Ephraim Porter Felt.

Insects injurious to forest trees online

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NEW YphK

Commissioners of Fisheria?
Came and Forests



Exti-Bct from 4th Annaul
Report. 1898




GIFT OF

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-. 5 SPPlli

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from tl>e



Foartf) Annaat Report

Of tl)C

(Commissioners of fisheries, Ciame

and forests



OP THE



or new



Insect^; Injarioa^ to Forest



B. P. Felt, D. 3c., ^State Entomotocrist.



r



L



from the



Poartl) Annaal Report



of the



of pineries,
and porests



OF THE 3TATE OF NEW



Insect^ Injurious; to Forest Tree^.



Bt

P. Felt, D. 3c., atate Entomologist.




Commissioners of Fisheries, Game and Forests.



Barnet H. Davis, President. . Palmyra, X. Y.

Hendrick S. Holden, Commissioner, .. . . Syracuse, X. V.

William R. Weed, Potsdam. X. \ .

Charles H. Babcock, .... Rochester, N. Y.

Edward Thompson, Northport, I.. I., N. Y.

Charles A. Taylor, Assistant Secretary Albany, X. \'.



/QZ <??/, /



Injarioas to Aaple Trees.

BY E. P. FELT, D. Sc., STATE ENTOMOLOGIST,

UNIVERSITY OF THE STATE OF NEW YORK.

THE conditions under which shade trees are grown vary so widely from those
under which the same trees live in the forest, that methods of controlling
injurious insects found practicable in the one case can not be advised in the
other. For this reason the present paper will be confined to insects affecting shade
trees, and space limitations render it advisable to treat of only a few of the most
injurious species affecting maples. It will be found, however, that most of these
pests attack other shade trees, and that in one instance at least, that of the white
marked tussock moth, the caterpillars prefer the horsechestnut ; but as maples
are the more abundant shade trees throughout the state, even this species is of
greater importance on account of its injuring maples than because it attacks the
horsechestnut.

Transformations. Before treating of individual species, it may be profitable to
glance briefly at the life history of insects and the relation of the various stages to
each other. All insects hatch from eggs, which present widely variable forms in
different species and are frequently of exceedingly beautiful design. In certain cases
the ova or eggs hatch within the body of the parent. Members of the very lowest or
simplest order of insects, such as snow fleas, slides or silver fish and their allies,
undergo no transformation, that is, there is very little difference between the young
and the adults. Among grasshoppers and related insects, there is what is called an
incomplete metamorphosis or transformation. The young grasshopper, as it emerges
from the egg, is a curious, wingless little creature, bearing a general resemblance to
the parent and can easily be recognized as a grasshopper. As the little fellow
increases in size, it casts its skin from time to time and with each molt the wing pads
become longer and in the final change the wing cases are slipped off and the organs
of flight are at liberty to perform their proper functions. In the stage before the final
one, the wing pads may be as long as the fully developed wings, but the two stages
may easily be separated by the position of these organs. In the adult the fore wings
fold over and conceal the hind ones, while in the immature grasshopper the hind wing
pads are outside of the^fore ones. Many insects like cockroaches, walking sticks,
dragon flies, true bugs and others develop in this manner, but not all resemble the
adult so closely in the earlier- stages as do grasshoppers.



ki:i"R'i OF mi-: c< >.MMI>>I< I.M-:K> 01



Tlio most marked changes in development are seen in butterflies, moths, flies,
beetles and bees. Comparatively few understand the relations existing between the
voracious caterpillar, the quiet brown pupa or brightly colored chrysalis, and the
beautiful moth or butterfly. The young caterpillar emerges from the egg and at once
begins feeding, casting its skin from time to time in order to allow of increase in size.
This, the larval stage, is the period of assimilation and growth, and it is while in this form
that most insects are destructive. When full grown, the caterpillar (Plate i, figure i)
sheds its skin and changes to a pupa, a form which is usually brownish and subconical
(Plate i, figures 7, 15). This transformation is frequently preceded by the spinning
of a cocoon (Plate I, figure 14) or by the formation of an earthen cell. During the
pupal stage no food is taken and only a very limited activity is possible. It is the
period of reorganization. From the comparatively simple caterpillar, there is de-
veloped the delicate moth or butterfly, which in due time emerges from the shroud-
like pupal case. After a time, pairing occurs, eggs are deposited and the life cycle
again commenced. On account of the great changes from the caterpillar through the
pupa to the adult, the identity of u species in the various forms can usually be
established only by rearing. All insects presenting such marked changes in their
development are said' to undergo a complete metamorphosis or transformation, a
change which will be found true, in endless variation, of all members of the bee,
beetle, fly, butterfly and moth families.

A study of the habits of injurious insects in their various stages is the foundation
of applied or economic entomology, for such investigations usually reveal one or more
weak points in the life history of each pest that render its control comparatively easy.



Wl)ite Aarl^cd Tussoc!<j

A'otnli>f/uis lencostigma Abb. and Sm.

This insect appears to thrive best in cities and villages and some seasons proves
a veritable scourge in certain localities. In Albany and Troy, the horsechestnuts are
usually partly defoliated each spring and occasionally stripped of all their leaves by
the voracious caterpillars of this moth. The lindens frequently suffer nearly as much,
and the maples and elms come in for a goodly share of attention from year to year.
The above is probably true to a great extent of most of the cities and larger villages
in the state. The summer of 1898 was marked by the abundant presence of this
insect, and the extensive defoliations which occurred at the time aroused the people
to the necessity of fighting the pest. This was done so effectively that very little



trouble with this caterpillar was reported in 1899.



FISHERIES, GAME AND FORESTS. 5

Description, The full grown caterpillar has a coral red head, a pair of long black
plumes just over it, a single one at the opposite extremity of the body, four delicate
yellowish or white brush-like tufts on its back and just behind them, separated only
by a segment, two small, retractile, red elevations. Along the back, except for the
tubercles and tufts, there is a broad black band bordered by yellowish subdorsal
stripes. Each side is dark gray, except the yellowish tubercles A black line indi-
cates the position of the spiracles or breathing pores, and below this latter line it is
yellow, the legs usually being paler (Plate i, figure i). This gives the general
appearance of the caterpillar after it has become half or two-thirds grown, and at a
time when its depredations begin to be apparent. The recently hatched larva is a
pale yellowish or whitish creature with long, irregular hairs. As it feeds, increases in
size, and casts its skin (Plate i, figure 5) from time to time, one after another of the
characteristics of the full grown larva are assumed.

When maturity is reached, the larva; spin their thin cocoons in the crevices of the
bark (Plate i, figure 4), interweaving their long hairs, and within this shelter transform
to yellowish white pupas more or less shaded with dark brown or black (Plate I,
figure 7).

The difference between the sexes in the adult stage is strikingly shown by com-
paring in plate i, figure 2, an illustration of the male, with figure 3, a representation
of the female. The former is a beautiful moth with large, feathery antennas, tufted
legs, and the wings and body delicately marked with several 'shades of gray and
grayish white. On the other hand, the female is a 'nearly uniform gray, with si-mple
antennae, and but rudimentary wings.

The eggs are deposited on the empty cocoon under a conspicuous white mass of
frothy matter (Plate i, figure 3), which soon hardens and forms a very effective pro-
tection. The individual egg is nearly spherical, about j*j inch in diameter, white
or yellowish white, and with a light brown spot surrounded by a ring of the
same color.

Life History and Habits. The winter is passed hi the conspicuous, white, easily
removed egg masses, the young emerging about the latter part of May in this latitude.
They begin to feed on the more tender lower epidermis ot the leaf and soon devour
all but the principal veins. While young, the caterpillars frequently hang by a silken
thread and with continued jarring many may drop to the ground. The growth of the
caterpillars occupies a month or a little more, pupation occurring the latter part of
June and early in July. In Albany most of the larvae had pupated by July 7 in 1898,
and some recently deposited egg masses were to be seen at that time. A few
individuals spin up earlier than the mass and some do not till numerous egg clusters
indicate that most of the insects have already completed the round of life.



8



K! I'' 'U I i i| ! Ill ( . >MMII< >\! K- i 'I



form of a scraper, tin- task is easily ami quickly performed. Dr. Howard has recom-
mended the use i >f creosote oil for the destruction of the eggs, since each mass has
only to be moistened with the substance In winter it is necessary to add some
turpentine in order to keep the creosote- liquid. On account of the female being
windless, a tree once thoroughly cleaned will not become reinfested very soon it' larv;L-
are not abundant near by, and even then a band of 1. >,-.,- cotton bound tightly near its
middle around the trunk and the portion above the string turned down, will prevent
their ascending and a consequent re-infestation. It should be kept in mind that only
the eggs must be collected or destroyed, on account of the beneficial parasites which
may occur in cocoons not bearing egg masses. This is specially true in the autumn
and applies to a certain extent in the spring, since it has been shown that some-
parasites hibernate as larvie within the cocoons of the host, and if these are collected
anil destroyed, it means the death of many beneficial forms. The egg masses are




Figure . DIBRACHVS BOUCIIK \xt -, : a, larva ; A, pupa; c, nilult fem;ile greatly enlarged; J, head larva;
e, antenna of adult still more enlarged. Lines beside figures represent natural size. (After Howard: I'. S.
Department Agriculture, Division Entomology. Tech. ser. No. 5, 1897).

more readily seen after the leaves have fallen and in localities like Albany, where one
annual generation is the rule, the gathering of the eggs may well be deferred until
autumn, or, better still, until early spring, since there will then be less chance of
destroying valuable parasites. As the young caterpillars begin to hatch the latter
part of May, collection of the egg ma-ses can not be delayed with safety after the
middle of that month. In Boston, New York city and more southern localrties, it
may be necessary to collect in midsummer the eggs laid by the first brood of moths.
In case it is impracticable to collect the eggs, dependence must be placed upon
spraying with some arsenical poison. This is satisfactory if properly done early in
the season under favorable conditions. In many instances there will be more or less







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FISHERIES, CAME AND FORESTS. 9

delay and in practice it is very difficult to have the spraying properly done, and then
there may be hindrances incident to several days or a week of rain at the time the
poison should be applied.

Not a few wait till the trees show signs of serious injury and then ask for some
means of stopping the ravages. Under such conditions, resort may be had to spraying
with a larger proportion of poison in order to kill the caterpillars quickly or they may
be shaken from the limbs, provided the tree is not too large. The latter means will
give a certain amount of relief where practicable and should be supplemented by the
use of cotton bands or other means of preventing the ascent of those shaken from
the tree.

In order to spray trees successfully, certain rules must be observed. Apply the
poison at the time the insects begin to feed and where they must eat it if the tree is
attacked. In the case of this insect and the following, it is best to throw the spray on
the under surface of the leaves so far as possible, as the young caterpillars prefer the
tender lower epidermis. Do thorough work, that is, try to cover every leaf with the
mixture and spray till the tree begins to drip, but no more. The finer the spray, the
better, as a more even distribution is ensured. The poisonous mixture must be kept
agitated while spraying is in progress. While a power spraying apparatus is the best,
good work can be accomplished with hand pumps, but plenty of hose must be supplied
as a fine spray can not be thrown far and it is, therefore, usually necessary to do more
or less climbing. One pound of Paris green, one pound of quicklime, to 150 gallons
of water is a very good spraying mixture for this insect. London purple may be used
in place of Paris green, if desired. Though costing a little more, arsenate of lead is
probably the best poison for most to use, since it adheres an indefinite time to the
foliage, its whiteness renders it easily detected, and it can be applied in large
quantities without danger of burning the foliage. It is prepared as follows: Dissolve
eleven ounces of acetate of lead (sugar of lead) in four quarts of water in a wooden
pail and four ounces of arsenate of soda ($0% purity) in two quarts of water in another
wooden pail. As the acetate of lead dissolves rather slowly in cold water, the process
can be hastened by using warm water. Pour the resulting solutions into the spraying
tank which should contain about eighty gallons of water. This poison may be used in
much larger proportions without the slightest danger of burning the foliage.

Polder Spraying Out/it. In the extended work against insects conducted by
certain cities and villages, it has been found necessary to have apparatus that will
admit of more rapid work than is possible by hand. This has led to the refitting of
retired fire engines and the designing of more or less cumbersome outfits for this
purpose. In all cases these makeshifts have been successful, though they are not
usually so satisfactory in operation as those specially fitted for the purpose. Probably



1O REPORT OF THE COMMISSIONERS OF

the best apparatus yet designed for spraying trees is that constructed under the
direction of Dr. E. B. Southwick, Entomologist of the Department of Public Parks of
the city of New York, which is the form used in Albany. The whole outfit is represented
in the accompanying figure (3). It consists of a "Daimler" gasoline motor operating a
Gould force pump the motor and pump, weighing but 300 pounds, can be placed in
the bottom of a spring wagon along with the one hundred gallon tank containing the
poisonous mixture. This motor has the advantage of being almost noiseless in
operation and is scarcely noticed by passing horses. It is very inexpensive to operate
as a gallon of gasoline is sufficient for a day and it requires little attention. The
smallest size Gould three-piston pump is the one used with the motor, though Dr.
Southwick now recommends a larger one in order to utilize the power more fully. This
apparatus, with the tank, 400 feet of ->^ inch rubber hose and other necessary fittings,
can be bought for about $500. Other engines and pumps could undoubtedly be used
and would give excellent results. This power can easily supply four lines of hose,
though in Albany it was found that not more than two could be used to advantage
in most places.



Forest Tent Caterpillar: Aaple Worm.

Clisiocampa disstria Hiibn.

Stripping a large proportion of the foliage from maples has been a marked
characteristic of this species for the last three years in many sections of New York.
In 1897 and 1898, the sugar maples of Delaware, Greene and Otsego counties suffered
most severely from the attacks of this pest, large areas being left with hardly a green
leaf. The destructive work of this caterpillar in 1899 was more general than in the
preceding two years, there having been complaints received from about half the
counties in the state, and in some sections the depredations were worse than ever.
This species appeared in force in many cities and villages, threatening thousands of
handsome shade trees with defoliation, and had it not been for most energetic efforts
on the part of local authorities and private individuals, many maples along streets and
in parks would have been stripped of leaves. As this native species is generally
distributed, its comparative abundance in a locality is due to natural causes, favorable
or otherwise, and very rarely can it be said that the insect has migrated to any extent,
except in a very local and restricted sense.

Description. This insect can be distinguished at once from the common apple
tree tent caterpillar, Clisiocawpa amcncana Fabr., by the fact that no conspicuous web
tent is spun. This caterpillar (Plate i, figure 13) has a row of somewhat diamond



FISHERIES, GAME AND FORESTS. . I I

shaped, whitish spots down the middle of the back, while its close relative possesses
a narrow whitish stripe in place of the dots. The egg belts (Plate I, figure 12)
encircling the more slender twigs, are smaller, usually with one or two wrinkles or
depressions in the brownish, protective covering, and the ends of the belts are more
abrupt than are those of the species usually found on apple trees. An average sized
egg belt, collected in Albany, of the forest tent caterpillar contains about 150 eggs.
If an egg is opened in September or later, a well developed, nearly black caterpillar
with a few whitish hairs may be seen. The recently hatched caterpillars are nearly
black with whitish hairs and are found clustered together or traveling along certain
silk lined paths. After the second molt, the characteristic row of whitish spots along
the back appears and as the caterpillars increase in size, the colors become brighter
and more distinct. The white or yellowish white cocoons (Plate 1, figure 14) are
spun in leaves on the tree or lying on the ground, in crevices of the bark, under
stones, in fence corners and under almost any convenient shelter. Within the cocoon
is found the dark brown pupa (Plate i, figure 15). The moth is a light, buff colored,
active creature (Plate i, figures 10, 11). The male may be recognized by his richer
coloring, smaller size and feathery antennae (Plate i, figure 11).

Life History and Habits. The winter is passed by the well developed larva
within the egg shell. On the appearance of warm weather, the young caterpillars
begin to emerge and if no food is at hand, await the unfolding of the leaves. From
eggs received in early spring, young caterpillars emerged April i 7. There is consider-
able latitude in the time of hatching, even in one locality, about a month as reported
by V. H. Lowe, and there is a corresponding variation in the time the caterpillars attain
maturity. As the young increase in size, they molt from time to time, leaving their
cast skins in small clusters on the bark (Plate i, figure 16). When not feeding, the
larvae may be found in clusters on the limbs. They also resort to such places when
about to molt, an operation requiring at least a day or two. A wind or jarring causes
these creatures when small to drop and suspend themselves with a silken thread, a
position very annoying to persons obliged to pass under an infested tree, and as many
shade trees were attacked last summer, this feature was painfully apparent. If the
shock is sudden the caterpillars drop without spinning a web. As they become
about half grown, they frequently form good sized clusters on the larger limbs and
trunk of an infested tree. If the creatures are very abundant, they may strip the tree
before full growth is attained and then be forced by hunger to invade neighboring
orchards. The maple leaves represented on plate I show well the work of this insect.
Ordinarily, as the caterpillars approach maturity, many of them forsake the tree and
crawl in all directions. Thus in obedience to a natural impulse, they may crawl in
numbers over walks, piazzas and swarm on sides of houses. This wandering, prior to



Explanation of Plate 1.



White Aarlsed Tus.socK noth {Notolophns ltuc$tis>na Abb. and Sm.).

1. Full grown caterpillar.

2. Male moth at rest.

3. Female moth laying eggs on her recently vacated cocoon.

4. Several cocoons.

5. Cast skins of caterpillar.-*.

6. Work of y<>img caterpillars on under surface of leaf.

7. Male pupa.

<X. Branch girdled by caterpillar.

9. End of branch broken off at the point where it was girdled.

Fore.st Tent Caterpillar: Aapte Worm (Clisiocainf>a Jhstria Hiibn.).

10. Female moth.

I I. Male moth.

12. Egg belt encircling twig.

13. Full grown caterpillar.

14. Cocoon in a leaf.

15. Pupa.

1 6. Cast skins of caterpillars.



* Plates 1-3 were executed from nature, under the author's direction, by Mr. 1,. H. Joutol of
New York city.



RETORT OF TI1K COM MISSioXKKS D| 1 ISHKKIK.S, CAMK AND KoKKSTS. 13



pupation, occurs about June i, the transformation to the pupa taking place from
about the middle to the last of June. The insect remains in the pupa state about two
weeks, the moths appearing the latter part of June and during July, mostly in
the latter month. The eggs are deposited during July, a large proportion of them
being laid on the lower twigs, but many are found over twenty feet from the ground
and numbers even in the tops of tall trees.

Food Plants. Like the apple tree tent caterpillar, this insect can subsist on a large
variety of plants. Its favorite species of oak in the southern states, as given by the
late Dr. Riley, are those belonging to the same group as the black oak. In New York
and adjoining states this insect is reported more frequently as defoliating the sugar
maple than any other tree. This may be owing to the fact that large sugar orchards
afford the most favorable conditions for the caterpillars in the north, and as the maples
are of greater value than forest trees, complaints of attack are more frequent. The
caterpillars have been reported by various writers as feeding upon the following trees
and shrubs : Linden, maples, locust, peach, plum, cherry, rose, strawberry, apple,
sweet gum (Liquidambar styracijiua), dog wood, "black gum," sour gum (Nyssa
sylvatica), ash, elm, black walnut, hickory, walnut, oak, black oak, post oak, white
birch, gray birch, willow and poplar.

Natural Enemies. Like the preceding, this species has a number of important
natural enemies. A fungous disease is known to attack this caterpillar, but at present
little has been done in attempting to disseminate it. One
of the most fruitful methods of keeping the pest in check
through the aid of its natural enemies, will probably be
found in encouraging and protecting the native birds known
to feed on it. Robins, orioles, chipping sparrows, cat
birds, cuckoos, the red eyed, white eyed and warbling
vireos, cedar birds and nuthatches have been observed
feeding on forest tent caterpillars by Miss Caroline G.
Soule. "The nuthatches would stand by a patch of larvae Fig ' 5 ( ^ e I ^ le GROUND BEETLE>
lying close together below a tar band on a tree and eat so

voraciously and with such an entire abandonment of self-consciousness that I could
go close and put my hand on them before they would fly. This experience was
repeated several times." Mr. E. H. Forbush, Ornithologist to the Massachusetts
State Board of Agriculture, has kindly supplied rne with the following list of native
birds observed by him feeding on forest tent caterpillars : Oriole, black billed
cuckoo, yellow billed ^cuckoo, crow, blue jay, redstart, nuthatch, wood thrush,
chewink, black and white creeper, red eyed vireo, flicker and scarlet tanager. Mr.
V. H. Lowe has observed the black capped chickadee feeding on the eggs and the




REPORT OK THE COMMISSIONERS OF



robin on the caterpillars, beside others mentioned above. Professor C. M. Weed
states that the robin, chipping sparrow, yellow bird and English sparrow feed


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