Agromyzidae Of Florida

The family Agromyzidae consists of small to minute flies whose larvae are stem, seed, and leaf miners of a wide assortment of plants. Some species may cause moderate to serious damage to plants of economic importance. In Florida leaf mining agromyzids have caused substantial economic loss in commercial fields of tomatoes and corn. Commercial plantings of melons, beans, and chrysanthemums in southern Florida may be significantly damaged by agromyzid leaf miners in some years. Many other crop plants, ornamentals and flowering annuals are damaged to a lesser extent in Florida. An ornamental plant widely used in landscaping, llex vomitoria, frequently is made so unsightly by agromyzid leaf miners as to be virtually unsaleable. The authors of this bulletin have stated that at least 150 species of Agromyzidae are known to feed on plants of economic importance.

Experimental work done over many years at Florida agricultural experiment stations to develop effective controls for agromyzid miners on various crops yielded erratic, inconsistent data which were puzzling to the investigators. The taxonomic, ecological, and life history studies over the past several years by Spencer and Stegmaier have provided an explanation for experimental and applied control studies which had produced confusing results. Their studies have shown that often what had been thought to be a single species attacking a wide variety of host plants actually was a complex of several species, some of which are highly specific to a particular group of plants. In some instances the species attacking a host plant in one p_art of Florida proved to be different from the species attacking the same host in another part of the state, and controls effective on one might prove to be ineffective against the other. The authors have noted that “Sudden mass outbreaks of leaf-mining i activity by relatively unknown species may occur at any time on plants which have not been known to suffer substantial damage … their potential to cause serious damage to a number of cultivated plants is ever present and, with favorable conditions, one or another species may at any time develop as a serious pest. . . . Damage from leaf-mining activity can be severe, frequently reaching destructive levels, or at least weakening younger plants and causing an appreciable reduction in crop yields.” A notable example is the alfalfa blotch-miner, Agromyza frontella (Rondani), a European species which, in its native land, has been of little economic importance. Introduced accidentally into the eastern United States a few years ago, this species, unchecked by its natural enemies, has rapidly developed into a major pest of alfalfa. Heavily infested fields of alfalfa appear almost whitish due to the heavy mining of the foliage by the alfalfa blotch-miner.

Prior to the work by Spencer and Stegmaier, less than a dozen species of agromyzids were recorded from Florida, and virtually all of those which produced a serpertine trail in foliage of various kinds of plants had been considered to be caused by a single species, Liriomyza pusilla (Meigen). As recently as 1959, Frick, in his synopsis of North American species, specifically mentioned only two species as occurring in Florida. More than 80 species of agromyzids now have been recorded from Florida by Spencer and Stegmaier. Liriomyza pusilla has not been found to occur in Florida! In fact it has been shown that this is a European species that does not even occur in North America.

Often there is a direct relationship between economic crops and some of their weed relatives. These weed plants may serve as reservoirs for the agromyzids which attack commercial crops and ornamentals, so that the control of these insect pests may involve the control of their weed hosts. Field studies by the junior author have shown that agromyzid populations have been maintained on weed hosts, although usually at lower levels, during seasons when preferred crop hosts were not being grown. Also related to this is the important consideration that parasites of the agromyzids may be maintained on agromyzid populations attacking weed hosts, whereas these parasites may be inadvertently destroyed in commercial crops by systematic spraying for control of agromyzids and other insect pests. Experimental work is needed to determine whether certain weeds are more harmful as reservoirs of agromyzid crop pests than beneficial as reservoirs for the parasites which attack the agromyzids.

A generalization can be made concerning the Agromyzidae and about problems which they cause that is true of many other groups of insects and the problems associated with them. In many ways Florida’s insect problems are unique. We in Florida cannot rely on the work done by investigators in other states to solve our problems to the same degree that is true in, say, Indiana, Illinois, or Ohio. Many of the economic insects which occur in Florida react differently here than in other areas where they occur. When farther north some might have only a single generation a year. Under Florida conditions, they may have two to several generations a year, with resulting differences in what would be required to control them. Length and timing of the life cycle of many species are different in Florida from what they are in other parts of the range of the species, and they may differ in one part of Florida from another. Florida’s insect fauna is derived in part from the more northern parts of the Nearctic Region and in part from the subtropical regions of Central America and the West Indies. As a result Florida often must solve its own problems with little reliance upon the work done in other states.

Basic information is still very meager for many groups of Florida arthropods. This was certainly true of the Agromyzidae until the studies made by Spencer and Stegmaier, ii which were partially supported by the Florida Department of Agriculture and Consumer Services. The need for a comprehensive reference dealing specifically with Florida agromyzids has become apparent to those concerned with the problems which they cause. Pertinent information relevant to Florida is virtually absent in the literature. The only recent extensive treatment of the Agromyzidae of any part of North America is Spencer’s 1969 bulletin on the Agromyzidae of Canada. This study, financed by the Canada Department of Agriculture, more than doubled the number of species known to occur in Canada and yielded considerable valuable data on host relationships, biology, and life histories. Since little of this is directly applicable to Florida, the prime need for this publication is obvious.

It is our hope that this bulletin will stimulate further careful studies of the Agromyzidae of Florida. Despite the good work done by Spencer and Stegmaier, much remains to be learned about leaf, stem, and seed mining agromyzids of our state, especially in the central and northern areas.

The senior author, Dr. Kenneth Angus Spencer, is the world’s foremost authority on the family Agromyzidae. Like many others who have made noteworthy contributions to arthropod taxonomy and have earned reputations as leading authorities on various groups, Spencer’s interest in insects began as an avocation rather than as a vocation. Born in Cheam, Surrey, England on 15 March 1916, he obtained his early education at Whitgift School, Croydon and later graduated with honors in German and French from London University. In September 1939 he volunteered for Field Service Corps as a Probationary Private, was commissioned in light infantry in 1940. From 1941 to 1945 he was attached to the Intelligence Corps and served at Divisional and Corps Headquarters in the Middle East, Italy and Germany. During 1945-7 he was a Political Adviser with the Military Government in Berlin with the rank of Major.

From 1948 through 1951 he held various short-term positions in education and translation, including some time in Greece with the United Nations Balkans Commission. From 1952 to 1957 he was employed as Export Manager by Crosfield Electronics Ltd., working with electronic controls for the printing industry. He was on the Board as Sales Director from 1957 through 1969. During this period he traveled throughout the world, appointing and controlling agents in some 30 countries.

During much of this period Spencer was developing as an avocation his interest in Agromyzidae, and during 1949-50 he translated from German into English Professor E. M. Hering’s famous work, Biology of Leaf Miners. From 1951 through 1969 he collected and studied Agromyzidae in Africa, India, Philippines, Ceylon, Australia, Brazil, Colombia, Canada, Florida and throughout Europe. During this period he published some 70 papers, including regional and generic revisions and finally a major bulletin, The Agromyzidae of Canada and Alaska. During 1966 he held a temporary appointment as Visiting Professor in the Department of Entomology, University f)f Alberta, Edmonton, and during 1966-67 he served as a Research Associate of the Canada Department of Agriculture, Ottawa. In 1968 he was appointed a Research Associate of the Florida State Collection of Arthropods, Gainesville. He is a member of several professional organizations including the British Entomological and Natural History Society and the Royal Entomological Society, London. During 1968-70 he presented seminars on Agromyzidae at the University of Florida, Harvard University, Cornell University Wayne State University, and the University of Alberta. He received the Doctor of Science degree in 1970 from London University and became attached to the Department of Entomology, Oxford with a Natural Environment Research Council grant to prepare an Identification Handbook of the British Agromyzidae. He recently completed a book on world species of Agromyzidae of economic importance and spent fhe weeks in Venezuela during April and May 1972 studying agromyzid pests of commercial crops.

The junior author, Carl Edward Stegmaier, Jr., like the senior author, began his interest in the Agromyzidae as an extracurricular activity on his personal time. For many years he has served as a Plant Quarantine Inspector with the U. S. Plant Quarantine Service in Miami, helping to safeguard the U. S. from the introduction of plant pests from foreign countries. During his off-duty hours, as a Research Associate of the Florida State Collection of Arthropods, Mr. Stegmaier has made extensive collections of leaf, stem, and seed mining Agromyzidae throughout all seasons in recent years, primarily in southern Florida. From many wild and domestic plant hosts he has made numerous rearings of agromyzids, keeping careful records of all of his findings. This bulletin is based in large part on the field and laboratory work done by Mr. Stegmaier, while the taxonomic work is primarily that of the senior author. Virtually all of our present knowledge of the life histories and of the parasites of Florida agromyzids is based upon the collections and rearings of Mr. Stegmaier.

Carl was born 18 January 1921 in Kansas City, Kansas. He attended Kansas Junior College during 1946-47, received his B. Sc. in Entomology from Kansas State University in 1949 and the M. Sc. in Entomology from the same university in 1950. He is a member of Gamma Sigma Delta honorary fraternity, Kansas Entomological Society, Florida Entomological Society, Georgia Entomological Society, and the Entomological Society of Washington. He served in the Medical Detachment, 161st Field Artillery, Kansas National Guard during 1938-40 and in the U. S. Marine Corps from 1940 to early 1946, receiving the Wake Island Expeditionary Medal and an Asiatic-Pacific Ribbon Presidential Unit Citation. He was captured on Wake Island, for 45 months was a Japanese prisoner of war, and eventually was discharged as a Disabled American Veteran. While a prisoner he studied the Japanese language, self taught, and was used as an interpreter to liberate Chinese prisoners on Hokkaido, Japan after the end of World War II. He is a Trustee of the Miami Museum of Science and Natural History, and during 1965-66 he served as Chairman of the Sub-tropical Branch of the Florida Entomological Society. For many years he has been an active Boy Scout counsellor. His current entomological interests cover all leaf, stem, and seed mining insects, their life history and ecology, and in recent years he has discovered many species new to Florida, new to North America, and new to science, notably in the orders Diptera, Lepidoptera, and Hymenoptera.