While serious crimes reported to police in Northern Virginia in 1977 fell, serious offenses committed by juveniles in the region increased, according to a report under review by the federal government.

The study, compiles by local prosecutors, police and citizens for the Northern Virginia Planning District Commission, said juveniles accounted for one in four drug arrests last year.

Of the 8,024 arrests in 1977 for serious crimes - murder, rape, robbery, aggravated assault, burglary, larceny and auto theft - 41.2 percent were juveniles, up from 36.7 percent in 1976, the reports said.

Juveniles also made up most of the arrests for property crimes: 60.9 percent of those held for burglary and 53.3 percent for auto theft. Larcenies were reported as 34.8 percent.

In addition to statistics on juvenile, the study found a rate of apprehension for all criminals in Northern Virginia 4 percent below the national average and cited frustration among victims and witnesses with the criminal justice system.

The report, used by the Law Enforcement Assistance Administration to determine the extent of federal funding for regional justice projects, was distributed to Northern Virginia officials yesterday.

Although he said he had not had time to read the lengthy report, Arlington Police Chief William K. (Smokey) Stover said that juvenile burglars are a particular problem. "I believe that's the picture throughout the state of Virginia."

The solution at the (juvenile crime) problem is the $64 question," said Fairfax Commonwealth's Attorney Robert F. Horan Jr., who earlier yesterday was in court with a celebrated Northern Virginia juvenile case, the death of 12-year-old Billy Viscidi in suburban Vienna.

Juvenile criminals "don't fit the pattern - the deprived kid, a ghetto family and all the theories of a difficult life," Horan said. "These kids are coming from fine homes."

Northern Virginia jurisdictions covered by the report included Fairfax, Arlington, Prince William and Loudoun counties, and the cities of Falls Church, Fairfax, Alexandria, Vienna, Herndon, Manassas, Manassas Park and Leesburg.

Although the region's police were below the national avarage for closing cases by arrest, the report said, they bettereed the national average for arrest in cases involving burglary, robbery and auto thefts.

Falls Church and Loudoun County experienced the highest rates of decrease in reported serious crime since 1975 with 33.4 percent and 21.6 percent, respectivey.

Reported serious crime increased by 1.1 percent in Herndon, 11.5 percent in Leesburg, 18.3 percent in Manassas, 50.8 percent in Manassas Park and 12.7 percent in Vienna, the report said.

Reported serious crime increased by 8.4 percent in Arington, 15.3 percent in Fairfax City, 4.2 percent in Fairfax County, 6.9 percent in Aexandria and 7.3 percent in Prince William County.

In murders, Northern Virginia police made arrests in 73.8 percent of the reported cases compared to 80.8 percent in other suburbs across the nation. They lagged behind other jurisdictions by 2.4 percent in rape cases, 52.8 to 50.4.

Horan noted that burglary was a difficult crime to solve because it usually involved few withness.

Bill Wood, a spokesman for Virginia's Division of Justice and Crime Prevention, said yesterday that the report is given "a considerable amount of weight."