LAS CRUCES, N.M. —  Countless caterpillars have invaded the rural areas around Las Cruces, crawling into homes, drowning in swimming pools and getting squished on roads.

New Mexico State University entomologist David Richman said such invasions of the harmless caterpillars are not predictable.

"The weather has to be just right. ... This is a boom-and-bust insect," he said. "They happen and you may not see them again for another 20, 30 years."

The last an infestation of this level in the area was 15 to 20 years ago, Richman said.

The white-lined sphinx moth caterpillars are especially prevalent in the Talavera area and along U.S. 70 on both sides of the Organ Mountains.

"I've literally pulled about 500 of them from the swimming pool," said Talavera resident Rick Nelson.

"I know they're harmless but they're creepy," said another Talavera-area resident, Jennie Meehan. "They're just creepy and the whole road was yellow with them."

Recent rains created an abundance of food for the caterpillars, which feed primarily on gaura and evening primrose, Richman said. Dry weather earlier in the year also meant fewer insects such as wasps, which prey on the caterpillar.

The insects will only be at the caterpillar stage for another week or so, and the white-lined sphinx moth has value, said Jackye Meinecke, who owns a Las Cruces garden store.

"It's a pollinator for a lot of our night-blooming plants, including Organ Mountain primrose, one of those endangered plants," she said. "They're an important part of our environment."