A helicopter sprays the pesticide malathion on a Newhall Land and Farming Co. agricultural field in a section of Valencia where Newhall Ranch Road would later be constructed.

Unfortunately no date accompanies this photograph, but based on what we know of this particular photo collection, it's probably late 1989 or early 1990.

Medflies — Ceratitis capitata, the Mediterranean fruit fly — had been a problem in California on and off since Gov. Jerry Brown's first term in 1975. Brown's name had become synonymous with medflies by Nov. 24, 1980, when the U.S. Department of Agriculture deemed his cautious approach to what had started out as an isolated problem ineffective. When Brown finally ordered the use of malathion eight months later on July 10, 1981, the infestation was so widespread that it necessitated spraying in populated areas, where residents were warned to stay indoors and cover their cars lest the chemical ruin the paint job. Brown's slow response undoubtedly cost him votes among Central Valley farmers the next year when he sought a U.S. Senate seat. He lost to San Diego Mayor Pete Wilson.

A sudden, major outbreak occurred in a dozen different locations beginning in July 1989. This time it was linked to an environmental terrorist group calling itself The Breeders. The group claimed responsibilty in December 1989 and threatened to release more medflies until the state stopped using malathion, which it did in March 1990, ostensibly because it wasn't working. Instead, the state started releasing sterilized medflies into the population, and they were unable to reproduce in sustainable numbers.

Medflies have been found in California since that time, but not in significant numbers. As of 2015, it is considered eradicated in California.

About the photographer: Photojournalist Gary Thornhill chronicled the history of the Santa Clarita Valley as it unfolded in the 1970s, '80s and '90s. From car races in Saugus to fatal car wrecks in Valencia; from topless beauty contests in Canyon Country to fires and floods in the various canyons; from city formation in 1987 to the Northridge earthquake in 1994 — Thornhill's photographs were published in The Los Angeles Times, The Newhall Signal, The Santa Clarita Valley Citizen newspaper, California Highway Patrolman magazine and elsewhere. He penned the occasional breaking news story for Signal and Citizen editors Scott and Ruth Newhall under the pseudonym of Victor Valencia, and he was the Santa Clarita Valley Sheriff Station's very first volunteer — and only the second in the entire LASD. Thornhill retained the rights to the images he created; in 2012, he donated his SCV photographs to two nonprofit organizations — SCVTV and the Santa Clarita Valley Historical Society — so that his work might continue to educate and inform the public.