There's been a big drop in the monarch butterfly population. By some estimates, they've declined by more than 90-percent over the past twenty years. Scientists say you can help monarchs by planting milkweed in your garden. It's the only thing the caterpillars eat. But if you're not careful, you could accidentally poison the insects you're trying to help.
In the second of our two part series from WYEP in Pittsburgh, the Allegheny Front's Rebecca Williams has more.
For the past couple of summers, Mariana Alva-Weis has been collecting monarch eggs and caterpillars and raising them in her backyard. She likes to watch them turn into butterflies.
"I think monarchs are very beautiful throughout their whole life and then they do that amazing thing, like some of them go across the world!"
But last year, she brought a milkweed plant home for some caterpillars to eat, and all three of the caterpillars died.
"It was sad! I was crying."
She isn't sure why that happened. Caterpillars can die for a lot of reasons - they can get diseases and parasites.
But you can also poison them without meaning to.
"It doesn't take much: two or three bites and they're dead."
Chip Taylor is the director of Monarch Watch at the University of Kansas. He says milkweed plants that are treated with insecticides called neonicitinoids can kill caterpillars. He says the insecticides are systemic - meaning they affect every part of plant. Taylor says when caterpillars eat treated leaves, the insects fall off the plant within minutes, curl up into a C shape and slowly die.
"We get emails very frequently, and we have to warn people don't buy milkweeds from big box stores unless you're certain they haven't been treated with neonics and very few of the big box stores can assure that."
Some of the big box stores are slowly making changes.
Starting this year, Home Depot is requiring its suppliers to label all plants treated with neonicitinoids. Last month, Lowe's announced they will phase out products containing the insecticides by 2019.
Neither company provided anyone for an interview.
In emails, both companies said they're working with suppliers to come up with substitutes for neonicitinoids.
Walmart also declined our interview request.
Chip Taylor with Monarch Watch says when you're buying milkweed you should ask if the plants are treated with systemic insecticides.
"Go to a native plant nursery and quiz the manager of the nursery about the use of systemics. If they can assure you they don't use any systemics, then buy the plants from them."
(transplanting sound - crinkly plastic)
"So we call this the big house and this is where the transplanting starts."
Bill Schneider owns Wildtype Nursery in Michigan.
"Over here are some of the milkweeds we transplanted in the last couple days; we can walk over and take a look."
He says they're not an organic nursery, but they don't use neonicitinoids.
"We are in a sense trying to grow insect food so we don't want the plants we produce to be toxic to insects."
Schneider says in our region there are a lot of native milkweeds to choose from. There's the showy butterfly weed with its orange or yellow flowers… swamp milkweed…. and common milkweed.
He says you can also go out and collect your own milkweed seeds from the wild.
"We go out seed collecting like some people go out garage sale shopping. You don't know sometimes what you're going to find but when you come upon it, it's exciting."
Schneider says it's a good idea to do that seed collecting away from farm fields and other areas that could be sprayed with pesticides.
To learn more about the Allegheny Front and efforts to save the Monarch butterfly, click here.