The annual migration of the Monarch Butterflies is, as you will now if you have been following WOTM over the last few months, an amazing feat of endurance. They over-winter in the forests of Mexico and migrate up to the northern border of the United States and amazingly, it's a relay-race because the first generation of butterflies that leave Mexico only make it half the way. At this point they breed and it's the second generation of butterflies that complete the journey to northern US and Canada.
So great is the urge to reproduce that the exhausted female butterflies have been seen dragging themselves from plant to plant as they use the last of their energy to lay.
As the generations of caterpillars pupate and emerge as butterflies, each new brood moves northwards, rolling out the range of the Monarch across the USA. Karen Oberhauser from the University of Minnesota co-ordinates a public survey of the Monarch eggs and the impressive black, white and yellow striped caterpillars as fat as your finger which chomp all day on milkweed plants.
But the milkweeds have a problem and so do the butterflies. WOTM caught up with Karen a few days ago to find out what this year’s survey is showing.