Scientists Seek Public Help to Track Monarch Butterfly Milkweed Habitat

Tom Harvey, 512-389-4453,

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“Where have all the monarchs gone?” This is becoming an oft repeated query, and Texas Parks and Wildlife Department biologists are asking for citizen help in answering the question.

Since monitoring of overwintering monarch butterfly (Danaus plexippus) populations in the Mexican states of Michoacán and México began in 1993, the World Wildlife Fund has documented a significant decline in overwintering area (a surrogate for population size) that reached an all-time low in the winter of 2013. Monarch decline has been attributed to multiple factors including illegal logging of Oyamel forests in Mexico, extreme weather conditions in overwintering and breeding grounds, and widespread decline in milkweed abundance in the United States.

Biologists from the department’s Wildlife Diversity Program recently launched a project to explore Texas milkweed and determine where it is, how much is out there and are the monarchs using it. The project developed as a result of concerns arising from the Midwestern U.S. that herbicide-resistant crops are resulting in increased use of herbicide to control weeds and a resulting loss of milkweed in that region. Loss of milkweed is significant since it is the only plant monarch caterpillars can eat.

This project is housed on the internet app, a platform being used by researchers worldwide who look for citizen assistance in supporting their work. To participate, a volunteer should first join the project after creating a free account on iNaturalist. When people then see milkweed in their travels, they can snap a picture, add it to the project, and answer the four brief questions about your observation. They do not even have to know any of the 40-some species of milkweed found in Texas – they can simply say “milkweed” and ask for assistance in identifying the plant.

Through this project, the Wildlife Diversity Program hopes to produce a map showing where milkweed is found in Texas, what species of milkweed people are finding, whether it is natural or cultivated, and whether monarchs are using it. Patterns in agricultural areas will be interesting, but urban communities are a concern too.

“People tend to want to remove “weeds” from their gardens, often by using an herbicide,” says Mark Klym of TPWD, one of those involved in the project. “If we are using this in our gardens anywhere close to where milkweed is growing, the wind could carry the product to the plant and the plant could be lost.”

See the Texas Milkweeds and Monarchs project web page on to learn more.