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on the same day. In 1916 hatching began on June 23 and ended August 20, the emerging larvæ being most numerous during the latter part of July.
Upon hatching, the larvæ climb trees and feed upon foliage. They are able to reach maturity only on the leaves of the bird cherry, and when compelled to subsist on the foliage of other species of cherry they invariably succumbed. The total feeding period of the larva varied from 8 to 24 days, with an average during 1916 of 12.3 days.
When the larvæ have reached full growth they burrow into the leaf mold or a short distance into the soil and form cells in which to pupate. The time spent in these cells was found to average 15 days, the shortest period being 12 days and the longest period 23 days. The total developmental period from hatching to emergence as adult averaged 27.2 days at Fredonia during 1916.
The chief factors in the natural control of the beetles are drowning of adults, reforestation which decreases the amount of the bird cherry, a carabid beetle (Lebia ornata Say) which attacks the beetles, and the cedar wax-wing (Bombycilla cedrorum Vieill) which was observed feeding on the adults. The cherry leaf-beetle is effectively controlled by arsenicals, preferably combined with bordeaux mixture, and nicotine sulphate; for the proper employment of which directions are given.
In view of the lack of detailed information on the bionomics of the insect, the occurrence of myriads of the cherry leaf-beetle (Galerucella cavicollis Le Conte) in fruit plantings thruout western New York in 1915 gave the initial impetus for a detailed study, which involved consideration of its origin, distribution, host plants, life history and susceptibility to control measures. This work has been conducted for three consecutive seasons, principally at Fredonia, which is located in the Lake Erie Valley with an altitude of five hundred to one thousand feet less than that of the Alleghany plateau where the species is normally of common occurrence. To insure accuracy the results of these studies were checked from time to time by observations of the beetle in its normal habitat. It should be stated that the extraordinary abundance of the insect led to simultaneous studies by other workers in this and several adjoining states, which will be duly noted elsewhere in this bulletin.
CLASSIFICATION AND SYNONYMY.
The cherry leaf-beetle belongs to an extensive family of beetles known as the Chrysomelidæ. It was described by LeConte who assigned it to the genus Galeruca. It was discussed in literature under the name Galeruca cavicollis until Horn, in 1893, made a critical study of the entire tribe and re-established the genus Galerucella which had been established by Crotch in 1873 to include species closely related to cavicollis but which coleopterists did not recognize. Many of the species at present listed in this genus were originally described as members of the genus Adimonia, and some writers have referred to the cherry leaf-beetle under the appellation Adimonia cavicollis. The statements of Packard relative to Galeruca sanguinea were shown by Schwarz to refer to cavicollis 2 and Lugger's account of a cherry leaf-beetle under the name Adimonia femoralis obviously refers to this same insect.
The present synonymy of the insect is as follows:
Galerucella cavicollis Le Conte
genera inhabiting North America (original description). Proc.
Acad. Nat. Sci. Phila., p. 216, 1865.
and Shade Trees, 5th Rept. U. S. Ent. Com., p. 529, 1890. Galerucella cavicollis. Horn, G. H. The Galerucini of Boreal
America. Trans. Amer. Ent. Soc., 20: 76-77, 1893.
mologist. Mich. Agr. Expt. Sta., 7th Ann. Rept., p. 93,
1894. Adimonia femoralis. Lugger, Otto. Minn. Agr. Expt. Station
Bull. 66, pp. 236-238; also Ann. Rept. of Minn. Expt. Sta., pp. 236-238,1900.
The cherry leaf-beetle was first described by Dr. LeConte 3 in 1865 from a single specimen collected in North Carolina. He named
1 Le Conte, J. L., and Horn, G. H. Classification of the Coleoptera of North America, pp. 348–349, 1883. 2 Schwarz, E. A. Insect Life, 4:94. 1891. a Proc. Acad. Nat. Sci. Phila., 1865, p. 216.
the insect Galeruca cavicollis, giving the description in Latin, but made no mention of its host plant. In 1893 Dr. Horn? redescribed cavicollis and placed it in the genus Galerucella where it has since remained. The known area of the distribution of the species is stated by Dr. Horn to be “from Canada to the New England and Middle States westward to Wisconsin; North Carolina (LeConte)." Zesch and Reinecke 2 in 1883 record the beetle under the caption Galeruca cavicollis as having been collected near Buffalo, N. Y.
The first mention of the habits of this insect is by Dr. Packard who in 1890 recorded the insect as occurring in abundance at Berlin Falls, N. H., eating holes in leaves of “wild cherry.” He also gave a brief description of the beetle, designating it Galeruca sanguinea, the name of a European species which it resembles. Schwarz 4 in 1891 called attention to the correct identity of the insect and said it is a common northern species.
The first recorded feeding of cavicollis on cultivated cherry is by Davis 5 in 1894 who observed the insect on this fruit at Bellaire, Mich. He designated the species Adimonia cavicollis, stating that a few beetles were observed feeding on wild cherry trees, and suggested the possibility of the species becoming a serious pest. He also described the larva for the first time. In 1896 Davis 6 again reported the appearance of the beetles in Michigan, which were in numbers sufficient to cause injury to cultivated trees. Mention is made of their feeding on the foliage of peach, cherry, apple and plum, and it is stated that arsenites were not satisfactory insecticides.
During the period of 1895 to 1899 inclusive the leaf-beetle seems to have been unusually abundant thruout the northern portion of its range and attracted the attention of a number of observers. However, Dr. John Hamilton' in 1895 reported the insect as rare in southwestern Pennsylvania but noted its occurrence on plants of the genus Prunus. In 1896 Dr. Lintner 8 reported having received specimens of this species from Ausable Forks, N. Y., on June 10,
1 Trans. Amer. Ent. Soc., 20:76–77. 1893. 2 Bul. Buffalo Soc. Nat. Sci., 4:12. 1883. 3 5th Rept. U. S. Ent. Com. p. 529. 1890. 4 Insect Life, 4:94. 1891. 5 Mich. Agr. Expt. Sta. 7th Ann. Rpt., p. 93; also Insect Life, 7:200. 1894. 6 Mich. Agr. Expt. Sta. 9th Ann. Rpt., p. 136. 1896. 7 Trans. Amer. Ent. Soc., 22: 371. 1895. 8 11th Rept. Ins. St. N. Y. pp. 197–198. 1896.
1895, from a correspondent who recorded the occurrence of “thousands" of the beetles on cultivated cherries and stated that beetles sent from cherry trees were also feeding on a young chestnut tree." The attacks of the insect on the latter host have never been verified. Lintner referred to the literature of the species and said, " the occurrence of this insect on the garden cherry while previously known only on the wild is another instance of the many similar changes known of our native insects from wild to cultivated food plants." Barrows and Pettit 1 in 1898 mentioned the insect as feeding on cultivated cherries in Michigan during 1897 and gave for the first time a general summary of its life cycle. For the prevention of injuries by the insect paris green, fish-oil soap and kerosene emulsion were advised.
In 1897 Johnson 2 stated that “myriads of the beetle and its larvæ were observed during the first week of September, devouring the leaves of the fire cherry (Prunus pennsylvanica) at Ricketts, Wyoming Co., Pa." Dr. Felt 3 in 1898 found the insect causing injury about Corning in Steuben County, N. Y. Dr. Smith 4 in 1898 observed the species feeding on peach in Pennsylvania and Chittenden 5 during the following year recorded injury to peaches at Lebanon and Spruce Creek in the same state. The account of the latter was the most comprehensive discussion of the species previous to 1915. In addition to the two localities just enumerated he recorded injury to cultivated cherry foliage at St. Ignace, Mich. He also gave a description of the egg and determined the incubation period for the latitude of Washington, D. C. Arsenicals were recommended for the protection of plantings. Dr Lugger 6 in 1899 reported the cherry leaf-beetle under the appellation Adimonia femoralis Melsh. as being numerous on the native plum” and P. pennsylvanica in Minnesota, and Harvey ? during 1900 recorded the insect by the name Adimonia cavicollis as being injurious to cherry in the vicinity of Orono, Maine, during 1899.
137th Ann. Rept. Mich. State Bd. Agr. 1897–8, pp. 93-4. 1898. 2 3rd Ann. Rpt. Penna. Agr. Dept., Pt. II, pp. 106-7. 1897.
3 Country Gentleman, 63:471; 14th Rpt. State Ent. N. Y. p. 235; U. S. Dept. Agr. Div. Ent. Bul. 17, n. s., p. 20. 1898.
4 U. S. Dept. Agr. Div. Ent. Bul. 17, n. s., p. 23. 1898.
6 Minn. Agr. Expt. Sta. Bul. 66, pp. 236-238. 1899. Minn. Agr. Expt. Sta. 5th Ann. Rept., pp. 152-154. 1899.
7 Maine Agr. Expt. Sta. Bul. 60, p. 35. 1900.
For an interval of fifteen years, from 1900–1915, there is apparently no mention of cavicollis causing injuries in fruit plantings. However, during this interval publications were issued which deal either with groups of insects that attack certain plants or certain lists of Coleoptera, in which there are references to cavicollis. In 19011 and again in 19062 Felt mentioned feeding by the beetle on P. pennsylvanica in the Adirondacks. Pettit in 1901 stated that the insect occurs thruout the upper peninsula of Michigan, and in 19054 he mentioned the species among insects injurious to the cherry. In 1902 MacGilliyray and Houghton reported cavicollis from Axton, N. Y., on the bird cherry. Washburn in 1903 briefly mentioned the insect in a list of cherry pests. In 1909 Smith' listed the beetle as a pest on peach, plum and cherry. Blatchley8 in 1910 gave tables for separating the several species of the genus Galerucella including cavicollis found in the state of Indiana. Mention was also made of its distribution, giving the range only east of the Mississippi River. In 1911 Gossard' gave remedies for the control of the pest, listing it with other cherry insects but made no mention of any outbreaks occurring in Ohio. In 1912 O'Kanclo referred to the beetle as a destructive insect of cherry and gave a partial life history and remedies.
The outbreak during 1915, from the standpoint of numbers of beetles and the extent of territory infested is the most extraordinary on record for the species. On account of the attention that was. directed to the insect by its superabundant numbers over a large area in several states, a number of contemporaneous and independent investigations were initiated.
Dr. Surface 11 recorded the insect as destructive to cherry, apple and other plants in Lycoming County, Pa., during 1915, and Parrott 12 gave an account of the species in New York, briefly summarizing its life history and experiments on control measures.
1 17th Rept. State Ent. N. Y., p. 861.
Rept. N. J. State Mus., p. 347. 1909.
12 N. Y, Dept. Agr. Cir. 130, pp. 174–176; Proc. 61st Ann. Meeting West. N. Y. Hort. Soc., pp. 115, 123.