A cool spring has kept this year's crop of ladybugs from hatching, which in turn has allowed the voracious aphid to multiply unfettered, seriously damaging crops, a farm expert said Tuesday.

Aphids have destroyed up to 30 percent of the region's first cut of alfalfa, and the green pests have also damaged fruit crops and pistachio trees, said Utah State University extension agent Adrian Hinton.The cool spring has also delayed the hatching of the lacy wing and the praying mantis, allowing the aphids to grow exponentially, Hinton said.

Washington County farmers should resort to herbicides to protect their produce, Hinton said, adding that because the aphid is at first too small to see - and by the time it gets large enough, the damage has already been done.

Spraying of about 1,200 acres of alfalfa has lessened damages, but about 35 percent of the first cutting has been eaten, the agent said.

"We normally have warm weather by now, but it has stayed below the 80 degrees needed for ladybugs to hatch," Hinton said.

Pecan crops have been damaged as well, Hinton said, and so have peach orchards.

The tiny green bug sucks the juices from the leaves and stems of green plants, preventing nutrients from reaching the fruits, Hinton said.

The result is that damaged fruit will be stunted, and pecans and pistachios will be shriveled and not as marketable.

Unless controlled, aphids will continue to hatch, producing five generations in one growing season, Hinton said.