The Butterfly Pavilion just opened this week at the Natural History Museum of Los Angeles County, and it already started to draw crowds.

When people picture a classic butterfly, most probably think of a Monarch with a bold orange and black pattern, but they're often confused with Painted Ladies that share a similar pattern. With all the recent rain and weeds, they have been swarming the county. 

"It’s really nice to see a wildlife spectacle here in the city," said Brian Brown, curator of entomology at the Natural History Museum.

"Entomology is a field in which you can never run out of new things to discover. It’s like being Darwin everyday," he said.

In other words, he studies insects.

"Monarchs have a very restricted food source. It’s just milkweeds and they also, at least the Eastern Monarch population, [have] a very restricted area where it over-winters," Brown said.

Unfortunately, the latest numbers from the Xerces Society, which promotes invertebrate conservation, show only around 28,000 monarchs were wintering along the California coast. That’s down 85 percent from the previous year, but exhibits like the butterfly pavilion increase awareness and education.

"It’s a good way to discuss what’s going on in the world and what’s going on with the climate because the butterflies are responding to climate and different factors," said Crystal Oswald, who's a live animal keeper at the museum.

Nobody knows for sure what’s causing some butterflies in California to disappear, but scientists say the use of pesticides, fewer open spaces, and climate change can all affect migration patterns and food sources.

"We have monarchs that come to our lemon tree," said Nick Terry, who was visiting from Pasadena with his two young girls. They were using the butterfly guide to help identify what they were seeing. 

"They are different colors and they look pretty," said his daughter, London Terry.

"Some of them will use their colors to warn predators, 'Hey, I’m toxic," Oswald said.

As for the monarchs, Brown said if you want to see more of them, "stick with the native milkweeds."

But to learn about different kinds of butterflies, a stroll through the pavilion could lead to all sorts of discoveries.

"You can see more here than you can by just walking outside," Brown said.