Nature Notes: Swallowtail Caterpillars

Black Swallowtails are common in our garden from spring to late fall. Several times during the season we find caterpillars munching on parsley or fennel which we plant specifically for them.

As soon as we see butterflies fluttering around the garden we start checking the host plants. In late March we found two early instar caterpillars on the bronze fennel.

March 30th

My children love to watch them grow and check on them daily. They molt often and grow quickly (the caterpillars not the children...although the children do grow like weeds).

April 5th

April 11th
These two caterpillars have eaten one entire plant, stems and all. One caterpillar has already gone to pupate. The second caterpillar has moved to the neighboring fennel plant and is still munching away.

Swallowtails tend to wander pretty far from their host plants to pupate. Before they depart they will empty their digestive track. If you observe the frass you will see that it looks different than the normal poop (I will spare you the photograph). This is the sign that your missing caterpillar has gone to find a good spot to make its chrysalis.

In about two weeks we should see a few more of these beautiful butterflies gracing our garden.

Black Swallowtail on Black & Blue Salvia
Linking to Rambling Woods for Nature Notes Wednesday. Please stop by to see observations of nature from all parts of the world.

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