Montgomery County State's Attorney Andrew L. Sonner yesterday "declared war on burglars" in an effort to reverse a burglary rate that has risen 44 percent over the last two years in Maryland's wealthiest county.

Sonner announced plans to form a seven-member team of assistant states' attorneys that will handle all burglary cases as well as all drug and juvenile court cases. Sonner, a persistent critic of lenient sentences by county judges, also said his office would routinely ask judges to give jail time in all convictions, even for first offenders, and would curtail the number of cases that are resolved by plea bargaining.

"The word on the street is that if you break into a house in Montgomery County you get probation," Sonner said. "We want the word to be if you break into a house in Montgomery you go to jail. We want burglars to hear what the slammer sounds like and to know what it's like inside a jail."

He said one of the ways his office planned to drive home the get tough position was by printing up a batch of bumperstickers that say "Break Into a House, Go to Jail."

Sonner made his announcement at a press conference in the county office building in Rockville with Montgomery executive Charles W. Gilchrist, Police Chief Bernard D. Crooke and Department of Corrections director Gary R. Blake.

Gilchrist said he would request $39,000 for three new positons in the state's attorney's office.

It was a rare joint appearance by Sonner and Gilchrist, two Democrats whose relationship has been less than amicable since the election in 1978 when Gilchrist declined to endorse the state's attorney.

According to Sonner's figures, there were more than 8,000 burglaries in Montgomery last year, costing county residents more than $5 million. Residential burglary rates for the first quarter of 1981 climbed more than 8 percent, a rise that followed the dramatic 36 percent upsurge last year which prompted the county police department to reorganize and Gilchrist to add more officers.

Most alarming to the officials was mushrooming juvenile crime by local youths. Just under half of the 934 people arrested for burglary by county police last year were juveniles and 90 percent of them lived in the county. More than 76 percent of all people arrested for burglary are 21 years old or younger.

Sonner began to study the way these arrests were disposed after the 1980 statistics were announced in February. He looked at the last 100 burglary cases entered in 1980 and found that 74 percent of the juvenile burglars were repeat offenders who had been arrested an average of six times. Jail terms were meted out in only 4 percent of the cases.

In Circuit Court, 44 percent of the people convicted for burglary got suspended sentences. Only in 18 percent of the cases were jail terms longer than two years.