f 7. :>".-;£ J March 26, 1M11. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY— CIRCULAR No. 135. L. O. HOWARD, Entomologist and Chief of Bureau. THE ASPARAGUS MINER. F. II. CHITTENDEN, Sc. I>.. In ( harge of Truck Crop and Ston d Product I ■ stigations. 79779°— U WASHINGTON : GOVERNMENT PRINTING OFFICE I IB1I U.S. DEPi B UREA U OF EX TOM" LOG Y. L. 0. Howard, Entomologist and Chief of Bureau. C. L. Mablatt. 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. Hunteb. 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 cub D. M. Rogers, in charge of preventing spread of moths, field work. Rolla P. Ccbbie, in charge of editorial wort. Mabel Colcoed, librarian. Tecck Ceop and Stobed Pboduct Insect Investigations. F. H. 'hittenden. in charge. H. M. Russell. G. H. Popenoe. D. K. McMillan. E. G. Smyth. Thos. H. Jones. M. M. High. Feed. A. Johnston. Wm. B. Parker. H. 0. Marsh, agents and experts. I. J. Condit. collaborator in Califon P. T. Cole, collaborator in tidewater Virginia. CIRCULAR NO. 135. Issued March 25, 1611. United States Department of Agriculture, BUREAU OF ENTOMOLOGY. L. O. HOWARD, Entomologist and Chief of Bureau. THE ASPARAGUS MINER.' {Agromyza simplex Loew.) By 1' II < mi ii \m \. Sc. 1' , In Charge of Truck Crop and Stored Product Insect Investigations. The stalks of asparagus are frequently attacked by insects, ami in recent years have boon report ed considerably injured by the larva or maggot of a minute Mack fly to which the name asparagus miner has beengiven. The larva mines beneath the epidermis of the stalk, ami when it has t ransl'ormed to the puparium or "flaxseed' 1 stage the thin outer skin hecomes more or less ruptured and the presence of the insect is easily detected. It operates more abundantly near the base Fig. 1.— The asparagus miner (Agromyza simplex): Fly. dorsal view at left, lateral view at ripht. Highly magnified. (Author's Illustration of the stalks and penetrates below the surface of the ground t<> a depth of 7 m- s inches. During the year I '.Kid this species attracted considerable attention by its abundance in some of the principal asparagus-grovi ing seel ions of New England and it bids fair to become a pest of considerable importance. It was first noticed on asparagus in 1896, prior to which time nothing was known of its habits. It isa native species and evidently restricted to asparagus as a food plant. Until the year L906 it had not been recognized as doing injury to cutting beds, although attack had been observed in various sections. a Revised reprint from Bui. 6G, n. ^., Bur. Em., U. S. Dept. A 79779°— CU". 135-11 1 THE ASPARAGUS MINER. The mines of the larvae about and below the bases of the stalks are frequently so abundant that they have the effect of girdling, so that the injured stalks can readily be pulled from the ground. DESCRIPTIVE. The parent insect is a two- winged fly (fig. 1), metallic black, with large prominent head and eyes, and clear wings, the wing expanse being about one-sixth of an inch (4 mm.). The larva (fig. 2, a) is about one-fifth of an inch long and milk- white in color. Like other maggots, it is footless, large at the posterior extremity, and tapering toward the head. The puparium (fig. 2, d, e) is not unlike the "flaxseed" of the perni- cious Hessian fly, with which it has been aptly compared. At a little distance, also, it suggests a Lecanium scale. This stage is remarkable be- cause of its peculiar flattened and curved position, as seen from the side. It is red in color, and meas- ures about 3.5 mm. in length and about 1 mm. in width. The egg has not been observed. This species belongs to the dipter- ous family Agromyzidae, and was described by Loew in 1861,° the locality being given as "Middle States." DISTRIBUTION. In its injurious occurrences this species appears to be limited to the eastern United States, from New England to Tennessee. From avail- able data it is quite obvious, however, that it may be destructive over a considerable territory, including a large portion of Massachusetts and Connecticut, Long Island, the District of Columbia, Pennsyl- vania, and Tennessee. As it is recorded from New Jersey, it is prob- ably injurious there, although no reports of injury in that State have reached this office. In time it will doubtless attract attention in intermediate points and in States farther north and west. It has also appeared in asparagus beds in California. HISTORICAL AND BIOLOGICAL NOTES. In May, 1897, and afterwards this fly was observed in abundance by the writer on terminal shoots of asparagus, particularly at Cabin John, Md. Two weeks later no more flies were seen, but June 26 Fig. 2.— The asparagus miner (Agromyza sim- plex): a, Larva, lateral view; b, thoracic spir- acles; c, anal spiracles; d, puparium from side; e, same from above; /, section of asparagus stalk, showing injury and location of puparia on detached section, a-e, Much enlarged: /, slightly reduced. (Author's illustration.) a Diptera Americse eeptentrionalie indigena, Centuria octava 84, p. 160. THK ASPARAGUS MI NEK. 6 they reappeared and were then usually seen in copula. It was sur- mised ai the time that this second appearance indicated the Brsl new generation of the year and its abundance on asparagus seemed to show that it lived in some manner at t he expense of thai plant . Examina- tion of asparagus plants at that time, howev er, Failed to show at tack. In 1900 complaints of injuries were made in the 1 >istrict of Colum- bia, aud at Know die, Tenn.. and in the meantime the species came under the observation of Mr. 1''. A. Sirrine, who stated'' that work was lirst observed in asparagus fields on Long Island in L896. Late in September, 1900, word was received of injury to asparagus from Tennallytown, I). C. When the writer visited the held, although injury was apparent on the outer skin of some st;dk>. no living specimens could he ohtained, only the dried pup aria being in e\ idence at that time. October 2 of the same year, Mr. Samuel M. Baiu, Qniversitj of Tennessee, Know die, Tenn., sent a stalk of asparagus showing the work of this miner upon the skin, and, October 27, specimens of the dried puparia. February IS, 1001, it was reported at Philadelphia, Pa., that this insect seemed to cause much greater trouble than the common asparagus beetle. Two or three new beds of asparagus were lost on account of its ravages. By the writer's direction, Mr. F. C. Pratt visited a truck farm at Brookland, I). ('., where asparagus was one of the main crops, June 18, 1902. Asparagus was still being cut for market, but volunteer plants were growing here and there in fields of corn, cantaloupe, and potatoes, between rows. A few flies were seen on terminal shoots of asparagus that showed wilting, ami many volunteer plant- were badly infested, most individuals having transformed to pupse. Although stems break oil' jusl below the ground, the entire colony of insects below that point is left with sullicient moisture and nourish- ment for their maintenance. The puparia were presenl in great numbers underneath the outer skin of the root, and as many as nine puparia were counted in a space only an inch long on one stalk. The stalks below the point of injurv appeared to be perfectly sound. Larva' also were found in rotting stalks that broke off just below ground. During September, 1906, Messrs. J. B. Norton and A. 1). Shamel, of the Bureau of Plant Industry, furnished stems of asparagus from Concord, Mass.. showing severe infestation by this species, many puparia being presenl under the mined outer skin. In the neighbor- hood of Concord, a very important asparagus-growing region where hundreds of acres are devoted to this crop, infestation was practi- cally absolute, the insect being as abundant as the common asparagus "Bui. 10, n. *., Div. Km . I" S. Dept. Agric, p. 62, 1898. &Bul. 180, X. V. Agric. Exp. Sta., p. J77, Geneva, 1900. 4 THE ASPARAGUS MINER. beetle, and present wherever rust was found, as also where no rust was present. Some plants showed injury 7 inches below the surface. Later Mr. Shamel reported finding infestation in every field and patch of asparagus which he visited in Massachusetts and Connect- icut, particularly at Suffield, Granby, and Hartford. Conn., and he believed attack to be widespread." October 26, 1006, Mr. Ralph E. Smith wrote that the conditions under which this asparagus miner was found in abundance in the yellow stalks of asparagus in California, as reported by him in an article on Asparagus Rust Control, b had prevailed for two or three years. The insect was always very abundant at the base of yellow, dying stalks, although injury was attributed to the "centipede," reported as wireworms on a previous occasion. The asparagus miner was reported by Mr. I. J. Condit in the vicinity of Antioch, Cal., August 10, 1008, where the common asparagus beetle was also abundant. The miner was equally numerous and stalks showing infestation were received. The miner-infested stalks could generally be detected by their roughened appearance near the ground- This species was also taken at Oakley, and it seems probable that it is becoming generally distributed in California. In one place at Oakley Mr. Condit observed the miner cpiite common on some stalks. During October, 1008, the writer observed this species well estab- lished on asparagus in the vicinity of Portsmouth, Va. In October, also, very severe injury was reported to asparagus in the vicinity of Concord, Mass. The roots of the plants were not only girdled, but the miners worked up the stalks some inches above the ground. REMEDIAL MEASURES. With our present knowledge of the life economy of this species, two methods of control suggest themselves as of greatest value, and it may be that they will prove all that is necessary under ordinary conditions. (1) In spring permit a few volunteer asparagus plants to grow as a trap crop, to lure the fly from the main crop or the cutting beds for the deposition of her eggs. After this has been accomplished the trap crop should be destroyed by pulling the infested plants and burning them with their contained puparia. The time to pull the plants will vary according to locality and somewhat according to season also. The second and third week in June would be about the right time in and near the District of Columbia. On Long Island this work should be done a week or two later. In the northernmost °Its occurrence at New Haven, Conn., is recorded by W. E. Britton (Gth Kept. State Ent. Conn, for 1906, pp. 303-306, 1907). ^ Bui. 172, Univ. Cal. Agric. Exp. Sta., p. 21.