Hi Allyson, could you open the leaves and see if there is something living inside? There are some types of caterpillars that will tie leaves together like this with silk, but also some types of damage of emerging buds can sometimes stick leaves together. If you could dissect open that section it would help diagnose the issue.

Thanks!

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Hi Allyson, that does sound like there was some kind of caterpillar in there, the black stuff may be "frass" (fancy word for bug poo/debris). In the future feel free to reach out if you see it again, if you can get a picture of the critter inside we may better be able to tell what might have caused it. 

Do you think that would have been like cocoon of sorts? I could look for caterpillars on the fireweed but that would be silly if whatever is in there has since flown away. 

Sometimes it's not necessarily a cocoon, some caterpillars will use the silk to tie up the leaves like that to help protect them from predators while they are eating. As far as cocoons, some of them will pupate directly on the host plant but others will drop down to the soil and burrow beneath the surface to make their cocoons/pupate. 

Larvae can be tricky - there are some that are recognizable due to unique markings or other features but many of our caterpillars are not very well-known so often we have to try to rear them to adulthood to get a good identification for them.

Thank you for all the info.