On the 10th of June 2012 we noticed giant swallowtail caterpillars on our hoptree (Ptelea trifoliata). This is the earliest that we've observed them in our garden. In Southern Ontario, giant swallowtail caterpillars eat only the leaves of hoptree and prickly ash, our two native species of the Citrus family (family Rutaceae). If you want these amazing animals in your garden, you need to plant their food plants. Do it today!
Young caterpillar of giant swallowtail butterfly, "Papilio cresphontes", with everted osmeterium (photo N. Zitani, 13 June 2012)
In summer 2011 we documented numerous visits of giant swallowtail butterflies to our hoptree, beginning 8 August and continuing to 4 September. Below, watch the "orange dog" or caterpillar of the giant swallowtail evert its red osmeterium (28 August 2011).