San Diego Floral Association
Growing Grounds from California Garden

© SAN DIEGO FLORAL ASSOCIATION and © John Blocker.
These stories may not be published in any form or copied onto another media without written permission from San Diego Floral Association.

Reprinted From: November/December 2010, Volume 101 No. 6

California’s citrus growers defeat a dangerous pest with the first biological control program
By John Blocker

They say the bugs, the dreadful bugs
Have other bugs to bite ’em;
And t’other bugs have smaller bugs
And so ad infinitum.

-Toast given by Hon. L. W. Buck of Vacaville at the grand banquet for the Eleventh Fruit Growers Convention of the State of California held in National City in 1889

In 1889 in National City, Flora Kimball welcomed the delegates to the Eleventh Fruit Growers Convention of the State of California. In her opening address she greeted the delegates “…not as horticulturalists alone, but as apostles of fruit, trees and flowers.” Her husband, Frank Kimball, was vice-president of the convention and a director-at-large to the State Board of Horticulture under whose auspices the convention was held. He acted as master of ceremonies for the grand banquet attended by more than 800 people at the closing of the convention. He also had a part interest in the company that was selling parcels of land in Chula Vista to persons interested in planting citrus groves.

Cottony cushion scale (Icerya purchasi) was at that time devastating citrus groves and ornamental plantings throughout California. President of the convention Ellwood Cooper of Santa Barbara warned the delegates in his opening address, “Much alarm was manifested on account of the ravages of the Icerya purchasi and information is wanted on how to best arrest the spread of this dangerous insect.”

How these early citrus farmers confronted and defeated this pest would be a first for the industry and earn one of the main researchers the title of the “Father of Biological Control.”

From Down Under

In 1887, at an earlier Fruit Growers Convention in Riverside, representatives of the fledgling citrus industry in California met with the Chief of the Division of Entomology for the United States Department of Agriculture, Charles Valentine Riley. They discussed the control of cottony cushion scale. California growers wanted the Federal government to send someone to the citrus groves near Adelaide, Australia, to search for the scale’s parasites and predators. They believed cottony cushion scale had arrived in Menlo Park on a shipment in 1868 of acacia from Australia.

In his speech to the Riverside convention, Riley agreed the scale was most likely native to either Australia or New Zealand. He stated he would not hesitate to send one of his field agents to Australia but, “…the mere suggestion that I wanted $1,500 to $2,000 for such a purpose would be more apt to cause laughter and ridicule on the part of the average committee in Congress than serious and earnest consideration.” Riley, working with the French government, had initiated a very successful control program for the grape phylloxera, an aphid-like insect that had been decimating French vineyards. Congress had specifically passed a law prohibiting him from taking more trips abroad.

Nevertheless, the growers at the 1887 conference in Riverside passed a resolution to petition their congressmen to persuade the federal government to send an entomologist to Australia. Norman J. Colman, U.S. Commissioner of Agriculture and Riley’s superior, sent a letter to Representative Felton from San Francisco’s Eighth District. He pointed out that although travel outside the United States was prohibited, the United States Government would be participating in an International Exposition in Melbourne next year. He wrote, “This exposition in many ways would further the investigation referred to in your memorial.”

Frank McCoppin, former mayor of the city of San Francisco, was soon appointed to head the Melbourne Exposition Commission. He immediately set aside $2,000 to pay the expenses of an entomologist to go with the U.S. delegation.

Riley had two field agents in California, Albert Koebele, a naturalized German immigrant stationed in Alameda, and Daniel Coquillet, who was in Los Angeles working on chemical controls for cottony cushion scale. Riley sent Koebele to Australia. In October 1888, Koebele reported from Australia that he had found large numbers of a cottony cushion scale parasite, Cryptochaetum iceryae. He sent about 12,000 specimens back to California to be released. Everyone involved with the project expected this member of the fly family would provide the best option for controlling the scale.

A Voracious Lady Bug

On October 15, 1888 in North Adelaide, Koebele found the vedalia beetle, a ladybug, feeding on cottony cushion scale. In 1889 in his National City address to the Fruit Growers Convention, Coquillet gave this report of Koebele’s observations: “…in certain places where he found these ladybugs, the orange growers did not fear the Icerya; they paid no attention to them. I judge from that the orange growers think it is not necessary, because the ladybugs and other insects that prey on them keep them within due limits.” Koebele, however, sent only 129 specimens to Coquillet in Los Angeles. Twenty-eight beetles arrived on November 30, 1888; 44 on December 29; and 57 on January 24, 1889.
By April 16, 1889 when he spoke to the convention in National City, Coquillet believed the vedalia beetle was going to be the best bet for controlling the scale. He said he had established colonies in the open air at Colonel J. R. Dobbin’s ranch and Mr. A. Scott Chapman’s ranch, both in the San Gabriel Valley.

Coquillet reported he placed the small red and black lady beetles under a tent over an infested orange on the J. W. Wolfskill Ranch in Los Angeles. The larvae of the ladybug destroyed at least a half dozen cottony cushion scale per day. The winged adult also fed on the scale. He estimated each vedalia beetle, larvae and adult, might destroy 250 scale insects.

He described the vedalia beetle to be “voracious” and he felt “…the successful introduction of this insect seems insured beyond a doubt.” When he placed that tent over an infested orange tree to breed the vedalia beetle, Coquillet created the first insectary in California.

By July 2, 1889, Colonel Dobbins announced, “The vedalia beetle had multiplied its numbers and spread so rapidly that every one of my 3,300 orchard trees is literally swarming with them. … People are coming here daily, and by placing infested branches upon the ground beneath my trees for two hours, can secure colonies of thousands of vedalia beetles which are there in countless numbers seeking food. Over 50,000 have been taken away to other orchards during the past week, and there are millions still remaining. … I feel positive from my own experience that the entire valley will be practically free from Icerya before the advent of the new year.”

Chapman had been ready to abandon his orchard in the San Gabriel Valley to the cottony cushion scale. On October 18, 1889, he was able to report the vedalia beetle had eradicated the scale from 150 acres of his land.

Quickly, the vedalia beetle spread throughout the state, suppressing the scale. The cost of bringing the parasite to California was about $1,500 and the savings to growers has been undoubtedly in the millions. Orange shipments exported from Los Angeles County in 1889 jumped from 700 carloads the previous year to 2000 carloads.

L. E. Caltagirone and R. L. Droutt wrote in the Annual Review of Entomology in 1989, “…no single achievement has more thoroughly, soundly, and significantly established a major pest control tactic than the vedalia project. All subsequent projects, programs, advances, and refinement in theory and practice of biological control have sprung from this single event.” Charles Valentine Riley is credited with being the originator of this tactic and is known today as the “Father of Biological Control.”

Other Sources:
“History of the Vedalia Beetle,” L. E. Caltagirone and R. L. Droutt; Proceedings of the Fruit Growers and Farmers Convention, Issue 9 and 11

Charles Valentine Riley
Father of Biological Control

Charles Valentine Riley, born in Chelsea, England, on September 19, 1843, moved to a farm in Illinois when he was 17. From there, he wrote for the Prairie Farmer about his
observations of insects that were damaging crops. At 21, he began working as a reporter, editor and illustrator for an entomological journal in Chicago.

His writings attracted the attention of Benjamin Walsh, Illinois state entomologist. In 1868, Walsh used his influence to secure Riley’s appointment to the newly created position of state entomologist for Missouri. During the 11years Riley held this position, he wrote nine annual reports on the entomological conditions of the State. The reports averaged 164 pages and described in detail the insects damaging crops, their life cycles and their predators and parasites. The reports, authorities agree, constitute the foundation for the study of modern entomology. He was decorated by the French government for his work to control grapevine phylloxera.

In 1878, Riley was appointed chief of the Entomological Service for the U.S. Department of Agriculture (USDA). In 1885, he donated his entire 115,000 specimen insect collection to the U.S. National Museum, now the Smithsonian. Riley became the Museum’s first curator of insects. During his career, he published more than 2,400 articles. He left the USDA in June 1894.

Riley died on September 14, 1895 at age 52. As he rode downhill on a bicycle near his home in Washington D. C., he hit a paving block that had dropped onto the road. He flew off the bike and fractured his skull. He never regained consciousness, and died at home the same day. He left a wife and six children. - John Blocker

© SAN DIEGO FLORAL ASSOCIATION and © John Blocker.
These stories may not be published in any form or copied onto another media without written permission from San Diego Floral Association.

Mission: To promote the knowledge and appreciation of horticulture and floriculture in the San Diego region.