Hi Erin,

Is it possible to send some close up pictures of the beetle, larva and defoliation?

Thank you for sending pictures.  I need a bit more help...

I see the beetle, black "sac" type things and some caterpillars.  

Here is information about the sumac flea beetle https://extension.usu.edu/pests/ipm/ornamental-pest-guide/arthopods/leaf-beetles-weevils/sumac-flea-beetle.    Did I miss larva that looks similar to the ones in the picture?

I am wondering if the "caterpillars" are eating the leaves?  Removing the caterpillars by hand will obviously prevent them from eating more leaves.

I want to send your pictures to an insect specialist to confirm identification.  Once we have that information we can figure out a plan for insect control.

I inadvertently closed the question.  I need to reply this way to keep it open.

Sorry!

Here is the email I received from a Master Gardener extraordinaire after he confirmed that flea beetles are what is eating your plant:

The real question is whether in fact any pesticide should be used?

1). The damage done by the larvae is largely cosmetic. It would not be expected that the sumac is endangered and/or its survival threatened.

2). The window of opportunity for using a larval pesticide is right after the larvae hatch from the eggs. Given the rather large size of the larvae in the picture and the presence of adult beetles would suggest that this window has largely passed.

3). Most pesticides effective against sumac flea beetle larvae may also have a detrimental effect against the larvae/caterpillars of desirable insect pollinators.

Nevertheless, see the following:

https://extension.usu.edu/pests/ipm/ornamental-pest-guide/arthopods/leaf-beetles-weevils/sumac-flea-beetle - :~:text=Pesticides are not typically needed,hatch to control young larvae.

https://www.grit.com/farm-and-garden/pests/battling-the-evil-flea-beetle/https://www.grit.com/farm-and-garden/pests/battling-the-evil-flea-beetle/

https://www.maine.gov/dacf/php/gotpests/bugs/factsheets/flea-beetles-col.pdf

I hope this helps.

I think you are right to think that you should just let plant go for this year, but there are some things you can do in the fall to "battle the enemy".   This article has several suggestions: https://www.grit.com/farm-and-garden/pests/battling-the-evil-flea-beetle/.

Keep the life cycle in mind.  If you are able to pick off the larva you will disrupt the life cycle!

Here is another article that may be helpful:https://getbusygardening.com/controlling-flea-beetles/#:~:text=Diatomaceous%20earth%20(DE)%20is%20another,of%20glass%20to%20kill%20them

Good luck.  LEt me know if you have any more questions.