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AGRICULTURAL EXPERIMENT STATION

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NEW HAVEN, CONN.

BULLETIN 143, MAY, 1903.

ENTOMOLOGICAL SERIES, No. 9-

Two Common Scalc-lnsccts of the Orchard.

The Scurfy Bark-Louse. The Oyster-Shell Bark-Louse.

CONTENTS.

Officers and Staff of Station

Two Common Scale-Insects of the Orchard.

The Scurfy Bark-Louse ....

The 03'ster-Shell Bark-Louse

Remedies

Summary

p C E I V F n

4 1903

U.S. Dep&»tmento1 Agriculture.

Paare.

The Bulletins of this Station are mailed free to all citizens of Connecticut who apply for them, and to others as far as the limited editions permit

CONNECTICUT AGRIGDLTURAL EIPERIMENT STATION,

BOARD OF CONTROL.

Ex officio. His Excellency Abiram Chamberlain, 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.B., Chemist in charge.

A. W. Ogden, Ph.B. M. Silverman, Ph.B.

E. Monroe Bailey, Ph.B.

Laboratory for the Study of Proteids.

T. B. Osborne, Ph.D., Chemist in charge.

I. F. Harris, B.S.

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

Entomologist. W. E. Brixton, B.S.

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

In charge of Forestry Work. Walter Mulford, F.E.

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 Helpers. Hugo Lange. William Pokrob.

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

TWO COMMON SCALE-INSECTS. 3

TWO COMMON SCALE-INSECTS OF THE ORCHARD.

The Scurfy Bark-Louse Chionaspis furfurus Fitch. The Oyster-Shell Bark-Louse Mytilaspis poinorum Bouche. By W. E. Britton, State Entomologist.

Long before Connecticut orchards were attacked by the San Jose or pernicious scale-insect, the scurfy bark-louse and the oyster-shell bark-louse were present as parasites upon the trees and caused considerable damage each year. These orchard enemies still injure trees, though their work has been some- what overshadowed by the damage of the San Jose scale dur- ing the last few years. The two kinds of scale-insects described in this publication are frequently received at the Station and the correspondent usually asks if it is the San Jose scale. This bulletin has been prepared for the purpose of dis- tributing information about these two common species and the remedies for them, as well as to point out wherein they differ in appearance from the San Jose scale. The San Jose scale- insect has three or four broods each- year, is circular in outline, and is shown in figure i. The oyster-shell and scurfy bark- lice are much larger, elongated or pear-shaped, and single brooded. See figures 2 and 4.

The life histories of the species forming the subject of this bulletin are so nearly alike that the same remedial treatment answers for both.

The terms "scale" and 'bark-louse" are both applied to insects of this group {Coccidce) and may be considered as synonymous w'ith the compound w'ord "scale-insect."

The Scurfy Bark-Louse.

The scurfy bark-louse is a native of North America, and was formerly called "Harris' Bark-Louse." It is now found throughout the United States, and, according to Howard, is being succeeded by the oyster-shell bark-louse.*

The female scale is about 3 mm. (^ inch) in length, broadly pear-shaped, with the cast larval skin at the smaller

* Year-book, 1S94, U. S. Department of Agriculture, p. 259, Washing- ton, D. C.

4 CONNECTICUT EXPERIMENT STATION, BULLETIN I43.

end which usually points upward. The color is light grey or white. The male scale is much smaller than the female, pure white, with three parallel ridges along the back, and parallel sides. Males and females usually occur on separate twigs. Both sexes are shown in figure 2.

There is only one generation each year in Connecticut. The eggs hatch during the latter part of May. Our records show

Fig. I. — San Jos6 scale on peach twig : a. mature females : b. young females : c. immature males. About twice natural size.

that on May 19th, 1902, material was brought to the Station from North Guilford, and that some of the eggs had hatched. The writer has made observations on this point for several years and usually the eggs hatch here between May 20th and June 1st.

THE SCURFY BARK-LOUSE.

5

The newly-hatched insect (see figure 3, c) crawls about for a short time, then becomes fixed, forms a shell and sucks the sap from the tree. The female becomes mature during Septem- ber, and later dies and shrivels up, leaving the old shell filled with oval, purple eggs. Usually between thirty and fifty eggs are produced by each female. In Connecticut the writer found the eggs as early as October ist in 1900, while they had not been formed on October 9th, 1901. Usually they are formed during the first week in October. Howard states that in the vicinity of Washington the eggs are formed October 15th and hatch uniformly about the middle of May.* There is probably more than one brood in the Southern States.

Fig. 2. — Scurf}' bark-louse : a. c. females : b. d. males . a. b. natural size : c. d. much enlarged. (After Howard, Year-book of U. S. Depart- ment of Agriculture for 1S94.)

The chief injury caused by this species occurs to young pear and apple trees either in nursery rows or in newly-set orchards. Sometimes the bark of the trunk and branches is entirely cov- ered by the grey shells, thus giving the tree the appearance of having been whitewashed. Such trees make little growth and are frequently killed outright. Seldom do we find the insect abundant on large trees. Currant bushes are often infested and mountain ash and hawthorn are frequently attacked by the scurfy bark-louse. The appearance of an infested currant twig is shown on Plate I.

* Loc. cit.

6 connecticut experiment station, bulletin i43.

The Oyster-Shell Bark-Louse.

This insect is well known and occurs all over the world. Europe is thought to be its original home, but it has been known to be present in the United States for over one hundred years. It is more common at the North, where it is single- brooded, than in the South, where two generations occur each year.

Fig. 3. — Scurfy bark-louse : adult male above : b. foot : h. tip of antenna: c. larva : d. antenna of larva : e. leg of larva : f. pupa : g. adult female with armor removed. All greatly enlarged. (After Howard, Year-book of U. S. Department of Agriculture for 1894.)

The armor of the female (shown in figure 4) is about 3 mm. (}i inch) long, narrow and usually somewhat curved, and nearly the same color as the bark upon which it is found. The cast larval skin may be seen at the pointed end. Generally it is darker in color than the scurfy bark-louse, as well as narrower. The armor of the male is much smaller and less curved than that of the female. The male scales are seldom seen upon fruit trees. The adult male (shown in figure 5) is provided with

THE OYSTER-SHELL BARK-LOUSE.

a pair of wings, legs, antennas and eyes, and resembles the male of the scurfy bark-louse.

The oyster-shell bark-louse, like the scurfy bark-louse, passes the winter in the egg stage and the small, oval, white or pale yellow eggs hatch about the first of June or a few days later than the eggs of the scurfy bark-louse. The young were crawling on twigs received at the Station June 9th, 1902. As many as one hundred eggs are sometimes laid by a single female.

Fig. 4. — Oj'ster-shell bark-louse : a. female scale from below showing eggs : b. dorsal view of same : d. male scale — all enlarged : c. females , e. males — natural size on twigs. (After Howard, Year-book of U. S. Depart- ment of Agriculture for 1894.)

No observations have been made by the writer regarding the time when the eggs are laid in the fall, but eggs were formed in specimens collected in December. According to Smith the eggs are formed late in August and during September.*

The oyster-shell bark-louse is found on nearly every old apple tree in Connecticut, and may occur on the small twigs * Bull. 140, New Jersey Exp. Station, p. 5.

CONNECTICUT EXPERIMENT STATION^ BULLETIN I43,

and on the large branches and trunk in the crevices of the rough bark. It weakens trees unquestionably, but the writer has never seen fruit trees killed by the oyster-shell bark-louse in Connecticut. Many seedlings and sprouts of native trees in fields and woods are killed each year by it. Ash, poplar, willow, birch, butternut, black-walnut and maple are the trees most commonly injured, and are frequently infested to such an extent that no portion of the bark can be seen.

Fig. 5. — Oyster-shell bark-louse: a. adult male: b. foot: c. larva; d. antenna of larva : e. adult female with armor removed. All greatly en- larged. (After Howard, Year-book of U. S. Department of Agriculture for 1894.)

In nurseries and ornamental plantations lilac, Kilmarnock willow and some species of Elceagniis are often seriously infested.

The appearance of twigs and branches infested by the oyster-shell bark-louse is shown on Plate II.

Remedies.

The eggs of both the scurfy and the oyster-shell bark-lice are hard to kill, so that winter applications are not effective in

REMEDIES. 9

fighting the species. Some writers advise a winter application of whitewash to destroy them : this frequently causes the shells to fall from the bark and the eggs are scattered, and perhaps to such an extent that the young are not able to reach the tree. But many eggs remain on the tree and are not injured by the whitewash. Frequently these eggs withstand applications of kerosene and crude oil. The most vulnerable point in the life history of both species is just after the eggs hatch, while the young are crawling and before they have become protected by the formation of their shells or armor. In Connecticut this period occurs during the first half of June, and the newly- hatched insects may be destroyed readily by spraying with any of the common contact insecticides. Common soap and water (i lb. dissolved in 8 gallons) is as convenient as any applica- tion and is cheap and efifective. Any laundry soap will answer. It should be cut in thin slices, dissolved in boiling water and diluted to make the proper proportions. Whale-oil soap in the same proportions can also be used. Kerosene emulsion is recommended, and a mechanical mixture of kerosene and water, containing from lo to 15 per cent, of kerosene, applied with a " Kerowater" pump is also a cheap and satisfactory remedy.

Summary.

1. The scurfy bark-louse and the oyster-shell bark-louse have commonly injured fruit trees for many years in Connecti- cut by sucking out the sap and are often mistaken for the San Jose scale-insect, which, on account of a different life-histort, must receive different treatment.

2. The scurfy bark-louse is a native of North America and is well distributed over the United States. The female is light grey and pear-shaped, while the male is much smaller, white with parallel sides. There is one brood each year at the North. It winters in the egg stage and the eggs hatch during the latter part of May. Eggs for the next brood are laid the first week in October. Small apple and pear trees and currant bushes are the most seriously infested and are sometimes killed.

3. The oyster-shell bark-louse is found all over the world, and was probably introduced into this country from Europe more than a hundred years ago. It is darker in color and

10 CONNECTICUT EXPERIMENT STATION, BULLETIN I43.

narrower than the scurfy bark-louse ; the hfe history is very similar, but the eggs are a few days later in hatching, and are formed earlier in the fall. There is one brood each year. It infests apple, but is common on ash, poplar, willow, butternut and lilac, often killing them.

4. Spraying the trees during the first two weeks in June, or while the young are crawling, with soap and water (i lb. in 8 gals.) or with kerosene emulsion will readily destroy the newly- hatched larvae.

PLATE I.

SCURFY BARK-LOUSE Chiouaspis furfurns Fitch. Females on currant. Natural size.

PLATE II.

yV^^:,

OYSTER^SHELL BARK-LOUSE Mylilaspis pomorum Bouclie. Females on poplar. Natural size.

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