WEST BRANCH, Iowa (KCRG-TV9) Over the last decade, Iowa has noticed a major decline in the monarch population as well as other pollinators, in fact, the whole Midwest has seen this decline.
A group of Cornell College students is looking into what's causing those numbers to go down.
They have been researching monarch butterflies in different areas, including the Hoover National Historic Site in West Branch.
Experts at Cornell College say originally conservation scientist thought they were seeing fewer monarchs in Iowa was because there was less milkweed in the area.
That's the only plant butterflies will lay their eggs on and caterpillars will eat, but now they're saying that might not be the case.
Over the summer, students at the Cornell Summer Research Institution recorded the number of monarch eggs and caterpillars they found on milkweed.
They noticed there isn't a lot of butterflies using these milkweed plants and that’s why they think other factors are causing the population to go down.
In North America, much of the prairie land has been destroyed.
“Iowa used to be covered by prairies and now we know there's less than one tenth of one percent left of our native prairie, we have all these restored prairies but even restored prairies have environmental toxins kind of creeping in and human disturbances,” says Tammy Mildenstein, assistant professor of biology at Cornell College.
Some of those toxins are pesticides commonly used on farms.
The conservation scientist also says a cold front in Mexico may have something to do with wiping out a lot of the monarch butterflies last year as well as the destruction of monarch habitats in Mexico where these butterflies migrate in the winter months.
Students say having monarch butterflies benefits everyone.
"They're making all the flowers able to go to seed so they can come back the next year and without monarchs and pollinators species like that there wouldn't be flowers, there wouldn't be most of our food in our grocery stores,” says Marin Dettweiler, a student with the Cornell Summer Research Institution
This is the third summer students have been outside doing this study.
Next month these students will still work on their research, but instead of being out in the fields, they'll be recording all their data.
Some of the ways people can help try and build up the monarch population are by planting some of the native prairie grass and milkweed to Iowa.