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Care Sheet - Forelius mccooki

forelius mccooki

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#1 Offline Crystals - Posted February 27 2015 - 7:38 AM


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Scientific Name:  Forelius mccooki
Common Name: 

Distribution:  Southwestern United States.

Queen size:  5-6 mm

Worker size:  2.5 mm

Natural Habitat:  Lower elevation mountains, Arid-land, sand dunes, river beds and out in the eastern California deserts.

They tend to live anywhere hot and dry that has open space that gets a lot of sun. They commonly nest under rocks.

Circadian Activity:  Diurnal
They completely disappear most nights. Very rarely have I seen them active at night.

Mating Flight:  Unknown.
I have, however seen alates in the summer months. And I have seen them bud out their colonies in August, so I assume that is their main "flights". They do not from what I have seen, ever fly like most ants.

Queen Founding Method:  From what I have seen, they take some workers and make a new nest that is then connected to the main colony.
Monogyne or Polygyne:  Polygyne
Lots of queens. One colony that was disturbed by construction, under a boulder had at least 500+ queens (HUGE piles of living queens), but that must be rare though.

Average time from egg to worker:  Egg to worker takes 1 month in 70-80 degree fahrenheit temperatures, and the colonies grow VERY fast (a bit faster or as fast as Solenopsis invicta).

Recommended Temperature:  70+ degree fahrenheit, optimal is 80 degrees fahrenheit.
I personally have seen them on pavement in 120 degree weather, out in the full heat of the desert sun.

Recommended Humidity:  Very dry, but access to water.
I misted mine once every 2-3 days, depending on how much they were getting the water.

Preferred Foods:  Anything.
The question is actually, what will Forelius pruinosus/mccooki NOT eat? Everything I threw in my colony they devoured. They eat more variety of foods than my Argentine ants and Solenopsis invicta ate.

This species does have a social stomach.

Hibernation Details:  Optional. Out in the desert in the Salton Sea (far southeast California), they are active in 40 degree day time temperatures with a VERY cold winter storm Wind (it was sunny still). Near the coast, they tend to disappear. One large colony remained active though near the coast. Then again, Forelius pruinosus/mccooki are actually many species in one, that the ones in the Salton Sea may behave very different and are completely different species than the ones on the coast. However, I never had to hibernate even the coastal ones.

Escape Barrier Methods:  Be sure to have a good escape proof barrier. They are FAST and very good climbers.

Difficulty rating:  9/10

Easiest ant species I've ever had, the most active and grew VERY quick. However, because of how fast they grew, the easiness goes from 10/10 to 9/10. I still, however have never had kept such a easy, hardy (almost NOTHING kills them, except mites) ant species since my multiple Forelius colonies. They are easier than Solenopsis invicta, Argentine ants and every other "easy" ant I've had. They require very little maintenance, at least a source of water as they prefer it dry, eat a lot and pretty much take care of themselves. Even though they are fast and good climbers, I still found them very easy.

Also, after a few months in captivity...they adapted really quick and were A LOT less prone to escaping when I opened the lid. They actually became really relaxed and laid back ants.

Bite and/or Sting rating:  No sting or bite.

Special Care or Interesting Notes:  A bit of space for when they grow, since they grow really fast.

They also make amazing looking trails. Long, thick, fast moving trails. With a bit of a mound as well for their nest entrance if you are using substrate. Also, they WILL produce alates and breed in captivity. They also seem to make "supercolonies", as mine had queens in all 6 containers I had connected up. Also the colony I got them from, had WAY over 500 queens under a boulder pulled up from construction. They even managed to drive out the Argentine ants till bulldozers came. Their colony was spread over a HUGE area.

Another colony in the Salton Sea is also really huge, with over 100 queens and in a large area.

Additional Links:
Information submitted by Vendayn.

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List of Handy Links   (pinned in the General section)

My Colonies

#2 Offline Vendayn - Posted February 27 2015 - 8:38 AM


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Hope this helps anyone who may want to keep them. :) Not many people tend to keep Forelius. They are some of my favorite native ants found in California. Very easy to keep, but not boring at all.


Also, for those who will probably ask. The mass amount of queens huddled together was probably because the entire area around them had been bulldozed to a few remaining boulders. Forcing them all in one spot. The colony at one point had a HUGE area they traveled in. Not sure what the colony is doing now, but last I knew, they had evacuated to the nearby neighborhood and drove off the Argentine ants there. But, that was almost 2 years ago.


The colony I've been watching over the years down in the Salton Sea has been there for a long time. They have tons of ants, easily over 10 million and countless queens. I have a feeling in urban/disturbed areas they might become "invasive" like Tapinoma sessile do.


In any case, they are great ants to keep. They are so easy to find, but no one really notices them for the most part.

Edited by Vendayn, February 27 2015 - 10:32 AM.

#3 Offline JWRay - Posted June 8 2016 - 7:57 PM


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Very nice guide.  I am really glad I stumbled across this website, as I am gaining a whole new appreciation for ants and there is a nice breadth of knowledge and interests of the members here.


I have not collected all that much in CA yet, but I have not yet even found this genus - so I must be doing something wrong.


One question, by a 'bit of space for when they grow', how large of an enclosure/system are we talking to maintain these guys?

Edited by JWRay, June 8 2016 - 7:57 PM.

#4 Offline Vendayn - Posted June 25 2016 - 7:50 PM


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I see this was posted on the 8th, hopefully this is still helpful.


Forelius mccooki (and pruinosus) actually need more foraging space than actual living space. In their natural environment, they explore pretty far. I often see their trails going for quite a ways. Their living space actually isn't that big, even in their main nests. The colonies in the wild don't nest deep, and they don't have tunnels all over like some ants. They don't take up much room underground at all, most of them are out foraging. The information was a tad bit wrong there when I posted it. Thinking back on it after experience with a couple other ant species, the information changed a bit.


Hope that helps. :)

#5 Offline AntsNmyPants - Posted August 26 2019 - 9:56 AM



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Hello, I think I may have some elates and workers from a wild Forelius mccooki colony. My son found them hanging out at the nest entrance in the middle of the afternoon. I originally thought they were Argentine ants but upon further inspection I am beginning to think I was wrong. My question is, if they are indeed Forelius mccooki, do they need a nuptial flight to breed with foreign colonies or can they breed within their own colony and sustain?

#6 Offline FeistysWitch - Posted July 2 2020 - 7:45 AM



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This may be somewhat late to the topic but I recently captured some Forelius queens. Their nuptial flights here in South eastern New Mexico seem to be in summer following the rainstorms. It was late June when I caught them. They seem to start flying early morning and will be out all over the place. Other ant species, specifically p. Rugoso and Novomessor sp. seem to also come out in droves to predate on their flights. I have also observed the same behavior from various harvester ant species during termite nuptial flights.
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