Milkweed plants -- the only kind that the butterflies feed on to survive -- are not in plentiful supply, he said.
"The conditions have been dry both here and in Mexico in recent years. It takes four generations of the insects to make it all of the way up to Canada, and because of lack of milkweed along the way, a lot of them just don't make it."
Reports coming from Mexico where the Monarchs have their breeding grounds show their numbers are significantly down, a disturbing trend lasting much of the past decade, a university release said Wednesday.
Wildfires in the past few years have hampered milkweed growth, researchers said, and even though there are more than 30 types of milkweed in the state there isn't enough to sustain the Monarchs as they start their 2,000-mile migration trip to Canada.
"It is important to have a national priority of planting milkweed to assure there will be Monarchs in the future," Wilson said. "If we could get several states to collaborate, we might be able to provide a 'feeding' corridor right up to Canada for the Monarchs."