What is causing the decline in monarch butterflies?

The loss of milkweed in agricultural fields is a major cause of decline in monarchs, though there are other factors contributing to the decline in milkweed availability. Urban sprawl and continuing industrial development are also major factors influencing the decline in quality monarch habitat.Click to see full answer. In this regard, what factors cause decline in monarch butterflies?“There are three main reasons for the decline,” says Tremeer. “The use of genetically modified, herbicide-resistant crops that destroy milkweed and nectaring habitat, the deforestation in Mexico, and the recent bouts of severe weather.” The biggest threat throughout North America is habitat loss.Also Know, what is killing monarch butterflies? Humans, with all our farm fields, roads and buildings, are largely to blame for the monarch’s decline. Deforestation has decimated the monarch’s preferred habitats both north and south. And herbicide-resistant crops allow farmers to spray stronger weedkillers on their fields, which kills native milkweed in the process. Just so, why are butterflies decreasing? Droughts, pesticides and loss of habitat are seen as reasons for the Western monarch’s decline. Pesticides, habitat losses and more frequent and severe droughts caused by climate change are believed to be the primary reasons for the decimation of the butterfly population, Xerces says.Are butterflies declining?Intensive long-term monitoring of individual butterfly species has provided rigorous, quantitative estimates of declines. Most prominently, the Eastern North American Monarch has declined by over 85% [16] and the Western North American Monarch by over 95% [17] over the past two decades.