ger to honey bees. To improve the situ- ation, the county supervisors and the growers agreed to finance jointly the services of an entomologist. His duties TO Control were to make surveys of popula- tions and recommend control measures a Weed to the growers, giving due considera- tion to the protection of bees. The sav- James K. Holloway, C. B. Huffaker ings in insecticides his advice made pos- sible exceeded his salary and expenses, and damage to beekeeping was prac- Over many square miles of western tically eliminated. range lands millions of pea-sized, As long as insecticides are used, bee bright, metallic-colored are de- poisoning probably will continue to be stroying a common weed that for years a problem. Although the bee industry has caused huge economic losses. is still absorbing greater losses from in- The weed, perforatum, secticide poisoning than it should, there has a number of common names. In is a growing spirit of cooperation be- California it is called Klamath weed tween growers and beekeepers. In because it was first reported, about that lies the best chance of solution. 1900, in northern California in the vicinity of the Klamath River. In many FRANK E. TODD is apiculturist in of the Western States it is sometimes charge of the Southwestern States Bee referred to as goat weed. The recog- Culture Laboratory of the Department nized common name in Europe, orig- of Agriculture in Tucson, Ariz. inal home of the weed, is St. Johnswort because, according to legend, it blooms S. E. MCGREGOR, apiculturist with on June 24, the day of St. John the the division of bee culture of the Bu- Baptist. reau of Entomology and Plant Quaran- It has invaded extensive temperate tine, has been in bee work since ig2§ regions throughout the world. It is con- in Texas, Arkansas, Louisiana, New sidered a noxious weed in the range York, Wisconsin, and Arizona, lands of Australia, New Zealand, Can- ada, and the United States. The in- fested areas in California are esti- mated at 400,000 acres. Oregon, Wash- ington, Idaho, Nevada, and Montana also have many thousands of infested acres. Klamath weed causes losses by dis- placing desirable range- plants. It is poisonous to livestock, but death as a result is rare. that eat much of it become scabby, sore-mouthed, and unthrifty. It causes the white parts of the skin to become photosensitive and, when exposed to sunlight, blisters form on the unpigmented skin areas. Cattle are more sensitive to it than sheep. In some localities in California the grasses dry rapidly in the spring, and the most abundant remaining green The drone fly closely mimics the honey bee plant is Klamath weed. In those local- in color, size, and actions. ities cattle are usually moved from the 135 136 Yearbook of Agriculture 1952 ranges before the condition arises. But a root borer, Agrilus hyp er ici. The on occasion unavoidable delays do oc- stipulation was made that feeding tests cur^ and the animals may then con- be made on sugar beet, flax, hemp, sume damaging quantities of the weed. sweetpotato, tobacco, and cotton. The ingested plant causes cattle to A project for the importation, test- become irritable so that they arc diffi- ing, and colonization of the three cult to corral; sometimes it is almost species was then set up by the Bureau impossible to load them into trucks and of Entomology and Plant Quarantine it may be necessary to confine them and and the University of California. give them other feed for a day or two, The war made it impossible to collect until the effects of feeding on the weed the insects in Europe. It was learned, wear on". though, that abundant material was Many attempts have been made to available in Australia and would be control the weed, a perennial, with transported to California by the United chemicals—borax, 2,4-D, and others. States Army Air Transport Command. But the materials are expensive and the The Australian Council for Scientific land to be treated is mostly extensive and Industrial Research offered to col- and inaccessible. lect and ship the material. Control of the weed by insects has Leaders in those activities were been under consideration for several Frank Wilson and Harry S. Smith. Wil- years. The general method was success- son was sent to southern Europe in ful in other countries, notably Aus- 1935 when the first shipments of the tralia, but its use in this country is a natural enemies of Hypericum perfora- recent development. turn from England to Australia failed The Commonwealth of Australia to progress satisfactorily. Wilson had first began a search for insect enemies been associated with the work in Eng- of St. Johnswort in 1920 in England. land and he continued it in France un- Early in 1935, after the insects im- til 1940. Professor Smith, who was ported from Britain proved apparently head of the division of biological con- unsuccessful in Australia, the search trol in the University of California un- was transferred to southern France. til his retirement in 1951, is regarded The early work in Europe comprised as one of the world's foremost propo- tests by starvation and breeding of nents of biological control. Ever since many insects on 42 species of economic the biological control of Klamath weed plants, representing 19 botanical fami- was advocated by Dr. R. J. Tillyard of lies, to determine whether the insects Australia in 1926 he followed the de- could feed and breed on them. velopments. In correspondence with At the satisfactory conclusion of the Dr. A. J. Nicholson of Australia in tests in Europe, the species that had 1944, Smith found that the biological shown neither feeding nor reproduc- control was beginning to make prog- tion upon the test plants in Europe ress. He then took the steps that led to were shipped to Australia. Before they the project between the University of could be liberated, however, additional California and the Department of tests had to be made on plants that had Agriculture. When the importations not been tested in Europe. began, James K. Holloway was put in About 8 years after two species of charge of the investigations. the leaf-feeding beetles, , were released in Australia, encouraging THE FIRST IMPORTATIONS were results were reported. Subsequently made in October 1944. The initial men at the University of California problem was to adjust the life cycles so who had watched the experiments with that they would be in phase with the great interest were authorized by the seasons of the Northern Hemisphere. Department of Agriculture to import The specimens of the root borer {Agri- Chrysolina hyperici, C. gemellata^ and lus hyperici) were received as mature Insects To Control a Weed larvae in roots. Some of them were re- inal releases of C gemellata had shown tarded in cold storage, but others were a remarkable increase, and from them forced to emerge upon arrival. Neither we collected 212,000 adult beetles, method proved satisfactory, and fur- which we placed in 52 new locations in ther importations were curtailed until 16 counties of California. Three other the work in Europe could be resumed. releases were made in Oregon and two The two species of Chrysolina were in Idaho. Initial releases of C. hyperici occasionally shipped as mature larvae, were made in Washington, Idaho, and which would emerge as adults upon ar- Montana in 1948 through the cooper- rival, feed, and enter summer dorman- ation of the State experiment stations. cy about 3 weeks later. Most of the The Forest Service joined the project shipments, however, consisted of sum- in 1949 in Oregon, Washington, Idaho, mer-dormant adults. Either way, the and Montana. In May of that year problem was to bring the adults out of 140,000 adult C. hyperici were col- aestivation into the egg-laying phase. lected and shipped to those areas in By subjecting the adults to fine sprays units of 5,000 each, making 28 new of water each day, a state similar to locations in the Northwest. normal winter moisture conditions was C. gemellata was so numerous and reproduced in the laboratory, and the widespread in California by 1950 that beetles came out of aestivation, mated, redistribution became a local problem. and began producing fertile eggs with- Perhaps 3 million adult beetles were in 2 to 3 weeks. collected and redistributed in May During the first year of importations, 1950- enough C. hyperici were received to The success of C. hyperici has been conduct the feeding tests. The tests limited. It has become established in were completed in May 1945. '^^ feed- other localities, but an increase com- ing had taken place on any of the test parable to that of C. gemellata has plants, and four colonies were released been restricted mainly to the coastal late in the season. mountains in California. In January 1946 the feeding tests The efifectiveness of the leaf-feeding with C. gemellata were completed. beetles in controlling Klamath weed Permission was obtained to release is associated with their life cycles 13,650 adults that were being retained and their weed host. The balance be- in quarantine. They were divided into tween the propagative ability of the two colonies of 5,000 each, one colony weed and that of its insect enemy is of 2,000, and one of 1,650. determined by factors of soil condition, The experimental releases of both climate, and the influences of inter- species were made in the Coastal related plants and animals. Range, northern Sacramento River The two species of weed-feeding Valley, and the Sierra foothills—local- beetles differ slightly in their environ- ities considered representative of the mental requirements. Yet that small grazing areas in which the weed occurs difiFerence means that one species re- in California. produces abundantly and the other's A total of 330,000 adults of C. hy- reproduction is curtailed under Cali- perici, shipped from Australia, was re- fornia conditions. leased in 1947 at 66 sites in 15 counties C. gemellata starts reproducing of California. Two experimental col- quickly when the fall rains come. Con- onies of 5,000 each were released in sequently its progeny have enough time Oregon through the cooperation of the to make the necessary growth before Oregon Agricultural Experiment Sta- the dry season arrives in late spring and tion. early summer—conditions that are haz- Both species of Chrysolina were well ardous to pupal development. Also, the established by 1948, and we did not egg-laying period is longer, and greater need to import more. Two of the orig- numbers of eggs are deposited. 138 Yearbook of Agriculture 1952 But C, hyperici reacts slowly to moist From then on the weed suffers pro- conditions in the fall and under aver- gressive destruction of its foliage by the age California conditions deposits most larvae. The fully mature larvae enter of its eggs so late that there is insuffi- the soil to pupate at about the time the cient time to complete the necessary plant begins to develop the shoots that phases of development before dry become the flower-bearing stalks. The weather sets in. appearance of the adult beetles com- The life history of the more success- pletes a single cycle, which covers a ful species is attuned to the phases of year. weed growth and to local climatic con- The beetles can move in effective ditions. The adult beetles issue from numbers into new areas, but enough their pupal cells just beneath the sur- of both sexes must be present to assure face of the soil in April and early May. fertility of the eggs. About 3 years gen- They feed voraciously during May and erally are required to give local control June on the foliage of the plants, which in a remote area where only a few thou- then are flowering. By late June and sand beetles have been released. In the early July the beetles have completed third reproductive year the numbers preparation, by feeding and sunning, reach a level at which they can exert for their summer sleep. This inactive, controlling pressure on the weed. dry-season stage is spent beneath de- Local dispersion is normally accom- bris, under small stones, and in crevices plished by the crawling adult beetles, of the soil. w^hich often are seen moving in great The beetles spend 4 to 6 months in numbers across roads or ravines from this inactive condition without food or centers of overpopulation where the water. During this period the weed, w^ecd has been cleared. Dispersion by too, enters a relatively dormant phase. flight is less commonly observed but oc- It develops and ripens its seed crop but curs under conditions of high drops most of its leaves and becomes density, complete depletion of the food hard and w^oody. supply, and hot, sunny w^eather. Col- The larvae feed actively in warm onies have appeared which apparently periods in winter and spring. Their in- are the results of single or repeated tensive feeding keeps the plant stripped flights from production centers as far of leaves over a long period w^hen its as 3 miles distant. food reserves are at a low ebb. Thus Through its natural powers of dis- the root system and the plant die of persion, plus a supplemental influence starvation. Adult feeding, voracious as from establishment of secondary initial it is, does not last long enough to pro- colonies in the area, C. gemellata has duce wholesale death of the plants now spread and effected general con- without the previous feeding by the trol of the w^eed over hundreds of larvae. square miles in southern Humboldt The rains in fall and early winter re- County, California. activate weed and beetle. The weed The same species has cleared an sends out vigorous, prostrate, leafy open range area in Placer County and shoots in rosettes at the base of the moved from that limited infestation flowering stalks. The beetles mate, and through small, isolated patches of weed many eggs are placed on the leafy to points up to 3 miles away in various growth. The larvae from the eggs and directions. No additional releases were the host weed grow during the winter made anywhere in the area. A second in relation to the temperatures. All and younger colony in Placer County stages of the beetles can survive heavy was located in an area notably unfa- snows and cold. By midwinter and vorable as to climate, yet it cleared that early spring in favorable locations the field of the weed within 3 years. larvae reach a half-grown to nearly C. hyperici, though poorly adapted mature grub stage. to the California conditions generally, Insects To Control a Weed 139 brought under control 4 to 5 square vent the return of the weed in such miles in an upland area of Humboldt fields under proper grazing manage- County, where retention of soil mois- ment. ture late in the season has operated to Several investigators believe that it? advantage. three-fourths of the land south of Ranchers and farm workers attest to Mount Shasta and from the coast the complete destruction of the weed to the Sierra foothills in California by the beetles. They have seen how the was originally covered with perennial hungry insects have removed the weed bunchgrasses. Annual plants now make from a large area near Blocksburg, up most of the forage there. Their re- Calif. placements by perennials would be im- The beetles also can locate and de- possible ( and not necessarily desirable) stroy small, isolated stands of weeds everywhere in the region. that were missed in previous years. The It therefore seems probable that appearance of the seedling weeds in with the destruction of Klamath weed cleared fields is common, but so far the predominant annual-plant cover enough beetles are present in the area characteristic of the region may re- to find them. These scattered reinfes- gain the land under normal conditions. tation spots and plants in the edges of That has happened in the areas where heavily wooded borders (less preferred the weed has been cleared for three by the beetles) maintain the general successive seasons. In Placer County, distribution of the beetles in an area annual grasses, dominated by soft chess after the weeds cease to be a range (Bromus hordeaceus), legumes such as problem. That fact may assure the re- birdsfoot trefoil, clovers, and lupines, turn of the beetles in eíTective numbers and desirable forbs such as filaree, have quickly enough to take care of rcin- returned as thickly as they are in neigh- festations before they can reach seri- boring range lands that have remained ous proportions. free of Klamath weed. The success of the beetles in Hum- THE CONTROL OF A WEED by the bi- boldt County is attended by circum- ological method involves several as- stances favorable to return of a forage pects of ecology. Klamath weed is pri- cover of maximum value. In the areas marily a pest in range areas where soil most heavily infested with the weed moisture is ample from winter to early (indicative of a favorable soil and summer but deficient later in the year. site), the main perennial bunchgrass Overgrazing fosters its spread. Under of earlier years {Danthonia calif or- such conditions, its deep root system nica) has managed to survive along enables it to overcome even the stur- trails and about the edges of diest grass competitors, particularly seepage areas, which were too wet for when grazing has been so heavy that Klamath weed in winter. The destruc- seed production by the more vigorous tion of the dense stands of the aggres- perennial grasses is curtailed. sive weed has permitted a gradual re- An insect may control weeds by more turn of this fine range plant. Although subtle means than direct destruction. its distribution in the original beetle- If its action is such as to remove the release remained spotty for somiC years, competitive advantage of the weed it soon began to develop a vigorous host over desirable plant species, the cover that spread slowly over new weed may then be overcome by plants ground. that cannot alone compete with it. At the end of a 50-acre field that That does not explain the control of had been cleared of weed by the beetles Klamath weed, but the pressure of the for 3 years, a rather complete stand of beetles on the weed at a time when the hardy bunchgrass developed. Over vigorous competing range plants oc- the whole field—most of which had cupy the area may be enough to pre- been weed-free only 2 years—Dan- 140 Yearbook of Agriculture 1952 thonia increased from 9.2 percent of the population complexes of insects and the total plant cover in 1947 to 23.4 the weeds attacked by them as com- percent in 1950. By considering soft ponents of a natural range environ- chess {Bromus hordeaceus), Dantho- ment. Dr. Hußaker holds degrees from nia, and desirable legumes together, the University of Tennessee and Ohio one gets a general picture of the total State University. forage improvement due to the beetle action. The three desirable types in- The authors suggest for further reading creased from 14.8 percent in 1947 to Bio-Ecology by Frederic E. Clements and 43.4 percent in 1950. Klamath weed Victor E. Shelford, published by John Wiley & Sons, Inc., in 1939, and the following was reduced from predominance (57.6 publications: percent) to complete absence. Thus Australian Council for Scientific and In- the position of the weed and the posi- dustrial Research—Bulletin iSg, The En- tion of the three desirable plants was tomological Control of St. John's Wort (Hy- pericum perforatum L.) . . ., by Frank Wil- practically reversed. son, 1943; and Pamphlet 29^ The Possibility The Chrysolina beetles have become of the Entomological Control of St. John's a permanent part of the natural fauna. Wort in Australia—Progress Report, by G. Their future success will depend mostly A. Currie and S. Garthside, 1932. on how closely the life processes of the California Agricultural Experiment Sta- beetles and their host coincide with tion Bulletins—6/5, The Chemical Control changes in weather, for on that syn- of St. Johnswort, by R. N. Raynor^ ^937» chronization depends how fast the and 5033 St. Johnswort on Range Lands of California, by Arthur W, Sampson and Ken- beetles multiply and how intensive is neth W. Parker, 1930. their action on uninvaded weed stands California Forest and Range Experiment and reinfested fields. Station Technical Note 21, Standards for Indications are that the beetles can Judging the Degree of Forage Utilization on duplicate throughout the Northwest California Annual-Type. Ranges, by A. L. the success they have had in California. Hormay and A. Fausett, 1942. It would be an economical, self-per- In Ecology, The Return of Native Per- ennial Bunchgrass Following the Removal petuating way to combat a serious pest, of Klamath Weed {) now that the first intensive research and L.) by Imported Beetles, by C. B. Huffaker^ exhaustive explorations are completed. volume 32, pages 443-438, 1951. In the Journal of Economic Entomology, JAMES K. HOLLOW AY is an entomol- The Role of Chrysolina gemellata in the ogist in the Bureau of Entomology and Biological Control of Klamath Weed, by Plant Quarantine, the division of for- J. K. Holloway and C. B. Huffaker, vol- eign parasite introduction, and special- ume 44, pages 244-247, 1951. In the Proceedings of the Entomologie cd ist in biological control in the Univer- Society of Washington, Biological Control sity of California College of Agricul- of Weeds in the United States, by H. S, ture. He has been engaged in research Smith, volume 49, number 6, pages 169— in biological control since ig2y and has no> 194:7- had responsibility for carrying forward the project on the biological control of Klamath weed in this country since its inception in 1944. He studied at Missis- sippi State College and Ohio State University. C. B. HuFFAKER, an entomologist and ecologist, has been engaged in eco- ■^i[T\^ logical research since ig40. In 1046 he was appointed assistant entomolo- gist in the division of biological control of the University of California, where he has been particularly interested in Mexican bean beetle larva.