Mosquitoes ticks and jellyfish will converge on Maryland this summer in what may be one of the worst infestations in recent years, state officials said Thursday.

Experts say you can blame it on the rains.

"We're having some rather severe mosquito problems as a result of the rain we've had in the last six weeks," particularly on the Eastern Shore of Chesapeake Bay, said Stanley Joseph, acting chief of the state's mosquito control division.

The Eastern Shore mosquito problem was at its worst in 1977 and 1978. "We expect this year to be a little better," Joseph said - but that forecast could grow bleak if rainy weather continues supplying the water needed for massive hatching grounds.

State entomologist Cyrus Lasser said the heavy rains have made it difficult to control the mosquito population - particularly in the marshes of Dorchester and Somerset counties - but large problems so far have been averted.

"We would have had major problems . . . without the spraying, but the salt marsh mosquito problem so far has been very low," Lasser said.

Mosquito control chief Joseph said the state would spray the Eastern Shore area again before the end of the month to curb the salt marsh mosquito population. But fresh water mosquitoes are more abundant than last year, according to Lasser.

In addition to mosquitoes, Maryland residents face an increased number of ticks and jellyfish this summer.

State veterinarian Kenneth L. Crawford said the rainy weather has produced more grassy areas for small rodents, whose higher survival rate fosters an increasd food source for ticks.

A greater number of ticks may lead to more cases of Rocky Mountain Spotted Fever, which ticks carry.

In Maryland, 124 persons contracted the fever last year; three persons died, Crawford said. Though only 27 cases of Rocky Mountain Spotted Fever have been reported so far this year, the figure may soar by the end of the summer, he said. "We're just getting into it."

The pest problem around the Chesapeake Bay will probably be worsened by the painful pests thriving within the water - jellyfish, or nettles.

University of Maryland researcher David Cargo said the jellyfish - filmy white, umbrella-shaped creatures with 32 tenacles to three feet long - will dot the bay earlier and in the highest numbers since 1970.

"It isn't going to be a super-infestation like in the late '60s (but) they'll become a real nuisance," he said.

Sea nettles, which thrive in Chesapeake Bay because of its salt content and oyster-lined bottom, usually reach peak numbers in August and die by Thanksgiving - but they will begin appearing in large numbers within 10 days.

Each of the jellyfish tenacles is coated with hundreds of thousands of microscopic stinging cells. The poison-coated, threadlike cells penetrate a swimmer's skin and leave a sharp burning feeling for several hours, Cargo said.