ft ?[ / U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY— BULLETIN No. 93. L. O. HOWARD, Entomologist and Chief of Bureau. THE SUGAR-CANE INSECTS OF HAWAII. BY D. L. VAN DIXE, Special Field Agent. Issued June 15, [" , o& N »m T U.S. DEPOSITORY WASHINGTON: GOVERNMENT PRINTING OFFICE. 1911. Bui. 93, Bureau of Entomology, U. S. Dept. of Agriculture. Plate I. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY— BULLETIN No. 93. L. O. HOWARD, Entomologist and Chief of Bureau. THE SUGAR-CANE INSECTS OF HAWAII. BY D. L. VAX DIXE, Special Field Agent. I— fed June 15. 1911. WASHINGTON: GOVERNMENT PRINTING OFFICE; 1911. BUREAU OF ENTOMOLOGY. L. O. Howard, Entomologist and Chief of Bureau. C. L. Marlatt, Entomologist and Acting Chief in Absence of Chief. R. S. Clifton, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. Chittenden, in charge of truck crop and stored product insect, investigations. A. D. Hopkins, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. F. M. Webster, in charge of cereal and forage insect investigations. A. L. Quaintance, in charge of deciduous fruit insect investigations. E. F. Phillips, in charge of bee culture. D. M. Rogers, in charge of preventing spread of moths, field work. Rolla P. Currie, in charge of editorial work. Mabel Colcord, librarian. Southern Field Crop Insect Investigations. W. D. Hunter, in charge. W. D. Pierce, J. D. Mitchell, E. S. Tucker, T. E. Hollow ay, G. D. Smith, E. A. McGregor, Harry Pinkus, W. A. Thomas, Thomas Lucas, engaged in cotton-boll ueevil investigations. F. C. Blshopp, W. V. King, H. P. Wood, G. N. Walcott, engaged in tick investigations. A. C. Morgan, G. A. Runner, S. E. Crumb, engaged in tobacco insect investigations. T. C. Barber, C. E. Hood, engaged in sugar cane and rice insect investigations. F. C. Pratt, engaged in cactus insect investigations. D. L. Van Dine, Wilmon Newell, R. A. Cooley, A. F. Conradi, C. C. Kbumbhaar, collaborators. 2 LETTER OF TRANSMITTAL. U. S. Department of Agriculture, Bureau of Entomology, Washington, D. C, December 22, 1910. Sir: I have the honor to transmit herewith for publication a manu- script entitled "The Sugar-Cane Insects of Hawaii/' by Mr. D. L. Van Dine, recently a special agent of this Bureau, and for several years entomologist of the Hawaii Agricultural Experiment Station. The manuscript includes a discussion of the present status of the sugar industry of the Hawaiian Islands and treats of the principal insect enemies to this important industry, which is rapidly assuming large proportions in our Southern States owing to the increased acreage which is being planted to cane. I would recommend its publication as Bulletin No. 93 of the Bureau of Entomology. Respectfully, L. O. Howard, Chief of Bureau. Hon. James Wilson, Secretary of Agriculture. PREFACE. The acreage devoted to sugar-cane culture in the southern United States has increased rapidly in recent years. Some of the cotton lands, abandoned because of the depredations of the cotton boll weevil, are being planted to cane. % New lands are being planted to the crop in the Rio Grande valley and in the reclaimed areas in the lower Mississippi valley. It is stated that quite an area of land in process of reclamation in the State of Florida will be planted to sugar cane. It is desirable that the experience obtained through investigations of insects injurious to sugar cane in the Hawaiian Islands be placed at the disposal of the planters in our Southern States in order that the sugar industry in those States may receive practical benefit therefrom. The Hawaiian planters are well provided with expert advice and have at hand numerous reports dealing with the subject, which latter, unfortunately, are not available for general distribution. This report is written primarily, therefore, for the information of our mainland planters. Acknowledgment should be made of the courtesies extended to the writer by the members of the entomological staff of the Hawaiian Sugar Planters' Association Experiment Station during his return visit to the Hawaiian Islands in March and April, 1909. D. L. Van Dine. C N TEXTS. Page. Location and climate of the Hawaiian Islands 9 The sugar industry in Hawaii 9 Sugar-cane insects 11 The sugar-cane leafhopper (Perkinsiella saccharicida Kirk.). 12 Distribution 12 Appearance of the leafhopper in Hawaiian cane fields 12 Description of the leafhopper 13 Dispersion of the leafhopper 14 Life history and habits 15 Symptoms of leafhopper injury 17 Character of injury to the cane .18 Extent of injury 19 Factors responsible for the outbreak of 1903 20 The leafhopper and beekeeping 20 Control of the leafhopper 22 Direct measures 22 Insecticides 22 Collection by nets 22 Cutting and burning in the infested centers 22 Stripping the leaves 23 Burning of trash after harvesting 23 Indirect measures 23 Selection of varieties of cane for planting 23 Cultural methods on the plantation 25 Diversification of crops 26 Control of the rind disease of sugar cane 26 Natural enemies 28 Species already present in the Hawaiian Islands 28 Special introductions 29 Related species 34 The Hawaiian sugar-cane borer ([Sphenophorus] Rhabdocnemis obscurus Boisd . ) 35 General characteristics 35 Distribution 36 Occurrence in Hawaii 36 Life history and habits 37 Control measures 39 Selection of varieties for planting 39 Irrigation 39 Burning of trash 39 Selection of noninfested seed cane 39 Picking and baiting 39 Related species 40 The Hawaiian sugar-cane leaf-roller (Omiodes accepta Butl.) 41 Early history in the Hawaiian Islands 41 Control measures ' 41 Parasites 41 7 8 THE SXJGAR-CANE IXSKCTS OF HAWAII. Sugar-cane insects — Continued. rage. The sugar-cane mealy-bug (Pseudococcus calceolaria Mask.) 43 Identity 43 Related species 43 Food plants 43 Life history and habits 44 Control 44 Selection of seed cane 44 Burning of the trash 44 Natural enemies 45 Miscellaneous insects affecting sugar cane in Hawaii 45 Rats injuring growing sugar cane in Hawaii 47 Index 49 ILLUSTRATIONS. PLATES. Page. Plate I. Map of the Hawaiian Islands Frontispiece. II. The sugar-cane leafhopper (PerKnsiella saccharicida) . Fig. 1. — Egg chambers in midrib of cane leaf, slightly enlarged. Fig. 2. — Eggs, greatly enlarged. Fig. 3. — First-stage nymph. Fig. 4. — Second- stage nymph. Fig. 5. — Third-stage nymph. Fig. 6. — Fourth- stage nymph. Fig. 7. — Adult male 16 III. The Hawaiian sugar-cane leaf -roller (Omiodes accepta). Fig. 1. — Adult moth. Figs. 2, 3, 4, 5. — Larva? and details. Fig. 6. — Pupa and details. Fig. 7. — Apex of cremaster, showing the curled spines by which the pupa is fastened to the cocoon. Fig. 8. — Cluster of 4 eggs in groove on surface of leaf. Fig. 9. — Eggs more highly enlarged. Fig. ]0. — Leaf spun together for "retreat" or hiding place of caterpillar; shows where caterpillar has eaten. Fig. 11. — Leaf, showing spots where a very young caterpillar has eaten, leaving one epidermis intact, instead of eating holes through the leaf 42 IV. The sugar-cane mealy bug (Pseudococcus calceolaria;). Fig. 1. — Adult mealy-bugs clustered about the base of young cane. Fig. 2. — Adult female, twice natural size. Fig. 3. — A single adult female, with white mealy-like covering. Fig. 4. — Cocoons of male mealy-bug 44 TEXT FIGURES. Fig. 1. The sugar-cane leafhopper (Perlinsiclla saccharicida): Adult female. much enlarged; ovipositor, greatly enlarged 17 2. An apiary near a sugar-cane field 21 3. Yellow Caledonia sugar cane, a variety which is replacing Lahaina and Rose Bamboo in the Hawaiian Islands 24 4. The Hawaiian sugar-cane borer ([Sphenophorus] Rhabdocnemis obscurus): Eggs, larva?, pupa, cocoon, adult 35 5. The Hawaiian sugar-cane borer: Work in sugar cane 38 THE SUGAR-CANE INSECTS OF HAWAII. LOCATION AND CLIMATE OF THE HAWAIIAN ISLANDS. The mid-Pacific Territory of Hawaii (see Plate I) is situated 2,100 miles to the southwest from San Francisco, the California coast being the nearest continental area. The islands are separated by channels varying from 20 to 58 miles in width. The 8 inhabit- able islands, Hawaii, Maui, Oahu, Kauai, Molokai, Lanai, Kahoolawe, and Niihau, lie between 18° 54' and 22° 15' north latitude; that is, the northern hmit of the islands is just within the Tropics. The climate of the entire group is, however, only subtropical, due largely to the prevailing northeasterly trade winds, the cool ocean currents from the north, and the relatively low humidity. The temperature varies according to the altitude and the location of the land as regards the higher mountains. The formation of the islands is of recent volcanic nature, with the exception of the low-lying coastal plains, winch are of coral origin. The annual maximum temperature ranges from 88° to 90° F., while the annual minimum temperature recorded ranges from 52° to 58° F. A temperature of 29° F. has been recorded at an altitude of 6,685 feet, and freezing temperatures are of frequent occurrence at these high altitudes. The rainfall varies in amount with the locality. Places within a few miles of each other are known to differ more than 100 inches in average annual rainfall. The sides of the islands exposed to the northeast trade winds have abundant rains, while the opposite sides have little and some localities hardly any. The soils of the islands are exceedingly fertile and when properly cultivated yield abundant crops.' THE SUGAR INDUSTRY IN HAWAII. The production of sugar is the leading industry in the Hawaiian Islands. Sugar cane is grown on four of the islands. The island of Hawaii has the largest acreage devoted to cane, Oahu, Maui, and Kauai coming next in importance in the order named. There are more than 200,000 acres planted to cane in the islands. In 1908 521,000 tons of raw sugar were produced, having a value of more than $40,000,000. The average yield of sugar per acre is 44 tons. 83327°— Bull. 93—11 2 9 10 THE SUGAR-CANE INSECTS OF HAWAII. The plant crop is taken off 20 to 22 months from the time of plant- ing, and the first ratoon or stubble is harvested 18 to 20 months later. The second ratoon usually goes 18 months again before it is ground. Sometimes a "short ratoon" crop is made, in which case the cane runs about 14 months. The time given for growth depends on the maturity of the cane, which in turn is governed by the location and altitude of the land. To some extent also the time of harvest is governed by the labor supply, factory conveniences for taking off and grinding the crop, and the need of land for planting. The sugar industry in Hawaii was placed on a basis to insure its becoming the leading industry by the reciprocity treaty of 1876 between the United States and the Hawaiian Government, the latter at that time being an independent monarchy. The effect of this treaty in removing the duty on raw sugar exported to the United States was to increase American influence in the islands and to strengthen the commercial relations between the two countries. A second great factor m the development of the sugar industry was the annexation of the islands as a Territory of the United States by an act of Congress passed July 7, 1898, by mutual agreement between the two countries, Hawaii at that time having overthrown the mon- archy and become a republic. Annexation insured a free and pro- tected market to the sugar output of the islands and gave confidence for the investment of capital. This is of prime importance, as the production of sugar in the islands is on a corporation basis and any disturbance in the market is felt at once by every plantation in the Territory. Fundamental factors that have attended the development of the sugar industry are the equable climate of the islands, the natural productiveness of the soil, the resources of water for irrigation pur- poses, and the immunity from the more serious depredations by insects and diseases that retard the development of agricultural resources in less fortunate parts of the world. Further, there is to be found in Hawaii a class of progressive business men who have developed immense irrigation schemes, made use of the most modern agricultural and factory machinery, inaugurated advanced methods of cultivation, fertilization, and irrigation, and united their interests in a cooperative association. This organization, the Hawaiian Sugar Planters' Association, has, since April, 1895, maintained a private experiment station, where important researches have been made and valuable results obtained. The work has applied to varieties and seedhngs, propagation, culti- vation, irrigation, the use of fertihzers, and the manufacture of sugar. These investigations, together with the perfection of factory methods and field machinery, have brought the sugar industry of the islands to the high standard it holds among the sugar-producing countries of the world. THE SUGAR-CANE LEAFHOPPER 11 SUGAR-CANE INSECTS. The advent of a serious pest into the Hawaiian sugar-cane fields, the sugar-cane leafhopper {Perkinsiella saccharicida Kirk.), between 1900 and 1902 and the widespread injury of this insect throughout the sugar-cane districts in 1903 led to the establishment of an ento- mological division in the Sugar Planters' Experiment Station in September, 1904. In tins division detailed studies have been made of the species of insects occurring in the Hawaiian cane fields, the investigations relating particularly to the leafhopper and its natural enemies. Koebele a has earlier discussed the sugar-cane insects. Up to the time of the leafhopper invasion the sugar-cane borer ([Sphenophorus] RJiabdocnemis obscurus Boisd.) was the most injurious species. The sugar-cane aphis (ApMs saccJiari Zehntner), the sugar-cane mealy-bug (Pseudococcus calceolarise Maskell), the leaf -roller (Omiodes accepta Butler), cutworms, and certain other pests occurred locally, but up to this time no detailed study of their injury had been made. An insect enemy of sugar cane has exceptional advantages for development in the Hawaiian Islands. Approximately only one- half the total area is harvested at any one time. Thus the great extent of the plant gives an abundant supply of food, while the system of cropping provides a continuous supply. These conditions, together with the even climate, favor the uninterrupted breeding of any enemy of the plant. A further factor in the undue increase of the cane-feeding insects is the impetus to development arising from the absence of the special parasitic and predaceous enemies of the plant-feeding species. The absence of natural enemies is understood when it is known that the islands are isolated from all continental areas and that the economic plants are introduced forms for which the native flora has made way, carrying with it the endemic species of insects, while the insect enemies of a cultivated plant are of foreign origin, introduced into the islands with their host plant but without their natural enemies. These very facts, together with the almost total absence of secondary parasites as a group and the opportunity of eliminating them when introductions are made, furnish ideal conditions for the introduction and establishment of special parasitic insects. The greatest factor in the successful establishment of a special parasite is the absence of the secondary parasites of which it is the host. One can understand why emphasis has been placed on the use of natural enemies in the control of injurious species in Hawaii and why also greater success has been a Hawaiian Planters' Monthly, vol. 15, no. 12, pp. 590-598, December, 1896; vol. 17, nos. 5 and 6, pp. 208-219 and 258-269, May and June, 1898; vol. 18, no. 12, pp. 576-578, December, 1899; vol. 19, no. 11, pp. 519-524, November, 1900. 12 THE BUGAB-CANE [NSECTS OF HAWAII. attained in Hawaii than in continental regions where investigations of this character are under way. From the above remarks it is apparent that the entomologists of the Hawaiian Sugar Planters' Experiment Station are justified in placing emphasis on this phase of insect control. Indeed, their work has been almost entirely along this line. THE SUGAR-CANE LEAFHOPPER. (Perkinsiella saccharicida Kirk.) DISTRIBUTION. The Hawaiian sugar-cane leaf hopper (Perkinsiella saccltaricida Kirkaldy) was introduced into the islands some time prior to 1900 from Queensland, Australia. The species occurs throughout the. sugar-cane areas both in Australia and in Hawaii and has been recorded from Java. a APPEARANCE OF THE LEAFHOPPER IX HAWAIIAN CANE FIELDS. The first appearance of the leafhopper in Hawaii is recorded by Mr. Albert Koebele in January, 1902. 6 Koebele notes the species under the heading "Leafhopper (Fulgoridae)," the species at that time not having been described. Regarding its appearance Mr. Koebele says: According to Mr. Clark a small homopterous insect appeared upon the BUgar cane at the experimental station some twelve months since, affecting the Demerara and Rose Bamboo plants. Its presence is easily seen by the black and dirty appearance of the leaves and more or less red midribs. The insect lives in company with its larva in large numbers behind leaf sheaths, which it punctures to imbibe the sap of the plant. When mature it is exceedingly active in its habits, springing with suddenness from its resting place at the least dis- turbance. The eggs are oviposited into the midrib over a large extent, most numerous near the base, in groups of about from four to seven, and large quantities are often present in a single leaf. The surroundings of the sting become red and in advanced stages the whole of the midrib becomes more or less of this color and brownish red. That the species caused little alarm at this time is indicated by Mr. Koebele's further statement in this same article. He says: Should this insect become numerous on any plantation, they could be kept in check by careful and repeated stripping and burning, immediately after, of the leaves containing the eggs. I do not anticipate any serious results from the above insect, which may have been present upon the island for many years. In May, 1902, Dr. R. C. L. Perkins under the title "Leafhoppers (Fulgoridae)," in a report to Mr. C. F. Eckart, director of the Hawaiian a Kirkaldy, G. W. — A note on certain widely distributed leafhoppers. , and the latter, after a strong stand for many years, is now being rapidly succeeded by the more vigorous Yellow Caledonia. This cane with its upright growth and deep routing propensities has proved a most valuable acquisition in wet and dry localities alike. Growing erect, with a natural tendency to shed its dried leaves, it becomes an admirable cane for rainy districts, where varieties that are prone to fall to the ground and remain in contact with a frequently saturated soil have shown extreme a Eckart, C. F. — Varieties of cane. s satisfac- tory than would be the other method, is nevertheless simple, and does not call for much expenditure of time, nor for skilled labor. The one thing necessary to be posi- tively ascertained is that the spot whence the cuttings for distribution are taken is well supplied with all the kinds of parasites that it is desired to establish in new fields. It is now well known to us that all these destroyers are not yet established in all parts of all plantations, and therefore at present unless an entomologist previously test samples from the spot, whence distribution is to be made, it is quite likely that some of the most valuable parasites will not be taken to the new fields. If a sample be submitted to the entomologists, it can be passed as fit to supply all necessary parasites to new fields, or if not, cages of the deficient species can always be supplied from the cane in the grounds of the Experiment Station in Honolulu. As the parasites are continually spreading and increasing, such expert examination will at the most be necessary for a year or two; for it is perfectly certain that by that time all the species will be so gen- eral that it will be quite impossible to take any extensive sample of cane-leaves that bear egg? of leaf -hopper, which will not contain all . Such in fact is now the case in the cane at the Experiment Station. To sum up, the clearing of all cane from large acre- age- is a decided obstacle to the complete success of natural enemies of leaf-hopper, and the burning of trash aggravates the difficulty. As an offset to these conditions new fields should be supplied artificially with natural enemies, and they should be supplied as soon as any leaf-hoppers enter them. Of course future observation may prove this distribution unnecessary, but for the present it should be adopted. RELATED SPECIES. The Hawaiian sugar-cane leafhopper does not occur on the mainland of the United States. The insect is closely related to the corn leaf- hopper (Dicranotrojris maidis Ashm.), common on corn in the South- ern States. a A West Indian species of leafhopper is recorded as inju- rious to sugar-cane, by Westwood, in 1841, under the name Delphax saccharivora and is a member of the same family of insects as the Hawaiian sugar-cane and the corn leafhoppers. 6 Three further spe- cies of this same family, the Fulgorida?, are recorded as sugar-cane pests in Java by W. van Deventer. c o Quaintaxce, A. L.— Fla. Agr. Exp. Sta., Bui. 45, 1898. b Westwood, J. 0.— Mag. Nat. Hist., vol. 6. p. 407. 1841. c Phenice maculosa, Dicranotropis vastatrix, and Eumetopinn hrugt ri. Van Deventer, Handboek ten dienste van de Suikerriet-cultuur en de Rietsuiker-Fabricage op Java II. De Dierlijke vijanden van het Suikerriet en hunne Parasieten. Amsterdam, pp. 167-169, 1906. THE HAWAIIAN SUGAR-CANE BORER. 35 THE HAWAIIAN SUGAR-CANE BORER. ' ([Sphenophorus] Rhabdocnemis obscurus Boisd.) GEXERAL CHARACTERISTICS. The sue-ar-cane "borer" ([Sphenophorus] Rhabdocnemis obscurus Boisd.) (fig. 4) , infesting the cane stalk in Hawaii is the grub of a beetle belonging to the weevil family Calandridae. The sugar-cane stalk- borer of the southern United States is the caterpillar of a moth, Fig. 4. — The Hawaiian sugar-cane borer ([Sphenophorus] Rhabdocnemis obscurus): 1, Eggs, natural size. 2, Eggs in situ, much enlarged: a, Section of egg passage with egg, c; b, egg placed unusually near the rind, d. S, Larvae, just hatched and older, natural size. .1, Full-grawn larva, natural size. 5, Larva, side view, enlarged : a, Spiracles; b, cervical shield. 6, Larva, front view, enlarged. 7, Pupa, enlarged; a, Rostrum or beak; b, antenna; c, elytron or wing cover; d, folded wing. 8, Pupal case or cocoon, enlarged. 9, Adult, enlarged. (After Terry.) Diatrsea saccharalis Fab. Entomologically the two species are widely separated, belonging to entirely different orders of insects, but in the character of their injury to the cane stalk these two insects are quite similar — that is, they both develop within the cane stalk, and 36 THE SUGAR-CANE INSECTS OF HAWAII. by feeding on the interior cause great destruction to the plant. Com- paratively, the Hawaiian borer is more destructive and, because of the habits of the adult, a more persistent species to combat. The adult beetle of the Hawaiian borer is a stronger flyer than the adult moth of the mainland borer and therefore has a wider range over anv infested territory. As the adult of the Hawaiian borer, too, can emerge from any reasonable depth when buried in the soil, this renders the question of infested seed cane a serious one in Hawaii, while on the mainland the careful covering of infested seed cane is effective in preventing the emergence of the adult moth. These points are mentioned to bring out the fact that we are discussing here a species in no way related to the cane borer of the Southern States and in many ways not subject to the same means of control. [S phenophorus] Metamasius sericeus Oliv. is a species injurious to cane in the West Indies, being recorded from Jamaica, Barbadoes, St. Kitts, Antigua, St. Lucia, and British Guiana. In Porto Rico S phenophorus sexguttatus Drury is recorded by Busck a as boring in the stalks of sugar cane. DISTRIBUTION. The sugar-cane borer of Hawaii is recorded also from Fiji, Xew Guinea, Xew Ireland, Tahiti, Queensland, and the Malay Archipelago and probably occurs pretty generally throughout the islands of the southern Pacific. OCCURRENCE IN HAWAII. This species is a pest of long standing in the islands. The insect is recorded from the Island of Oahu in 1885 by the Rev. Thomas Black- burn, 6 who found the species breeding in the stems of bananas in the mountains, and the files of the Bureau (then Division) of Entomology, record the receipt of the borer from the Hawaiian Islands, as early as 1888. c It is believed that the sugar-cane borer was introduced into the islands from Tahiti in the stems of the banana plant during the early communications between the Hawaiian Islands and those of the South Seas. Hon. H. P. Baldwin, of Puunene, Maui, informed the writer that to his personal knowledge the beetle was injurious to sugar cane in the vicinity of Lahaina, the ancient capital of the islands, as early as 1865. Aside from the banana plant and sugar cane, the beetle infests the coconut palm, the sago palm, the royal palm, the wine palm, (Cary- ota urens), and the papaia (Carica papaya). a TJ. S. Dept. Agr., Bur. Ent., Bui. 22, p. 89, 1900. & Blackburn, Rev. T., and Sharp, D. — Memoirs on the Coleoptera of the Hawaiian Islands.