' *b. Mepart?7;ent oj Agncuffurtf Office of ExpeTiment ^UthfU l^ibmfy^ reserve a^ s CONNECTICUT 4-3 Agricultural Experiment Station NEW HAVEN, CONN. BULLETIN 230 JUNE, 1921 ENTOMOLOGICAL SERIES, No, 29 THE GRASS-FEEDING FROG-HOPPER OR SPITTLE-BUG By Philip G arm ax Figure 17. Spittle balls containing nymphs on grass stems CONTEXTS Page Officers and Staff of Station . . 326 The Grass-Feeding Frog-Hop- per or Spittle-Bug 327 History 327 The Egg 328 Table Giving Data on Length of Egg Stage 328 The Nymph 329 Pape- Habits of the Nymph ,. 330 Composition of the Froth 331 The Adult 331 Description of the Different Stages 332 Control iSIeasures 333 Summarj- 334 Literature 334 The Bulletins of this Station are mailed free to citizens of Connecticut who apply for them, and to others as far as the edition permits. CONNECTICUT AGRICULTURAL EXPERIMENT STATION OFFICERS AND STAFF June, 1921. BOARD OF CONTROL. His Excellency, Everett J. Lake, ex-officio, President. James H. Webb, Vice President Hamden George A. Hopson, Secretary Mount Carmel E. H. Jenkins, Director and Treasurer New Haven Joseph W, Alsop Avon Charles R. Treat Orange Elijah Rogers Southington William H. Hall South Willington STAFF. Administration. E. H. Jenkins, Ph.D., Director and Treasurer. Miss V. E. Cole, Librarian and Stenographer. Miss L. M. Beautlecht, Bookkeeper and Stenographer. Miss J. V. Berger, Stenographer. William Veitch, In charge of Buildings and Grounds. Chemistry. Analytical Laboratory. E. Monroe Bailey, Ph.D., Chemist in Charge. R. E. Andrew, M.A., C. E. Shepakd, -i H. D. Edmond, B.S., Owen L. Nolan, } Assistant Chemists. R. T. Mer-win, J Frank Sheldon, Laboratory Assistant. V. L. Churchill, Sampling Agent. Miss Alta H. Moss, Clerk. T. B. Osborne, Ph.D., D.Sc, Chemist in Charge. G. P. Clinton, Sc.D., Botanist. E. M. Stoddard, B.S., Assistant Botanist. Miss Florence A. McCormi^k, Ph.D., Scientific Assistant. G. E. Graham, General Assistant. Mrs. "W. W. Kelsbt, Stenographer. Protein Research. Botany. Entomology. Forostrj. Plant Breeding. W. E. Britton, Ph.D., Entomologist; State Entomologist. B. H. Walden, B.Agr., M. P. Zappe, B.S., \ Assistant Philip Garman, Ph.D., > Entomologists. John T. Ashworth, Deputy in Charge of Gipsy Moth Work. Samuel T. Sealt, Deputy in Charge of Mosquito Control. Miss Gladys M. Finley, Stenographer. Walter O. Filley, Forester A. E. Moss, M.F., Assistant. H. W. HicocK, M.F., Assistant. Miss Pauline A. Merchant, Stenographer . Donald F. Jon'es, S.D., Plant Breeder. P. C. Mangelsdorf, Assistant. Press op The Wilson H. Lee Comp.iny. The Grass-Feeding Frog-Hopper or Spittle-Bug • {Philaenus Uneatus Linnaeus) Order Hemiptera Family Cercopidae By Philip Garman, Ph.D. Frog-hopper or spittle-bug balls are often observed on shrubbery or herbaceous plants, in waste or uncultivated fields. Those of the grass-feeding species are especially noticeable in meadows and may cause persons not acquainted with them to speculate — often blindly — concerning their probable nature. Such speculations are mainly confined to the belief in "frog-spit" and "snake-spit," though occasionally we find people who think them the young of grasshoppers. The term "frog-hopper," which has grown out of the unfounded belief that spittle balls are voided by tree-frogs, is not inappropriate when applied to the adult bug because of its squat appearance and hopping ability. In favorable locations frog-hoppers may become abundant and no doubt do considerable damage. In one instance the writer counted fourteen balls on grass plants within a square foot, which shows the relative abundance of frog-hoppers under some condi- tions. About New Haven they do not become sufficiently numerous to do serious damage, but they contribute to the sum total of injury caused by leaf -hoppers, grasshoppers and thrips, and may be counted a pest for this reason. Frog-hoppers are sucking insects which make use of the sap drawn from the plant, to form their protective spittle. Any withdrawal of sap in this way naturally weakens the plant, and the stem upon which the insect has fed may become stunted or may not produce seed. Orchard grass, timothy, red top and blue grass are infested in Connecticut, while Osborn^ reports it also from Canada blue grass in Maine. The adults likewise feed on grass shoots but apparently do not do as much damage as the nymphs. Those who have studied the life histories of American Cercopidae have not reported direct field observation of the egg stage, of any of them; nor have they followed these insects through their com- plete cycle from egg to egg or adult to adult. Some of the missing links in our chain of information have been observed for the grass-feeding spittle-bug and an effort has been made to follow it through its life cycle by observations in the field, insectary and laboratory. These facts are herein recorded. History Osborn^ studied the species of Maine Cercopidae and his observa- tions are of especial value. He says of the grass-feeding species 328 CONNECTICUT EXPERIMENT STATION BULLETIN 230. that it lives through the winter in the egg stage. The eggs hatch late in May or early in June, and the nymph passes through several stages (3-4) before the adult emerges. Adults were ob- tained in Maine the first part of July and probably mate there in August. Egg laying is extended over "some weeks in autumn." Ball in his summary of the life history of Cercopidae^ says that all species except one pass the winter in the egg stage. The Egg Confined in small wire cages placed over grass planted in flower pots, the adult bugs were induced to mate and lay eggs. The eggs are laid between the leaf and the main stem (Fig. 18, e), are usually placed diagonally to the stem, and within two or three inches of the ground. They are firmly attached to the plant, either to leaf or stem. As many as eleven have been found in one group but they are sometimes laid singly. Cage records indicate that four or five are usually deposited together. In 1920 eggs were obtained on the following dates from adult females brought from the field and mated in the insectary: — July 12, 16, 25, 29; August 2, 3, 5, 7, 8, 10, 11, 14, 15, 19, 21, 31; September 9, 12 and 20. In 1921 the first eggs were obtained July 7, but could probably have been obtained earlier judging from the time of adult emergence. In 1920 adults were mated July 1, but no eggs were obtained. Of the eggs obtained in 1920, those laid on July 19, 25, 29; August 5, 6, 7, 12, 14, 26; September 7, 9 and 17, hatched the following spring, the period of incubation varying from 228 to 281 days. Table Giving Data on the Length op the Egg Stage. Length of Eggs Laid Eggs Hatched Period (Days; July 19, 1920 April 26, 1921 281 July 25, 1920 May 6, 1921 275 July 29, 1920 April 27, 1921 272 August 5, 1920 April 30, 1921 268 August 5, 1920 April 27, 1921 265 August 5, 1920 April 27, 1921 265 August 8, 1920 April 25, 1921 260 August 7, 1920 April 30, 1921 266 August^, 1920 April 26, 1921 261 August 9, 1920 April 30, 1921 264 August 10, 1920 April 20-26, 1921 253-259 August 14, 1920 April 26, 1921 255 August 14, 1920 April 25, 1921 254 August 15, 1920 April 26, 1921 254 August 14, 1920 April 26, 1921 255 August 14, 1920 April 25, 1921 254 August 31, 1920 April 26, 1921 239 September 9, 1920 April 25, 1921 228 September 12, 1920 April 28, 1921 228 September 17, 1920 May 8, 1921 233 GRASS-FEEDING FROG-HOPPER OR SPITTLE-BUG. 329 It is interesting to note in addition to the fact that the incuba- tion period varied from 228-281 days in 1920-'21, that the eggs laid between July 19-September 17 hatched within a short time of one another. These eggs were all placed out of doors as soon as laid and brought to the insectary after frost. Furthermore, it was noted in field cages that all hatched about the same time in 1920; viz., April 20, and that young were first seen in the field about this time both in shaded and exposed situations. The Nymph The nymph passes through four instars, and the nj^mphal stage lasts about forty-five days, according to field observations. In 1920 spittle balls were observed from June 1 to August 13, though most of them disappeared about July 4. In 1921 n^inphs were present in field cages from April 20 to June 14. The average sum of the different stages obtained in the insectary totals twenty- eight days, and it seems probable that the usual period lies be- tween twenty-eight and forty-five days in this latitude, though possibly more, or less. The first stage nymphs hved in 1921 from — April 27 to May 10 13 days April 20 to May 3 13 days April 26 to May 11 15 days April 26 to May 10 15 days April 26 to May 11 15 days April 28 to May 11 13 days April 26 to May 11 15 days The mean hourly temperature in the insectarj^ during the period from April 26 to Maj^ll was 56° F; maximum 76°; minimum 45° F. During 19 hours of this period the temperature registered below 50° F. The second stage collected from the field in 1920 lived from: — June 8 to June 12 4 days June 8 to June 9 1 day. Data on this sta|-e are ver}' unsatisfactory. Two specimens in the third instar collected from the field in 1920 lived from June 8 to June 12, four days, but these also are unsatisfactoiy data. The fourth instar in 1920 lived from: — June 12 to June 20 . . , 8 days June 9 to June 20 11 days June 12 to June 18 6 daj^s June 8 to June 18 10 days June 8 to June 15 7 days Osborn reared this stage in Maine in 2-6 days. 330 CONNECTICUT EXPERIMENT STATION BULLETIN 230. In field cages, nymphs hatched about April 20, and the first adults were seen June 14. Insectary temperature during this period varied from 45° - 82° F. The mean hourly temperature during April (April 26 to May 1) was 60.1° F., during May, 57.1° F; and during June (1-14) 60.3° F. For about 60 hours of this period the temperature was below 50° F. Habits of the Nymph The newly emerged nymph has a yellow spot on each side of the abdomen. These spots probably mark the location of the spittle glands, the openings of which are on the seventh and eighth seg- ments. While some of the material for the spittle comes from the anal opening, a great part must come from these abdominal glands, the substance flowing beneath the abdomen where it is filled with air bubbles. The apparatus for filling the mass with air bubbles is curious and is connected with a special adaptation for supplying air to the insect itself. In young nymphs the ventral surface of the abdomen is covered with a film of gelatinous material, allowing a space beneath it which connects with the space between the flap-like plates of the terminal segments. Air is drawn beneath this film, the insect keeping the tip of the abdo- men above the surface when quiet. Spiracles connecting with air tubes are located on the ventral surface, between pleura and sterna and are covered by the film, in young specimens, and by a series of overlapping plates — extensions of the pleura — in older ones. The insect is enabled in this way to obtain a continual supply of air and at the same time remain submerged in the spittle. When the insect desires to expand the froth it sticks the abclomen above the spittle, encloses an air bubble within the two terminal flaps, brings it beneath the surface and forces it out. Some species, however, are able to work faster. Placing the tip of the abdomen near the surface of the spittle they roll the terminal flaps together rapidly, taking air in and expelling it beneath the surface of the spittle, at the same time moving the tip of the abdomen but little. Expansion of the froth with air serves to hide the nymph and makes excessive secretion unnecessary. During nymphal life the bug may construct several balls but there is usually little migra- tion after the first mass is formed. Moults take place within the froth and in the case of the grass-feeding frog-hopper, the adiilt also develops within where it hardens sufl&ciently to enable it to fly. Thus during nymphal life at least, the grass-feeding spittle- bug is protected from predaceous * and parasitic enemies and partly from adverse climatic conditions. Lack of moisture seems to prevent development of the younger stages which depend largel}^ on tender rapidly growing shoots as a food supply. The result is seen in their more frequent occurrence in low damp places than in higher well drained pastures. PLATE XVIII a. Spittle balls on grass About natural size Photo by Walden. b. Adult bug. Six times natural size. c. Eggs on grass. Eight times natural size. Photo by Walden. PLATE XIX a. Field with spittle-masses. Photo by Walden. A '■'. — U : ■■ ^^ ---.^i'rAv ■■■:■■ /.■■,, / 4^f M^ h^-^^\ - • /y' V-.- / ' ' !