The Xerces Society count along the California coast shows about 2,000 monarchs. It says that's down about 80 per cent in the last two decades.
Andalyne Tofflemire is the Director of the Cambridge Butterfly Conservatory, which is home to over 2,000 butterflies and moths.
She says people are caring more, and yet the numbers of monarchs keep going down instead of going up, or stabilizing.
She says it's a lot lower.
Tofflemire tells 570 NEWS that it can be hard to estimate the number of butterflies individually.
She says, "they add it up as a number of hectares that they are taking up in overwintering sites."
She says, "that's about two hectares which is not a whole lot of space. I mean, 20 years ago, it used to be almost 20 hectares."
Tofflemire says just planting some milkweed in the corner of your yard can help them.
The Butterfly Conservatory offers a monarch education program on its website.