LOS ANGELES -- Greg, a member of the Rollin 60's gang leaned on a cane behind the Seventh-day Adventist Church on Western Avenue at 70th Street and discussed the territory of the rival 8 Tray gang, whose boundary was just out of sight on the other side of the avenue.

"Crips and Crips fight more than Crips and Bloods," said Greg, 18, referring to the city's predominant black gangs. "All the Bloods get along. All the Crips don't, and I can't understand why . . . People just don't want to get along."

The Rollin 60's and 8 Tray gangs are part of the Crips, whose notoriety and that of the Bloods is widespread. The Crips wear blue, and the Bloods wear red. They shoot at each other, sometimes in "drive-by" incidents, and drug dealing by some of their members has spread to Seattle, Phoenix, Baltimore, St. Louis, Anchorage and other cit- ies.

But, the geography of gang life here is beginning to change dramatically as reality obscures myth. A little-known Hispanic gang known as 18th Street has become the largest gang in Los Angeles.

A map drawn from interviews with gang members, police and community experts shows remarkable growth by Hispanic gangs moving, as is the Hispanic population, from bases in East Los Angeles to traditionally black south-central Los Angeles.

The most recent statistics on gang-related crime also show a sudden decrease in south-central Los Angeles, while the depressing cycle of drugs and drive-by shootings continues elsewhere.

The effect of the Hispanic surge on drug dealing by black gangs remains unclear. Police and academic experts said only that, in Los Angeles gang life, nothing stays the same for long.

The Los Angeles County Sheriff's Department has identified 45,776 Hispanic gang members, far more than the 30,845 identified black gang members -- 22,594 Crips and 8,251 Bloods.

Of the 60 gang-related homicides this year, only 20 have been connected to black gangs, authorities said. "Black gangs have slowed down somewhat," said Lt. Charles Bradley of Operation Safe Streets in the sheriff's department.

While incidents of gang-related crimes -- including homicides, robberies, assaults, rapes and shootings -- dropped citywide by 5 percent in the first three months this year, they have plunged 26 percent in south-central Los Angeles. "There's been a lot of concentration in that area," Bradley said, referring to pressure from law enforcement and community-based organizations, marches against gang violence and imprisonment of gang members.

Crips and Bloods still rule south-central but must share turf with Hispanic gangs, which Greg calls "SA" gangs, for South Americans. "We have a Mexican gang in our neighborhood, the C14s," he said. Although C14s live in a section of Rollin 60's territory, they do not fight the black gang. Their rival is the 18th Street gang.

"There's very little mixing of the races," said Lt. Chuck Brantley, also of Operation Safe Streets. Gangs "almost exclusively fight against their own race."

In 1988, 18th Street had more than 2,000 members in a 12- to 13-block territory, according to Gene Mendosa, crisis-intervention worker for Community Youth Gang Services, a government-funded agency that focuses on reducing gang violence.

Now, 18th Street has more than 6,000 members, far more than any single gang in the Crips or Bloods coalitions, with offshoots spreading in several directions. "They've been seen everywhere in and out of the city," Mendosa said.

The second largest Hispanic gang, with only 500 members, is White Fence, which originated in the 1920s and is thought to be one of the first Hispanic gangs in Los Angeles, Mendosa said. The sheriff's department calls Hispanic gang members "the traditionals" because they were formed in the early 1920s as social clubs.

Most Hispanics "have lived in those neighborhoods for some time now," said Mendosa, who works in East Los Angeles. "They claim it."

Hispanic gangs are more territorial than black gangs. "Black gangs started for the profit motive -- ripping people off, drug sales or extortion," Brantley said. The Crips date to the early 1970s, with the Bloods forming a number of years later.

Greg, who declined to give his last name or street name, has been one of approximately 300 members of the Rollin 60's, the third largest Crips gang, since 1984. All his group wants, he said, "is to sit back, sell cocaine and make money, but then somebody from a different neighborhood has to come over here and shoot at us. That's what starts it {the violence} all back up again."

After a large number of Bloods bordering Rollin 60's territory had been sent to jail or killed, Greg's gang moved in. "What they do is move a block or two over," out of their territory, he said, "and sell cocaine in the Bloods' neighborhood. Therefore, it cuts the Bloods off at a certain point," expanding Rollin 60's territory.

Gerry Riposa, professor of political science at California State University in Long Beach, said, "The idea of territory has to be integrated into economics, and not just neighborhood." Black gangs traditionally deal in the drug trade, but Hispanic gangs seem to be moving in the same direction. "Economics are a function of recruitment," Riposa said.

In a city where a gang's size determines its power, recruitment is the future, "which is why they lean so heavily on the 12- and 13-year-olds," he said.

"Power rises and falls, according to their ability to recruit and to maintain their presence on the street," Riposa said. "When younger recruits see a gang is powerful, they join."

Bradley said Los Angeles County had 400 gangs in 1984 and 754 last year, with graffiti as the identifying source. "Graffiti is the newspaper of the streets," said Judy Herrera, supervisor of the graffiti-removal unit for Community Youth Gang Services. Gangs, she said, "tell a story" with graffiti, so law enforcement, people in the community and gang members read the walls to determine activity in the area.

Graffiti reveal names of new and deceased members -- "RIP CHAKA" is a typical death notice -- and sometimes whether attacks by rival gangs can be expected. Graffiti identify territory, whether another gang is trying to infringe on it and how far into a gang's territory one has ventured.

Manuel Velasquez, a team leader on a crisis-intervention unit for Community Youth Gang Services in the San Fernando Valley, has seen an influx of gang members from south-central and east Los Angeles into the northwestern suburban area.

Velasquez has identified 28 relocated street gangs, including Rollin 60's and 18th Street. The members' families move to the valley to get away from the gang problem. Then other gang members visit or new members are recruited, and a new gang is formed. It often keeps the parent gang's name or, like offshoots of 18th Street, adds westside and northside to their name.

"A lot of people don't take valley gangs serious," Velasquez said. "They should know that there's no way you're going to get them out once they're settled, and you'll have another south-central in the valley."