurring in Con-
necticut, so that people will be able to recognize them more
readily and combat them more successfully.

As some of these insects secrete a substance which forms a
shell or covering for protection, they are called armored scales.
Other kinds not forming shells are known as unarmored or soft
scales. Most of the unarmored scales secrete honey dew like
the plant-lice.

The Latin names and arrangement of the following species
are the same as given in Mrs. Fernald's Catalogue of the
Coccidae of the World. The illustrations are all original, and
show the insects natural size except where otherwise indicated.
Figure 5 is from a drawing. All others are from photographs.

CONNECTICUT EXPERIMENT STATION, BULLETIN 151.

UNARMORED OR SOFT SCALES.

1. THE GREENHOUSE ORTHEZIA.— Orthesia insignis Dougl.

This insect is not fixed,
but crawls about like the
mealy bugs, and is shown
in Figure I. Full-grown
specimens are about 1.5 mm
long. It attacks a great
variety of greenhouse
plants, Lantana and Coleus
being favorites. The treat-
ment used against mealy
bugs is advised against this
insect. All breed continu-
ously in greenhouses, and

,^ ., . there are probably many

Fig. 1. The greenhouse Orthezia on c J . J

Lantana leaf. Twice natural size. generations each year.

2. PIT-MAKING OAK SCALE-

Asterolecanium variolosum
Ratz.

This scale is circular, usually greenish-
yellow in color, and has a glassy appear-
ance. It forms a pit or depression in
the bark where it is situated, and it is
about 2 mm in diameter. (See Figure
2.) This species has been sent to the
Station several times on English oak,
Quercus robtir, though it is known to
attack other oaks. Kerosene emulsion
and whale oil soap have been used as a
spray with good results in destroying
this insect.

Fig. 2.
Pit-making oak scale.

UNARMORED SCALES.

3. ELM SCALE — Gossyparia spuria Modeer.

A dark-colored oval scale margined by a white cottony
fringe is not uncommon upon elm trees about New Haven.
It seems to prefer small trees,
but is sometimes found on the
lower branches of medium
sized and large trees. The
insect is about 3 mm long,
brown or black surrounded
by a fringe of white wax, and
is shown in Figure 3. The
young are born alive, appear-
ing about the middle of June
in Connecticut, and settle
along the veins of the leaves
chiefly on the under sides.
Later in the season they re-
turn to the larger branches
and trunk, and occupy the
crevices of the bark, where
they remain through the win-
ter. There is but one brood
each year. Honey dew is
given off profusely by the nearly mature females, and often
drips upon the ground. The scales are readily destroyed at
any time of the year by spraying with kerosene emulsion or
soap and water.

4. WOOLLY MAPLE LEAF SCALE — Phenacoccus acericola

King.
White powdery masses of wax 6 or 7 mm long are frequently
seen on the under sides of leaves of the sugar maple. The
waxy mass contains the mature female (often dead) and a large
number of eggs. The young remain on the leaves until winter
approaches, when they go into the crevices of the rough bark of
the trunk and larger limbs, where they make a sort of nest by
lining the crevices with wax. They remain here until May.
The white oval cocoons of the males are often abundant on the
bark. There are three generations each year. The insect has
been collected at New Haven and South Norwalk, but doubt-
less occurs elsewhere in the state. Very little seems to be
known about remedies for this insect, but probably kerosene
emulsion will prove effective.

Fig. 3. Elm scale.

CONNECTICUT EXPERIMENT STATION, BULLETIN 151.

5. COMMON MEALY BUG— Pseudoco ecus citri Risso.

The mealy bug- is a common pest of plants in greenhouses
and dwellings and even out of doors in summer. Unlike

most scales, the mealy bugs
are not fixed to their food
plants, but are able to move
about, and they attack nearly
all kinds of plants. The full-
grown females are about 4 mm
long and oval in shape. They
are creamy or dirty white,
and covered with a wax secre-
tion which gives them a mealy
appearance. They usually
congregate in the crotches
and at the axils of the leaves
so as to be somewhat pro-
tected. The illustration, Fig-
ure 4, shows them gathered
along the mid-vein of a leaf.
Spraying with soap and water
or fir tree oil or dipping the
plants in the mixture is the
remedy, but hydrocyanic acid
gas fumigation is doubtless
the most satisfactory for greenhouses.

Fig. 4.

Common mealy bug on
oleander.

6. LONG SPINED MEALY BTJG — Pseudococcus longispinus

Targ.

Resembles the preceding, except that the adults bear fila-
mentous appendages at the posterior end of the body. The

species is well distributed.

7. COTTONY MAPLE SCALE— Pulvinaria innumerabilis Rathv.

This scale can be recognized during early summer by the
large white egg-masses on the twigs. Nearly all maples as
well as many other trees are attacked, but the insect seems to
prefer the silver maple. It is not as yet a very serious pest in

UNARMORED SCALES.

>**

Connecticut, but in Chicago, Denver, and some other Western
cities the maples are being seriously injured by it, and extensive
spraying is practiced. There is one annual brood, with eggs
laid in May and June which hatch in July and August. The
young first settle on the leaves. The ;:

males appear in early fall and mate
with the females, which migrate to
the twigs, where they remain through
the winter. In the spring they in-
crease rapidly in size, and soon
deposit their egg-masses and shrivel
and die. The brown female with
white egg-mass protruding posteri-
orly is about 12 mm {% inch) long,
and is shown in Figure 5. The
species is abundantly attacked by
insect parasites.

Kerosene emulsion is used as a
remedy.

A closely allied species, P. aceri-

cola Walsh & Rilev, doubtless occurs FlG; 5- Cottony maple scale ;

females and egg-masses.
here, but the writer has not observed

it. It seems to be confined almost exclusively to the silver
maple, and the egg-masses are laid on the leaves instead of
the twigs. This requires two migrations, — from the leaves to
the twigs in fall, and from twigs to the new leaves in spring.
The females with egg-masses are about /2 inch long, the egg-
mass tapering backward, with four longitudinal ridges.

8. SOFT SCALE— Coccus hcsperidum Linn.

Much has been written about this scale, which was formerly
placed in the genus Lecanium. It is an oval, slightly convex
brown species commonly found on citrus trees, oleanders and
many other plants in greenhouses. Females are viviparous, but
the generations are not well marked. Soap and water or kero-
sene emulsion will readily destroy these scales at any season of
the year.

8

CONNECTICUT EXPERIMENT STATION, BULLETIN 151.

9. APRICOT SCALE — Eulecanium armeniacum Craw.

During- recent years this species has become common out of
doors in Connecticut, and a wide range of plants are attacked.

We have observed it on plum,
grape, chestnut, ash and rose. It
is oval in shape, about 4 mm long,
strongly convex, and light or dark
brown in color. Figure 6 gives a
good idea of its appearance. This
scale is sufficiently abundant to "?
cause considerable injury, and
remedial measures must be taken
<j,gainst , it. There is one brood
annually," the eggs hatch about July
1 st, and the scale winters in a par-
tially gro^vn condition. Spraying
^Jtn winter.* ^itfcr kerosene emufteion
has been successful, but where orchards are treated wiffi3*FiMer ;
and sulphur washes for the San Jose scale, no other treatment
need be given. *'-

Fig. 6. Apricot scale on plum;

immature scales at left,

old shells at right.

10. NEW YORK PLUM SCALE — Eulecanium cerasifex Fitch.

Plum twigs thoroughly infested with this
scale were received from Berlin in 1904.
Superficially it looks like E. armeniacum,
which is shown in Figure 6. The writer
has made no observations regarding its life
history. Where it occurs the same treat-
ment advised for armeniacum should be
employed.

11. TERRAPIN SCALE— Eulecanium
nigrofasciatum Perg.

The writer has several times collected
this scale from the twigs of silver maple,
though it is known to infest fruit and other
trees. The females are smaller than in any
other species of the genus mentioned in
this bulletin. The adult female is of a red-
dish color spotted with dark red or black,

Fig. 7. Terrapin scale
on silver maple.

UNARMORED SCALES. O

2 mm long", convex, with about twelve radiating" ridges, most
conspicuous near the margin. There is probably one brood
each year, eggs being formed in May and hatching in July.
(See Figure 7.)

12. TULIP SCALE — Eulecanium tulipiferae Cook.

This scale is becoming quite common on wild and cultivated

It is the largest of all the
females often reaching a
or I3 of an inch. The
smaller and more elon-
grey pupa skins remain
adult males have emerged,
shown in Figure 8. Ap-
one brood each year, the

tulip trees throughout the state.
brown scales, the hemispherical
diameter of 8 mm,
male scales are much
gated. The light
on the bark after the
Both sexes are
parently there is but

Fig. 8. Tulip scale on tulip tree. Large females are shown above,
and small male shells on lower twig.

viviparous females producing young about September 1st.
They are partially grown when winter sets in. As a rule the
lower branches are first attacked, and often killed, when those
next higher will in turn become infested. Linden and magno-
lia are also attacked by this scale. Kerosene emulsion, and
soap and water applied in the form of a spray, in autumn, are
the common remedies.

13. HEMISPHERICAL SCALE — Saissetia hemispkaerica Targ.

This is probably the most common of all the large brown
scales found in greenhouses and dwellings. It has a long list
of food plants, and may be expected to attack almost any kind

IO CONNECTICUT EXPERIMENT STATION, BULLETIN 151.

of plant, but chiefly palms, ferns, Cycas and orchids. It is
from 3 to 4 mm long', and reddish or dark brown in color.

Specimens
are found on
both leaves
and stems.
(See Figure
9.) It prob-

fably breeds
continuously
throughout
the year.
Kerosene
. emulsion, fir

tree oil and
soap and
water can be
used as sprays
and green-
houses can be
fumigated
with hydro-
cyanic acid
gas to destroy

this insect.
Fig. 9. Hemispherical scale on fern.

ARMORED SCALES.

14. WHITE ELM SCALE—

Ch ionaspis americana
Johnson.
This scale attacks the twigs
of the elm, and closely resem-
bles the scurfy scale, shown
in Figure 1 1 . It is not very
abundant in Connecticut.

15. ETJONYMTJS SCALE—
Chionaspis euonymi Comst.
This species was recently

sent to the writer from -Hart- Fig. io. Euonymus scale on Euony-

i^~A „,u^~~ ;<- ,,,„„ nU-.^An^t. mus radicans. The white shells are
lord, where it was abundant f . , , , ,

' males. A few larger grey females

on Euonymus radicans along are present.

ARMORED SCALES.

a brick wall. The wall was covered with canvas, and the plants
fumigated with hydrocyanic gas.

The euonymus scale resembles the scurfy scale, but the
females are somewhat smaller and darker in color. It passes
the winter in the egg stage, and the different species of Euony-
mus and the orange are attacked. It is shown in Figure 10.

16. SCURFY SCALE— Chionaspis furfnra Fitch.

The female shell is broadly pyriform,
3 mm in length, and white or light grey.
See Figure 1 1 . The male is much smaller,
white, with sides parallel, and three
ridges along the back. A single brood
is formed each year, and the winter is
passed in the egg stage. These eggs
are oval in shape, purple in color, and
hatch between May 20th and June 1st.
Spraying with soap and water or kero-
sene emulsion soon after the eggs hatch
will readily destroy the young. For a
more complete history of this insect the
reader is referred to Bulletin No. 143

Fig. 11. Scurfy scale on or the Report of this Station for 1903,
currant ; males at left,
females at right. page 227.

17. PINE LEAP SCALE— Chionaspis pinifoliac Fitch.

Resembles the preceding, but is attached to
the leaves or " needles " of the pine, spruce
and other coniferous trees. It has been collected
at South Manchester on Pinus mughus. There
are two broods each year, and the winter is
passed in the egg stage. See Figure 12.

18. ROSE SCALE— Aulacaspis rosac Bouche.

A large white scale is sometimes seen on rose
bushes, raspberry or blackberry canes, especially
where growing in crowded rows or clumps.
The female is nearly circular, 2.5 mm in diam-
eter, and is shown on the cover of this bulletin.
The male is much smaller, long and narrowr, with

Fig. 12.
Pine leaf scale.
Enlarged about

twice.

12 CONNECTICUT EXPERIMENT STATION, BULLETIN 151.

three parallel ridges running lengthwise of the shell. Professor
John B. Smith of New Jersey has studied this scale recently,
and finds that all stages from the egg to the mature female
occur at the same time during the winter and throughout the
season. Probably there are but three complete broods, but
these overlap so that breeding is almost continuous.

As all stages of the insect occur at the same time remedial
treatment is somewhat difficult, as the eggs are usually not
killed by sprays, and sometimes survive even fumigation. The
worst infested canes should be cut out and burned. Kerosene
emulsion or soap and water should be used as a summer spray,
and the lime and sulphur mixture may be applied to the dormant
plants in winter.

19. PUTNAM'S SCALE— Aspidiotus ancylus Putnam.

This is a small circular scale, 2 mm in diameter, which occurs
throughout the state on fruit trees, but perhaps most frequently
upon currants, often killing the second year canes or shoots.
The shells of this scale are usually not as nearly circular as the
San Jose scale, but it is often difficult to distinguish them in
the field. Apparently there is but one brood each year.

20. CHERRY SCALE — Aspidiotus forbesi Johnson.

This scale closely resembles the preceding, and though not so
widely distributed, has been found upon fruit trees in Con-
necticut. It should be regarded as a serious enemy, and treated
in the same way as the San Jose scale.

21. WHITE SCALE; OLEAN-
DER SCALE— Aspidi-
otus hederae Vail.

This scale is a pest of green-
houses, where it attacks olean-
der, croton, ivy, palms, camel-
lia and many other plants. It
is nearly circular in shape,
and white or light grey in
color, making it conspicuous
on the green leaves and stems.
(See Figure 13.) It probably

t, W1 , , , breeds continuously in green-

riG. 13. White or oleander scale .

on Croton leaf. houses. Fumigating the

ARMORED SCALES. 1 3

house with hydrocyanic acid gas, spraying" the infested plants
with either whale oil or common soap (i lb. in 8 gallons of
water) are the remedies for this scale.

22. EUROPEAN FRUIT SCALE — Aspidiotus ostraeformis

Curtis.

This scale is not known to be established in Connecticut, but
will doubtless become so, as it has been found on nursery trees
sent into the state. It looks very much like the cherry, Put-
nam's, and San Jose scales, and can be distinguished from
them only by means of the compound microscope. In fact
these four species resemble each other so closely that the fruit
grower cannot distinguish between them unless he is an ento-
mologist. The European fruit scale attacks all kinds of orchard
trees, and there is probably a single brood each year.

23. SAN" JOSE SCALE — Aspidiotus pemiciosus Comst.

This is a circular scale, light or dark grey in color, with con-
centric markings and a nipple in the center, which is usually
darker in color than the surrounding portion of the shell. The
winter is passed in a half-grown condition, and there are no
eggs. The breeding season begins soon after June 20 and ends
about December 1 in Connecticut, three or four broods appear-
ing in a season. For a full account of its life history and
spread, see Bulletin No. 135 of this Station.

This scale is the worst pest of the fruit grower in Connecticut,
and attacks all kinds of fruit trees, except the sour cherry
{Primus cerasus) , and many kinds of shade trees and ornamental
shrubs are attacked and sometimes killed. A list of trees and
plants, showing their susceptibility to attack by this scale, was
published in the Report of this Station for 1902, page 130. A
thorough spraying in the fall after the leaves drop, or in the
spring just before the buds start, using a lime and sulphur mix-
ture, seems to be the best remedy for Connecticut. This mixture
is usually prepared by boiling together 20 pounds quicklime and
14 pounds sulphur for 45 to 60 minutes in enough water to keep
it a liquid. After boiling, water should be added to make 40
gallons, and the whole applied at once. Satisfactory mixtures
can be made without boiling by using potassium or sodium sul-
phide, caustic soda or sal soda to aid in dissolving the sulphur.
Some of these mixtures and the proper outfit for spraying are

14 CONNECTICUT EXPERIMENT STATION, BULLETIN 151.

described in Bulletin No. 146, and reproduced in the Report of

this Station for 1904, pages 240-252.

The accompanying" illustration of the San Jose scale ( Fig-
ure 14) will serve to
■ 1 ji^ show the appearance of

the other kinds which so
closely resemble it. All
can be combatted in the
same way, viz: by spray-
ing the dormant orchard
trees with the lime and
sulphur mixture, and by

fumigating nursery stock with hydrocyanic acid gas.

Fig. 14.

San Jose scale on peach twij
Twice natural size.

24. ELM ASIPIDIOTTJS—Aspidiotus ulmi Johns.'

This is a small circular scale resembling the preceding, which
is found on the smooth or inner bark in the crevices of the
rough bark of the trunks and larger branches of elm trees. It
seems to do very little damage, but may be found on most of
the elm trees of New Haven, and doubtless occurs throughout
the state.

25. CIRCULAR SCALE : FIG SCALE— Chrysomphalus aonidum
Linn (ficus Ash.).

Fig. 15. Circular or fig scale on rubber plant.

Rubber plant, orange, palms, camellias and oleander in
greenhouses are often infested by a round dark-colored scale
which stands out prominently from the surface of the leaves.

ARMORED SCALES. I 5

In fact it is almost conical in shape, reddish brown or nearly
black, with an orange apex, and is shown in Figure 15. Pre-
sumably it continues to breed throughout the year under glass,
and continued spraying is necessary to keep it in check.

26. MORGAN'S SCALE — Chrysomphalus dictyospermi Morg.

This species is a serious pest of palms at Pierson's large com-
mercial greenhouses, Cromwell, and it has also been taken in
private plant houses in other parts of the state. It is of about
the same color as the preceding species, but is flatter, and pro-
jects only slightly from the leaf. Mr. H. E. Hodgkiss studied
this scale at the Massachusetts Agricultural College, and found
that several generations are produced each year, but these over-
lap so as to become indistinct. The females bring forth living
young, are parthenogenetic, and males are unknown. Fumi-
gating the house with hydrocyanic acid gas, using 7.5 grams
potassium cyanide for each 100 cubic feet of space, for forty
minutes, after dark, with the plants free from moisture, is the
treatment advised by Mr. Hodgkiss after making many experi-
ments. It is probably a safe remedy for nearly all of the
greenhouse scales.

27. OYSTER SHELL SCALE— Lepidosaphes uhni Linn
(formerly Mytilaspis pomorum Bouche).

One of the most common and widely distributed of all
coccids. It is a pest of fruit trees, especially apple, and many
young sprouts and seedlings of birch, poplar, willow, ash and
butternut are killed by it each year. Lilac is also infested.
There is but one brood annually,
and the insect winters in the form
of oval white eggs under the female
shells. The eggs hatch in Connec-
ticut about the first of June, the
young, crawl for a few hours, then
settle upon the bark and form
shells, becoming mature in Septem- FlG- l6- °3'ste[ she11 scale

' & on poplar.

ber. Eggs are laid about the first

of October, and the females die. The female scale (or shell),
is from 2 to 3 mm long, about the same color as the bark upon
which it rests, elongated pyriform in shape, and more or less
curved. It is shown in Figure 16. Male shells are much

1 6 CONNECTICUT EXPERIMENT STATION, BULLETIN 1 51.

smaller and less curved than those of the female. The adult
male has two wings, and is seldom seen. Spraying with kero-
sene emulsion or soap and water soon after the eggs hatch will
hold this scale in check. For a more complete account see
Bulleton 143, or the Report of this Station for 1903, page 229.

28. THREAD SCALE — Ischnaspis longirostris Sign.

This is a long narrow black scale attacking palms, pandanus
and many other plants in greenhouses. It has been taken in
Connecticut only at one greenhouse in New Haven, where it

Fig. 17. Thread scale on palm leaf.

was quite abundant. Little is known of its life history, and the
male is unknown. The female shell is from 2 to 3 mm long,
and about eight times as long as broad, and more or less
curved. (See Figure 17.) The writer has had no experience
in combating this scale, but the same treatment used for other
greenhouse scales will doubtless hold it in check.

29. CHAFF SCALE — Parlatoria pergandii Comstock.

This is common on various greenhouse plants, especially
orange and lemon. It is oval in shape, with the molted skin at
one end, and is light yellow in color. It is usually found in
clusters. The common sprays used for greenhouse scales seem
to be effective against this species.

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