Seeing yellow? Caterpillar migration swarms Phoenix-area neighborhoods

Thousands of fuzzy yellow caterpillars are creeping across the Phoenix metropolitan area, crossing roads, falling into pools and getting into homes.

Some may think they're cute or creepy, but they aren't dangerous, and they don't stick around for long. They make their way off the mountains like South Mountain and into the valleys.

"The whole mountain looks like it’s undulated with yellow as they’re coming down and coming really fast," said Ahwatukee resident Kelly Athena.

Athena has been studying these caterpillars in her Ahwatukee neighborhood for years. Not only observing them, but rescuing them from harm's way too.

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"So they usually come in Ahwatukee across Chandler Boulevard," Athena said. "I went over to 17th Ave where they usually are, and there were hundreds of them coming from the north and they’re heading towards the south.

"They’re heading for softer soil where they can dig their burrow and become a moth, so I took a bucket and filled it with about a hundred of them and then I got across the road and let them go in some of the spiderling and other bushes they like," she continued.

These furry yellow caterpillars will eventually turn into the white-lined sphinx moth.

Experts with Butterfly Wonderland say that they come off the mountains every August and hibernate before the monsoon season ends.

But unlike butterflies that create a cocoon, they bury themselves into the ground, turning into a pupa before transforming.

"Give a little bit of patience and kindness for these caterpillars, they’re not looking to hang around for long," said Derek Kellogg with Butterfly Wonderland. "They’re really looking to move right through our areas and get on to their next stage in life."

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Kelly Athena says these caterpillars are relatively harmless. They won't chew through clothes or food, but love Arizona's natural desert vegetation. But back in the day, they were an edible delicacy.

"Thomas Hunter, who was the first man to bring cattle to Arizona in 1868, he came over the ridge, and he looked down, and he saw about 250 Pima women in a line," Athena said. "They were out gathering mesquite beans and putting them in their baskets and around their necks they had beautiful necklaces. 

"As he got closer he saw that they were wriggling caterpillars, and they’d eat some raw, and they were taking some back to be roasted," Athena continued.

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For residents seeing an influx of the critters, it's not necessary to call an exterminator. They will be gone in a few days, so just be patient.

If you find them in a pool, use a little net and scoop them out, or use latex gloves to move them along so that they don't leave a yellow mark behind on you.