Subject: Tiger Swallowtail caterpillar
Geographic location of the bug: Montrose Colorado US
Time: 12:31 PM EDT
Your letter to the bugman: I found this today and had the darnest time identifying it – until I found your site. It is the last caterpillar stage to pupating. Beautiful caterpillar. I moved it to a safer location from the sidewalk so it will survive. Thought the group would enjoy the photo.
How you want your letter signed : Claudette
Thanks to your inquiry, Daniel the webmaster got Daniel the Bugman to check the What’s That Bug? email account and post your Patreon request which is the first identification request he has posted since November. This is indeed a caterpillar of one of the Tiger Swallowtail species and the orange color indicates that it is prepupal, meaning reading to undergo metamorphosis. Daniel must do some research to try to determine the most likely species. According to a comment posted to BugGuide: “Colorado has both Eastern and Western Tiger Swallowtails. If you were west of the Great Plains in or near the mountains, it would likely be a Western Tiger. East from the mountains in the towns and along the ‘rivers’ of the Great Plains, you can see Eastern Tigers just like the ones in Texas, Nebraska, or Virginia. However, the most common Colorado species in the lower lying areas along either side of the mountains (say Pueblo, Denver, Grand Junction, etc.) is the Two-tailed Swallowtail, which also looks similar. And in the mountains there are also Pale Tiger Swallowtails (usually almost white). So, Colorado has four species of Tigers, and you could see all four in or near to Colorado Springs.” Identifying the different species by caterpillar alone is beyond our expertise. We are not sure exactly where Montrose Colorado falls in the above description, but that could help you pin down which of the four Tiger Swallowtail species that are reported in Colorado you encountered.