MILWAUKEE, SEPT. 1 -- The plagues that beset the Baltimore Orioles tonight were not of Biblical proportions, but they were about the best duplication baseball can offer. A night that began with insects engulfing County Stadium turned upon Baltimore shortstop Cal Ripken's first throwing error in almost a year and ended with a 4-3 loss to the Milwaukee Brewers.

The evening's announced attendance of 18,601 didn't include the bugs that made life on the field an Alfred Hitchcock-like nightmare through the early going and threatened to produce the Brewers' second pest delay in a week.

"You shouldn't have to play under these conditions," Orioles Manager Frank Robinson said. "When your concentration is affected, you shouldn't have to do it."

The insects eventually subsided, but matters only got worse for the Orioles. Ripken's off-target throw on Greg Vaughn's fifth-inning ground ball led to two unearned runs on Robin Yount's two-out single. That helped make a loser of rookie starter Ben McDonald (5-4), who also yielded Paul Molitor's seventh-inning home run that gave Milwaukee a 4-1 lead.

Baltimore got within a run on pinch hitter Sam Horn's two-run single in the eighth but left two runners aboard later in the inning against reliever Chuck Crim. The Orioles got a homer from Ron Kittle and had nine hits off starter Ted Higuera but proved wasteful once more.

The loss was the Orioles' 18th in 25 games and dropped them a season-high 11 games below .500. They fell to their low-water point of 14 1/2 games behind the Boston Red Sox in the AL East. Milwaukee won for the 13th time in 17 games.

Higuera entered tonight's game with an 8-6 record and a 3.19 ERA but is enduring a trying season. He has had a bruised knee, a pulled groin and a sore shoulder and his mother died.

And his past two outings each have been entomologists' specials. He was pitching Monday in the Skydome when gnats delayed the game half an hour; that problem was easily solved, for Blue Jays officials simply closed the retractable roof and cranked up the air conditioning until the pests were dispersed.

There were no such solutions tonight, however, when mosquitoes and assorted other insects descended in the first inning. Players and coaches doused themselves with bug repellent, and ushers tried to accommodate the fans by walking up and down the aisles with spray cans in hand.

Clouds of insects were visible around the light towers, and the umpires seemed to consider stopping play. Spectators flocked to the exits, but diehards stayed put and the contest continued.

The Orioles seemed divided as to whether the bugs primarily were gnats or termites. "Whatever they were, they don't taste too good," said McDonald, who got a mouthful of them in the first inning. "I was right at home with those bugs. They wanted to stop the game, but I wanted to play."

He had lost his previous three starts after a five-victories-in-five-outings beginning. In the defeats, he had struggled to control his curveball, used his change-up only sparingly and yielded his first five home runs of the season.

He appeared in better form in the early going tonight, although he fell behind, 1-0, in the second. Dave Parker led off with a single and stole second when catcher Bob Melvin twisted an ankle and couldn't throw.

B.J. Surhoff moved Parker to third with a grounder, and Rob Deer scored him with a bouncer that Ripken seemed to field in time to get Parker at home; but he threw to first instead.

"We got kind of lucky tonight," Parker said. "A guy like Ripken doesn't give you too many things. I thought he'd come home. He had me. Maybe Cal doesn't like bugs."

The Orioles evened matters at 1 on Kittle's homer leading off the fourth. It went into the left field bleachers, his 18th this season and second in six days.

Both teams squandered middle-inning opportunities. The Orioles followed Kittle's homer by wasting a first-and-third, one-out chance, and the Brewers did the same in their half.

Then the Orioles failed to capitalize on Mike Devereaux's leadoff double in the fifth. Joe Orsulak bunted Devereaux to third, but Ripken grounded out with the infield in and Kittle lined to center.

Ripken's first throwing error since Sept. 24, 1989 began the home fifth. He fielded the ball cleanly and set himself, but sent his in-time toss up the right field line to pull Mickey Tettleton off the bag. It was his third error this season, all on the road, and first since July 28, when his major-league-record 95-game errorless streak ended.

"You don't see that very often because he's had such an outstanding defensive year," Robinson said.

Bill Spiers's sacrifice attempt forced Vaughn at second, but McDonald walked Molitor one out later. After Jim Gantner's flyout, Yount lined a single up the middle for two unearned runs.

Orioles Notes:

Four players were added to the roster today. Pitcher Bob Milacki was activated from the disabled list, left-hander Kevin Hickey and utility man Jeff McKnight reported from Class AAA Rochester and waiver claim Brian DuBois joined the team.

BALTIMORE ab r h bi MILWAUKEE ab r h bi Devereaux cf 5 0 2 0 Molitor 3b 3 2 1 1 Orsulak lf 2 0 0 0 Gantner 2b 4 0 0 0 Gallagher ph 0 0 0 0 Yount cf 4 0 1 2 C.Ripken ss 5 0 0 0 D.Parker dh 3 1 1 0 Kittle dh 5 1 2 1 Surhoff c 4 0 1 0 Tettleton 1b 4 1 1 0 Deer rf 4 0 0 1 Hulett 2b 4 0 0 0 Brock 1b 2 0 0 0 Worthingtn 3b 4 1 2 0 Vaughn lf 3 0 0 0 Melvin c 3 0 1 0 Felder lf 0 0 0 0 Horn ph 1 0 1 2 Spiers ss 3 1 1 0 McKnight 1b 0 0 0 0 S.Finley rf 4 0 2 0 Totals 37 3 11 3 Totals 30 4 5 4 Baltimore 000 100 020 3 Milwaukee 010 020 10x 4

E: Worthington, Molitor, C.Ripken. DP: Milwaukee 1. LOB: Baltimore 10, Milwaukee 5. 2B: Devereaux, Worthing

Umpires: Home, Morrison; First, Joyce; Second, Barnett; Third, Kosc.

T: 2:40. A: 18,601.