Monarch butterflies are incredibly unique!
Instead of overwintering in Pennsylvania like every other insect, Monarchs MIGRATE back to Pennsylvania every summer.
Yes, you read that right. Monarchs act more like birds! Every fall, they migrate south to Mexico, and then each summer, these butterflies come back north to Pennsylvania to reproduce and lay eggs.
So when exactly can you expect Monarchs to arrive in Pennsylvania?
As you can imagine, there is not an exact day that all the Monarchs get together and decide to start migrating back to Pennsylvania. Each year, the actual time changes depending on the temperature and availability of nectar sources. It also matters where you live in Pennsylvania, as the southern areas will see Monarchs slightly before the northern parts.
But with that being said;
Most Monarchs get to Pennsylvania in mid to late June.
And just so you know, the butterflies that first arrive are NOT the same insects that left the previous fall. The first Monarchs you see each summer are the GRANDCHILDREN of the individuals that left last year.
*On a side note, the migration of Monarchs is incredibly fascinating. It takes four generations of butterflies to make the complete annual journey. All the details are outside the scope of this article, but I encourage you to educate yourself because it will blow your mind!
Anyways, once the Monarchs get to Pennsylvania, they immediately start laying eggs to produce the next generations. These individuals will eventually be the butterflies that fly back to Mexico.
Luckily, we can all help Monarchs!
Making sure your yard is FULL of native plants is one of the best things you can do. Try to pick flowers with different bloom times, so you always have fresh blossoms full of nectar from when they first arrive in June to when they leave in the fall.
In addition, try reading this article, which is full of tips that will make your yard more friendly to butterflies, including Monarchs:
When do you usually see the FIRST Monarchs in Pennsylvania?