How to ID ants?

I regularly encounter tonnes of ants, as part of my project 2021 Backyard Ant Survey. Mostly Solenopsis geminata, Myrmicaria brunnea (Likely) and Paratrechina longicornis. But how can I up the odds of species/genus ID? Even the top experts like @peterslingsby have trouble! I really need tips! Help me!

Either good photos are needed or microscope. Many genera can be ided from pretty generic photos, but usually for species id you need to see microsculpture of their bodies, head shape, mandibles, etc. But of course there’re some species that are easily ided because of unique colour or shape.
Searching for species list of your region will help you to understand how they can look and what exactly you need to capture.

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Do good old magnifying glasses work?

Of course, especially with dead ones.

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I have done quite a bit of work with ants and still have trouble on some species ID’s, especially many of the Formica sp. Like @marina_gorbunova said, the genera can usually be picked apart pretty easy and I absolutely love “Ants of North America” by Brian L. Fisher and Stefan P. Cover. I would highly recommend having this book on hand if you are into ant ID. AntWeb.org is also another fantastic online resource. *EDIT: Sorry, I see you are not in the US so this book would not be beneficial, my bad! AntWeb.org might still be helpful!

One short rant - I worked at the C. P. Gillette Museum of Arthropod Diversity in Colorado which consistently has professors and experts checking identifications. Of their entire Pogonomyrmex (Harvester Ant) collection from Colorado, 85% are occidentalis and 15% are barbatus. When you look at those same collection records via photographs on iNaturalist it’s even. 50% barbatus and 50% occidentalis. Without a microscope, I am skeptical about the accuracy of some species identifications. Some characteristics are too minute to get with a photo. (Professors and experts can be wrong too!)

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If I want to observe a small insect top, bottom, side, etc.; I chill it until it stops moving. I put the gently captured critter in a little cold dish (usually, jar lid in my case, though a Petri dish would be ideal) until it stops moving. Before it chills, while it is still active to climb out, I have a clear lid (left over from a spice jar*) I put over it.

Once it is chilled and stilled, I can take a pine needle (or tooth pick) to turn it over and look at it from different angles. I don’t use a good enough camera to really get good photos, but at least I can see the different sides for myself to learn a bit.

https://www.inaturalist.org/observations/67217938
https://www.inaturalist.org/observations/57704266
https://www.inaturalist.org/observations/52892895

I just put a cold pack* from the freezer on the table and put the dish on it to get cold. I usually put a piece of paper towel in the dish to absorb condensation.

When I’m done, I let it go and it usually warms up enough to recover and crawl off in a few minutes.

*mine was a left over, but you can buy clear lids or Petri dishes.
**Pain Cakes are handy as they have a sticky side that holds the dish in place.

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Welcome to the Forum! That’s pretty interesting about the discrepancy in ID ratios ! I wonder if the numbers are locale-biased?

Ants are pretty fascinating creatures on any level. Our neighborhood was invaded by tons of Argentine Ants last summer and fall. It was an epic effort even into the early winter to keep them at bay with cinnamon, baby powder, and baking powder. I wonder if they would be back in such big numbers as it warms up?

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