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THE SATIN MOTH 
 
 AN INTRODUCED ENEMY OF 
 POPLARS AND WILLOWS 
 
 A. F. BURGESS 
 
 Entomologist in Charge of Gipsy Motli and 
 Brown-tail Moth Investigations 
 
 Rows of 25-Year-Old Carolina Poplars. A favorite food of the Satin Moth 
 
 UNITED STATES DEPARTMENT OF AGRICULTURE 
 DEPARTMENT CIRCULAR 167 
 
 Contribution from the Bureau of Entomology 
 L. O. HOWARD, Chief 
 
 Washington, D. C. 
 
 Issued May, 1921 
 
 WASHINGTON : COVERNMENT PRINTINQ OFFICE : 1921 
 
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 OfiTajpijj 
 
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 ( P.^'ARY OF CONGRfeSS • 
 
 OCT 3 1933 
 
 •\«irisn»r« <U i>'.t(;i)«*t-"r<TV 
 
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U THE SATIN MOTH: AN INTRODUCED 
 ^ ENEMY OF POPLARS AND WILLOWS. 
 
 DISCOVERY OF AN UNWELCOME IMPORTATION. 
 
 The satin moth {Stilpnotia salicis L.), a well-known insect in 
 Europe, was first reported in the United States about July 1, 1920. A 
 crew of men employed by the Metropolitan Park Department found 
 a number of Carolina poplar trees located on the Fellsway at the 
 Maiden and Medford city line just north of Boston that w^ere being- 
 defoliated. The gipsy moth was first suspected as the probable cause 
 of the trouble, but specimens were later collected by the foreman and 
 turned over to Mr. X. N, Habberley, the parTj superintendent. As he 
 did not recognize the caterpillars, he brought them to the Gipsy 
 Moth Laboratory at Melrose Highlands. They did not seem to be a 
 natiA'e species, and accordingly Mr. S. S. Grossman, one of the assist- 
 ants at the laboratory, visited the insect collections in Boston and 
 Cambridge and was able to identify the insect as the satin moth by 
 comparison with larvae in the collection of the Museum of Compara- 
 tive Zoology at Cambridge, Mass. Confirmation of the determination 
 was later secured from specialists at the United States National 
 Museum. As this insect is closely related to the gips}^ moth and the 
 brown-tail moth, having habits which are similar in some respects to 
 those of each of these species, considerable anxiety was felt as to the 
 amount of damage it might cause. 
 
 The caterpillars were nearly full-grown at the time they were 
 found and some of the trees were badly defoliated. A hasty examina- 
 tion showed that the most severe defoliation was in the region where 
 the caterpillars were first reported, and several trees in a small group 
 of Lombardy poplars were completely stripped. (Fig. 1.) A row of 
 large California poplars directly in the rear of a number of houses 
 were being heavily eaten and the owners complained bitterly about 
 the superabundance qf caterpillars which invaded the houses and 
 made life extremeh' disagreeable, as they frequently crawled upon 
 the tables and even on the beds, and in spite of all the care that 
 could be taken it seemed impossible to keep them out. The sides of 
 these houses nearest these trees were heavily stocked with larvae, par- 
 ticularly under the eaves and clapboards, and in a few days many of 
 them began to pupate. 
 
 CONTROL WORK UNDERTAKEN. 
 
 As soon as the identity of the species was determined, arrange- 
 ments were made with the superintendent of parks and with the 
 State forester's office, which in Massachusetts has charge of the gipsy- 
 moth control work, to cooperate with the Bureau of Entomology. 
 No special funds were available for the purpose, but work was under- 
 taken to reduce the damage and danger of spread as much as possible 
 
 3 
 
4 Department Circular 167, I . S. Dept. of Agriculture. 
 
 until more complete information as to the nature and possibilities 
 for destructiveness of the insect could be determined. 
 
 Arrangements were made that the Park Department should de- 
 stroy as many of the caterpillars and pupae as possible on the trees 
 alonff the Parkway which were under its control ; that the State 
 
 
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 in.. 1. Kow ol' Luuibard.v poplar trees, the three ou the left completely defoliated 
 by the satin moth (Stilpnotia ftalicis) ; the others partially defoliated. July, 1920. 
 
 forester's office should examine the residential, property in and 
 around the center of infestation and destroy the insects thereon, and 
 that the Bureau of Entomologj^ of the United States Department of 
 Agriculture should scout as much as possible of the outlying terri- 
 tory^ to determine the extent to which the insect had spread, secure 
 
The Satin Moth. 5 
 
 field and laboratory data on the habits and life history of the insect, 
 and obtain all possible information on the best methods of control. 
 
 Accordingly, the Park Department immediately sprayed the trees 
 along the Parkway in and about the worst infested part of the terri- 
 tory ; but, owing to the fact that most of the larvae were nearly full- 
 grown, the treatment was not very effective. It also employed a crew 
 of trained gipsy-moth men to patrol the trees and crush all the 
 larvae within reach. Later these men were kept busy crushing pupa3 
 and treating the egg masses with creosote. 
 
 At the same time assistants from the State forester's moth force 
 carried on similar work on the privately-owned grounds adjoining 
 the Parkway and large numbers of the insects were destroyed. 
 
 The scouts supplied by the Bureau of Entomology commenced an 
 examination of the surrounding territory, particularly where poplar 
 or willow trees were present ; but as scattered, though small, infesta- 
 tions were found each day, they began working in towns more remote 
 from the center. 
 
 Investigations were also begun by experts from the Gipsy Moth 
 Laboratory, and such time as could be spared during the busiest sea- 
 son of the year was devoted to a study of the behavior of the insect 
 in the field, its food plants and enemies. 
 
 As soon as the moths began to emerge as many as possible were 
 crushed, but as quantities of the caterpillars pupated within curled- 
 up leaves on the trees, the method was only partially effective. Both 
 sexes of the moth fly readily and are attracted to brilliant lights. 
 Observations at night materially assisted in securing records of the 
 spread of the insect. 
 
 THE INSECT, ITS DEVELOPMENT AND HABITS. 
 
 Daring the summer of 1920 the following facts were learned con- 
 cerning the insect : 
 
 THE MOTHS. 
 
 The insect derives its name from the white, satinlike appearance 
 of the moths (fig. 2), which are larger than most of the white moths 
 native to New England and have no colored markings on the wings. 
 
 The males are 15 to 20 mm. in length and the females 20 to 25. 
 The head, thorax, and abdomen are black but densely covered with 
 long white hairs, so that they resemble the color of the wings, which, 
 as stated, have a satiny luster. The eyes are black. The legs are 
 black and the femora are densely covered with long white hairs. The 
 tibiae and tarsi are sparsely covered with white hairs and ringed with 
 white overlapping scales which give the appearance of alternate 
 bands of black and white. The dorsal side of the antennal shaft is 
 white, the pectinations brown to black. The expanse of the fore- 
 wings is from 35 to 55 mm. The females usually are slightly larger 
 than the males. 
 
 THE EGGS. 
 
 The eggs are laid in somewhat elongated patches 13 to 22 mm. in 
 length and coyered with a white secretion which holds them together 
 
6 Department Circular 167, V. S. Depi. of Agriculture. 
 
 in the cluster. (Fig. 3, i>, C.) The}^ are very conspicuous and are 
 easily distinguished from the egg masses of other moths. Dissections 
 .shoM- that a female usually produces about 550 eggs, although some 
 
 Fig. 2. — The satin moth ; Male above, female below. Enlarged. 
 
 individuals la}^ a larger number. If the female is disturbed she fre- 
 quently deposits more than one cluster. She may fly from the place 
 where egg laying was begun and continue the operation in another 
 locality. Although the eggs are usually laid on the underside of the 
 
The Satin Moth. 
 
 Fig. 3. — The satin luotli : o, Toplar leaf partially skeletonized by small lai-vae (small 
 larva shown below leaf) ; h, ejrg cluster on leaf ; c, egg cluster on bark. 
 
8 Dcparlmciit Circular 167, F. S. Dept. of Agriculture. 
 
 leaves and on the branches and trunks of the trees, they are sometime^ 
 deposited on grass, Aveeds, or stones, and even on the ground if no. 
 more convenient j^lace is available. 
 
 In 1920 the first eggs were observed in the field July 6, and an 
 unhatched cluster was found as late as August 10. This indicate- 
 that egcr laying sometimes continues for about a month. Most of 
 the eggs were deposited about the middle of Jul3\ 
 
 Hatching takes place in about 15 days after the eggs are laid, but 
 this period is frequently shorter if the weather is hot. 
 
 THE LARV^. 
 
 First-stage larvcv. — Newly hatched larvse are 2 mm. long. The 
 head is brownish black, provided on front with a few short spines, 
 the mouthparts lighter in color. The body is brownish yellow, with 
 rows of slightly darker tubercles, which are thickly studded with 
 short brown spines and with a small number of long hairs. Molting 
 takes place in five or six days. 
 
 Second-stage larva" (fig. 3, A). — Larvse of the second stage are 
 4 mm. in length. The body is brownish black, except the dorsum 
 of the second and third thoracic and the third, fourth, fifth, eighth, 
 and ninth abdominal segments, which are yellowish white. The 
 dorsum of the sixth and seventh abdominal segments are each pro- 
 vided with a retractile tubercle. All tubercles except the latter are 
 thickly studded with short brown spines and a few long hairs. After 
 feeding five or six days the larva molts again. 
 
 Third-stage larva> and their Jiihernating pockets. — In the third 
 stage the larvse are 6 mm. in length. The body is slightly darker 
 in color than in the preceding stage and the tubercles are similarly 
 arranged. This makes the light colors on the dorsum more con- 
 spicuous. The larvse immediately seek shelter and begin the con- 
 struction of a small web, in which they hibernate. As a rule these 
 are made individually, but occasionally two or sometimes three 
 larvae Avill be found in one of tliese hibernating pockets. Crevices 
 or uneven places in the bark are sought by the larvse, and if the 
 cavity is not sufficiently deep a small amount of bark is excavated. 
 The cavity is then lined with silk and the larva spins a cover over 
 the entrance. After this is accomplished the larva contracts some- 
 what in size and is usually about 4 mm. long during the winter and 
 somewhat thicker than when it is active. The exposed surfaces of 
 these pockets are usually flat and are made so nicely and so closely 
 resemble the bark that they are difficult to see. They are circular to 
 oval in form, the shape depending on the contour of the crevice in 
 which they are made. The length is about 4 mm. 
 
 Many of these pockets have been found on the trunks of large 
 Carolina poplar trees (fig. 4), and it was at first thought that the 
 bulk of the larvse hibernate near the ground. Examinations have 
 shown that the pockets are present high in the trees and on the 
 
The Satin Moth. 
 
 9 
 
 branches Avherever small inequalities in the bark are present. Some 
 webs liave been taken on branches 60 feet from tiie "-round and others 
 
 Fig. 4. — Hibernating wi'bs or pockets of small larvae in tree trunk. Several webs arc 
 encircled with a white lino to show their location. There are other webs on this 
 bark. 
 
 on small twi<>s and attached to the scars where leaves have fallen. 
 While it is probable that most of the larvse remain in the pockets 
 
10 Departmeni (Arcnlar 167, T. S. Dept. of Agriculture. 
 
 tluring the winter, a feAV cases have been noted where they have 
 deserted them temporarily during the falL On December 15, 1920, 
 Mr. F. H. Mosher reported that a small number of the larvae were 
 crawling on the tree trunks at the Medford colony. The weather 
 was warm and had been preceded by several warm days. 
 
 The hibernation pockets are verj' inconspicuous and it is difficult 
 to find them even on a tree that is rather heavily infested. This 
 lieing the case the insect could have been brought to this country very 
 easil}' on poplar or willow trees or possibly on other species or on 
 bits of infested bark that was mixed in packing material. The color 
 of the webs resembles the bark so closely that they can be overlooked 
 very easily by the most careful inspector. 
 
 Feeding of the small caterpillars is confined to the epidermis of 
 both sides of the leaves, but if the infestation is severe most of the 
 foliage on the trees may be denuded so that onl}^ the ribs and frame- 
 work remain (fig. 3, JL). As most of this feeding occurs during the 
 first half of August, many of the leaves that are only partially eaten 
 turn brown and drop earlier than normal. While feeding at this 
 time of the year does not injure the trees as severely as the defoliation 
 by the larger larvae of the previous brood earlier in the season, it 
 renders them unsightly and is objectionable, particularly if they are 
 planted for ornamental purposes. 
 
 Observations in the field during 1920 indicated that feeding by 
 the small larvie was confined principally to different species of pop- 
 lar, the Carolina, Lombardy, Balm of Gilead, and silver leaf show- 
 ing the most defoliation. In the laboratory experiments wnllow was 
 equally favored, but the small larvae starved rather than feed on' 
 alder, apple, gray birch, elm, red oak, and white oak. 
 
 A few small larvae in the laboratory survived on black-oak foliage 
 and went into hibernation in a normal manner. This food plant 
 may therefore be important, as it is rather common in some sections 
 of New England. 
 
 Emergence in the spring has not been observed in this country, 
 but the larvae probably come out of the webs and begin feeding as soon 
 as sufficient foliage is available. After passing through several 
 molts they become full grown about July 1. 
 
 Full-grown larvit (fig. 5, T, D). — Larvae when full grown are 45 
 to 50 mm. long. The head is bluish black and covered with short 
 hairs. The bodj' is black, mottled with white markings of irregulai* 
 shape. These form distinct subdorsal lines on each segment of the 
 body and are enlarged into an additional row of somewhat square 
 white blotches on the dorsum of each segment. The latter are char- 
 acteristic of this species, make it conspicuous, and enable it to be 
 readily recognizable. The rows of tubercles are brown, and pro- 
 vided with many spines and hairs that are slightly lighter in color. 
 
 After feeding is completed the larvae seek shelter and spin loose 
 cocoons. Manv of these are made bv drawiner together the edges of 
 
The Satin Moth. 11 
 
 leaves on the trees. Cocoons are sometimes made in crevices in the 
 bark, in rubbish near the base of trees, or on the sides of buildings. 
 
 THE PUP^. 
 
 The pupa (fig. 5, A, Bj E). — The pupa is 20 to 25 mm. in length 
 and 5 to 7 mm. wide at the base of the abdomen. It is shiny black, 
 densely covered Avith long white silky hairs, except on the venter, 
 where the hairs are scarce. The pupa can easily be seen within the 
 cocoon. Pupation was at the maximum by July 6. The time spent 
 in the pupal stage averages nine days. 
 
 The first moth was found July 2 and for the next two weeks the 
 number increased. 
 
 EUROPEAN RECORDS. 
 
 This species is common in Europe and is mentioned briefly in the 
 writings of many European entomologists. It is reported as com- 
 mon in England and Ireland and throughout Europe, its range ex- 
 tending from Spain to Eastern Asia and as far north as Norway, and 
 it is said to be present in the Orient. One authority states that it 
 occurs from Lapland to middle Italy and from England to Peking. 
 A number of different races have been noted b}^ collectors and are 
 distinguished by variations in the coloration of the wings. 
 
 When abundant the moths are said to ^j in swarms and to migrate 
 long distances. The larvae feed chiefly on poplar and willow, but 
 one report states that oak foliage is eaten in England. 
 
 Usually the insect is controlled by parasites and natural enemies 
 and is not considered as a pest of first rank. 
 
 Some authorities state that the eggs ordinarily do not hatch until 
 spring, but occasionally hatching takes place in July or August if the 
 weather is hot, and the small larvae hibernate during the winter. 
 
 DISTRIBUTION IN THE UNITED STATES.' 
 
 Scouting work to determine the extent to which the insect has 
 spread in the United States was begun about the middle of July. 
 As it was supposed that the infestation was local and extended for 
 only a short distance around the area that was known to be badly 
 infested, directions were given the men to examine poplars and 
 willows and cover the immediate surroundings of the colony and 
 gradually increase the circle if more infested trees were found. Spe- 
 cial instructions were given to make careful search for the large 
 larvae or pupae, as the finding of these would indicate that the insect 
 had been present in this locality during the summer of 1919. So 
 many infested trees were found that a new plan of scouting was 
 adopted after the first week, the men being instructed to work in the 
 cities or towns nearest the infested center and to move out to the 
 
 ^ In July, 1920, a small colony of this insect was discovered by Mr. J. D. Tothill, of 
 the Entomological Branch, Dominion of Canada, at New Westminster, a suburb of Van- 
 couver, British Columbia. 
 
12 Department Circular 167, V. S. Dept. of Agriculture. 
 
 Fig. 5.— The satin moth: a, pupa, ventral view: b. pupa, lateral view; c, two full- 
 growii larva? on bark (a gipsy moth larva is shown on each side of photograph in 
 crevices of bark); d. full-grown larva; e, leaf cut away to show hairy pSm n 
 cocoon (larval molt skin shown above pupa). «, i. a. e, enlargedrc rSeS 
 
The Satin Moth. 
 
 13 
 
 next town as soon as infestation Avas found. This plan was followed 
 until the scouting was completed. Most of the work north and west 
 of Boston, with the exception of some towns in the Cape Ann region, 
 was done b}^ scouts from the Bureau of Entomology, while the region 
 above mentioned and a number of towns south of Boston were scouted 
 by regular assistants of the Massachusetts State forester's office. A 
 number of town and city gipsy-moth superintendents found and re- 
 
 FiG. 6. — Map of territory infested with tlie satin motli. 
 
 ported the moth from their municipalities, and this helped materially 
 in securing prompt information on the spread of the insect. 
 
 As a result of this work the insect is now known to occur over an 
 area of G42 square miles, including 60 towns in Massachusetts and 
 4 in New Hampshire. Large larvse or pupse were found in man^^ 
 of the towns indicated on the map (fig. 6) as discovered infested in 
 1920, Avhich shows that they were infested the previous year; in fact, 
 51 of the G4 towns were so infested. 
 
14 Department Circular 167, V. S. Dept. of Agriculture. 
 
 Although no infestation was found in a few towns that are sur- 
 rounded by infested towns, this does not indicate that the insect is 
 not present there. Scouting was done in them rather late to secure 
 the best results, and in some of them poplar and willow trees are 
 A-ery scarce. 
 
 As is the case with most introduced insects in this region, the 
 trend of spread has been toward the north and northeast. This is 
 undoubtedly due to the direction of the prevailing wind at the time 
 the moths are flying. 
 
 AGE OF THE COLONY. 
 
 The remains of the egg clusters of the satin moth do not adhere to 
 the trees very long after hatcliing taJ^es place. For this reason it is 
 rery difficult to secure information of value relative to the age of the 
 infestations found. 
 
 The worst infestation was in the area along the parkway at the 
 Medford-Malden line, and there is no doubt that the insect has been in 
 this locality, probably in small numbers, for several yeai-s. Informa- 
 tion from persons residing in this section does not throw much light 
 on the subject, as few have been able to distinguish this insect from 
 the gipsy moth. The latter has occurred in sufficient numbers in this 
 locality during some years to cause much annoyance and complaint. 
 Several men who work on the parkway state that the insect was 
 present in considerable numbers in this particular locality in 1919, 
 and that it was probably there before that time. Mr. C. V. Black- 
 burn took a few moths at electric lights in Stoneham in the summer 
 of 1919, and he states that they were rather common at the same 
 lights in 1920. In Watertown a single Lombardy poplar was found 
 badly infested by the local moth superintendent, Mr. Van D. Horton, 
 in July, 1920, and Mr. Horton states that the same species was present 
 the previous year, but in less numbei-s. 
 
 v A rather bad infestation was found in Cambridge, and Mr. Dug- 
 gan, who had pruned and cared for the trees in 1918, states that the 
 satin moth was present at that time, although he supposed that it 
 was a native insect. It is probable that the insect has been in this 
 country for several years and has only become abundant enough to 
 spread very rapidly during the past two or three years. 
 
 While it is impossible to determine the original source of the in- 
 festation, it is quite probable that the insect was brought into this 
 country during the dormant season in crevices of bark on live or dead 
 trees, and bits of infested bark that might be mixed in packing ma- 
 terial could easily furnish a means of transporting the insect. As 
 previously stated, the hibernating webs of the small larvee concealed 
 in the crevices of bark are so inconspicuous as to pass by the most 
 careful inspection unnoticed. 
 
The Satin Moth. 15 
 
 NATURAL ENEMIES. 
 
 The European publications indicate that the satin moth is ex- 
 tensively attacked by parasites. It is fortunate, therefore, that some 
 of the foreign parasites of the gipsy moth are already well established 
 in the infested area in New England. 
 
 Some of the first field observations showed that the imported 
 Calosoma beetle {CaZosoma sycophmita L.), which is one of the 
 valuable insect enemies of the gipsy moth, was attacking the larvae 
 and pupae of the satin moth. Both the adults and larvae of the beetles 
 were doing valiant service- 
 
 A few days later heavy parasitism of the large larvae of the satin 
 moth by Compsilura concinnata Meigen, another imported gipsy moth 
 enemy, was noted. A number of the records secured indicated that 
 it was causing higher mortality than Calosoma. Both of these bene- 
 ficial insects are abundant in the central area infested by the gipsy 
 moth, and Calosoma was found actively at work in some of the small 
 infestations in other towns. 
 
 A small hymenopterous parasite has been reared from the eggs of 
 Stil'pnotia sallcis. It has been determined as Telenomus calif omicus 
 Ashm. by Mr. R. M. Fonts, of the Bureau of Entomology. 
 
 The prospect of control of this insect by parasites is encouraging, 
 but it may be necessary to bring in from Europe some of its enemies 
 that do not exist here at present. 
 
 REMEDIES. 
 
 Time has not permitted experiments to be conducted to determine 
 the most eifective remedies. The larvae were so nearly full-grown 
 at the time they were first found that spraying did not prove effectual. 
 Later, after tlie eggs began to hatch, the trees on the Parkway were 
 sprayed with arsenate of lead and a number of trees on private 
 grounds were similarly treated. This spraying was partially effec- 
 tive, and on some of the trees feeding by the small larvae was greatly 
 reduced. The leaves of poplar trees do not hold spray material as 
 well as most foliage, hence special care in treatment and the addi- 
 tion of a " sticker," such as soft soap, is advisable. 
 
 Application of creosote to the egg clusters will destroy the eggs, 
 but it is an expensive method on account of the labor involved and 
 is only partially effective, because many egg clustei-s are deposited on 
 small branches and on the leaves and these can not be satisfactorily 
 treated. 
 
 It is impractical to require workmen to do extensive climbing in 
 poplar trees, as the brittle nature of the wood, and in this region the 
 results of the work of borers, particularly the leopard moth {Zeuzera 
 'pyrina Fab.), render such work hazardous. 
 
 It was hoped that spraying with a contact insecticide while the 
 tre.es were dormant would destroy the hibernating larvae, but as they 
 
16 Department Circular 167, U. S. Dept. of Agriculture. 
 
 make many of their webs on the twigs and in the tops of the trees, 
 this method appears to be impracticable. 
 
 In all probability spring spraying will prove satisfactory, al- 
 though no opportunity has been presented to test this method. 
 
 With our present knowledge of the insect, the following treatment 
 seems advisable for the season of 1921 : 
 
 Spray poplars and willows as soon as they are in full leaf with 
 arsenate of lead at the rate of 10 pounds to 100 gallons of water, 
 using soft soap for a " sticker." 
 
 If the infestation is severe, it may be necessary to repeat the opera- 
 tion by the middle of June. 
 
 If Qgg clusters are abundant on the trees in July, spray again Avith 
 the same material about August 1. 
 
 If these suggestions are followed and the amount of spraying is 
 governed by the density of infestation, satisfactory results should be 
 secured. 
 
 The experience of a full year's work on this insect will probably 
 result in a modification of these recommendations. 
 
 PROBABLE IMPORTANCE OF THE SPECIES. 
 
 To predict the ultimate importance of a newly introduced insect 
 is rather hazardous. If the feeding is confined to the poplars and 
 willows the damage Avill be greatly restricted. While these trees 
 are not considered of prime economic importance, there are certain 
 areas where they grow satisfactorily that Avill not support more use- 
 ful species. They are also effective for ornamental planting in cer- 
 tain situations and are valuable for this purpose. Should the species 
 change its menu to oak or other trees that are useful and common 
 in this country, the status of the problem will be greatly changed. 
 Another season will doubtless give the necessar}^ opportunity to de- 
 termine the destructive possibilities of this insect. 
 
 In the meantime, local moth superintendents, tree wardens, and 
 others who are engaged in the protection of trees from insect pests 
 should make sure whether or not the insect is present in the terri- 
 tory that comes mider their supervision and, if so, apply the spray- 
 ing program suggested. 
 
 The danger of the shipment of this insect to uninfested territory 
 is considerable. As it is practically impossible to guard against this 
 l)ossibility by inspecting trees during the dormant season, special 
 efforts should be made to examine the favored food plants of the 
 insect during July and August to determine whether the insect is 
 present. While this applies to the nurseries within the infested area, 
 it is necessary that the work be done in the areas surrounding them 
 if the danger of spread on shipments is to l)e eliminated. In cases 
 where infestation is found the treatment recommended should be 
 applied immediately. 
 
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