This guide was compiled and written by noebl1, sirjordancurtis, serafine of the 'Ants and Antkeeping' discord server, which can be found here. https://discord.gg/YbZGvtR3
This guide has been posted with the permission of the authors. The original article may be found here
https://www.reddit.com/r/antkeeping/wiki/caresheets/prenolepis_imparis
Caresheet - Prenolepis imparis
Prenolepis imparis, commonly known as “winter ants” or "false honeypot ants" are native to and found exclusively in North America. They are found in at least 44 of the 50 US states. Being very calm ants, they are usually found to be foraging at very low temperatures, sometimes even below freezing.
Prenolepis imparis are decent beginner ants but it takes some additional knowledge about their unique lifestyle to raise a successful colony. Also they may not fulfil the expectations a typical new antkeeper has from their colony - while the behavior during their more active periods is very interesting to observe they go through long periods of inactivity during several times of the year while feeding from resources stored in the bloated gasters of their repletes. Unlike other ants which may get extremely defensive or stressed out though, Prenolepis imparis are very serene ants and also quite receptive to food, never passing off the chance to drink some more sugar water or honey - so if you're looking for a relaxed timid ant that doesn't need constant attention this may be the perfect ant for you.
Taxonomy
-Family: Formicidae
--Subfamily: Formicinae:
---Tribe: Lasiini
----Genus: Prenolepis
-----Species: Prenolepis imparis
Basic Information
Origin: Northern America - South Canada (Ontario), United States, Mexico
Habitat: Prenolepis imparis digs nests in the ground many feet deep, depending on how hot the climate of their environment is. In Florida, one colony was found to have made a nest of more than 3.6 meters down from surface level. While most colonies in other states do not dig that far they rarely have chambers shallower than 60 centimeters.
Colony form: Queens can form polygynous colonies, with records of ant-keepers successfully keeping colonies of even up to 9 queens.
Colony size: The worker count of multiqueen colonies usually maxes out around 10.000 ants over the course of 7-9 years. Colonies with a single queen may remain smaller.
Founding: Queens of this species are fully claustral and do not require any form of food before their workers arrive (they still need water obviously).
Workers: Monomorphic.
Hibernation: Prenolepis imparis are most active during cold times of the year. There's a debate on whether they have a winter hibernation or not.
Summer inactivity: Prenolepis imparis has an estivation period during the hot months of the summer, ranging from 3 to even 8 months in hotter and more humid climates like Florida. During this time the colony shows almost no foraging activity living exclusively from the food stored by their repletes, however eggs are laid and brood is raised.
Reproduction: Female and male alates fly around mid January to March, with the largest flights around early February.
Appearance
Worker: Workers are of a light brown coloration, with most of the workers of this species having gasters that make up half of their body length.
Queen: Queens are of a light brown, and when they consume foods which are colored, the coloring of the food can be seen through the gaster. Queens sometimes may have a noticeable spot of orange on their thorax.
Males: The male alates for Prenolepis imparis are usually much darker in color and much smaller than the queens, with a very thin and pointy gaster.
Size
Workers: 3.0-4.5 mm
Queen: 7.0-8.5 mm
Males: 3.0-4.0 mm
Development period
The development period for winter ants actually varies a great deal, as the brood time for Prenolepis imparis is known to ant-keepers to notoriously vary and take very long periods of stagnation during the founding stage.
Egg to Larva: 3-4 weeks
Larva to pupa: 3-4 weeks (4-5 weeks during founding period)
Pupa to Worker: 2-3 weeks
Ant-keeping information
Recommended for beginners: Sort of. They aren't hard really to raise but require some knowledge about their unique lifestyle and activity schedules as they are in many ways different from any other ant species.
Temperature: around 8-15°C during spring and fall, up to 25°C in the summer (including estivation), around 0-5°C during winter hibernation
Humidity: room humidity in the outworld, slightly moist in the nest
Nest types: farm nest, outworld nest, ytong, sandstone
Formicarium size: Should fit the current colony size.
Formicaruim accessories: -
Substrate type: sand-clay bottom layer
Behavior
Another name that is given to Prenolepis imparis is “false honeypot ants” because they also form repletes, or corpulents within the colonies, which can store more than twice their own weight in food. However, the corpulents of Prenolepis imparis are not true repletes, as their enlarged gasters are mostly made of hypertrophied fat bodies storing protein and fat, unlike the repletes of honeypot ants which usually use enormously enlarged social stomaches to store liquid sugars and water.
These ants react well with other members of the same species, even when they are not from the same colony. On many accounts of antkeepers, it is also possible to conjoin two different colonies of Prenolepis imparis. They like to form long trails which can extend many meters away from the original nests, although they usually have the most successful nests at the base of trees and directly forage on the tree.
False honeypot ants are active during the day but tend to avoid bright sunlight and prefer a cloudy/shadowy environment. Workers can forage at temperatures as low as -3°C (27°F). They are most active at temperatures between 1.5°C (35°F) and 13°C (55°F). At temperatures above 15°C (60°F) they usually do no longer leave the nest.
Additional Information
These ants are relatively calm to handle compared to other ants, mostly having very little activity through out the year. Queens during their founding staged can be stressed by over-observing and may consume their eggs, but once established colonies are less fragile. People often comment that they are quite boring ants due to the their relaxed behavior. Due to of their ability to store forms of liquid foods, they are known for not needing a lot of constant attention, and depending on the size of the colony, do not actively need large amounts of food all the time. Monitoring their repletes and foraging activity is a good indicator for when feeding is required.
This ant is often kept by beginners as one of the first species to fly in most regions. However it’s often a challenge for new ant keepers to keep into the 2nd year as many not lay again, and the colony eventually fails. Antkeepers have observed they may not lay eggs until shortly before or during their summer estivation period. While they are in estivation, the whole colony including any brood is living entirely off the repletes, with no foraging occuring.
There are several ideas on why they may not be laying into their second year. It’s been reported that having a short hibernation of 1 to 3 months during the winter seems to help. After coming out of this hibernation, offer protein in addition to sugary foods even if no brood is present. It’s important for them to prepare for estivation. If they don’t go into estivation with enough resources, like with resources needed before hibernation, the colony may fail to lay, or even starve. Length of estivation may vary based on climate. In colder areas estivation may only be a few weeks, while in warmer areas, it can be several months.
There have been statements that P. imparis requires cold temperatures year around in order to be successful. However many antkeepers keep them at 25°C or higher during the summer and the colony is successful. During the short winter hibernation, temperatures of 7°C seem sufficient for them to have a winter rest period as well.
Alates are usually reared during the late summer and stay in the nest over the winter months. Male alates are substantially smaller and differently colored from the queens, which is why the ants were given them name “imparis.”
There is a mycrogyne form of P. imparis queens that flies during autumn but only two specimens were ever collected and it is unclear whether this is an actual P. imparis queen form, a social parasite or even an inquiline (workerless social parasite).
Diet
Prenolepis imparis is an opportunistic omnivore. Most of their food consists of liquids ranging from nectar and the sugary excretions of aphids and other plant-sucking insects over the body fluids of freshly-died insects and earthworms to juices sapped from fruits and young plant sprouts.
They are not known to be notoriously picky, although they have different choice selections regarding feeding protein. Their typical natural sources of protein in the wild include small arboreal insects, and annelids, including earthworms. They feed on nearly any type of sugars provided to them.
In the wild winter ants often eat dead or dying earthworms driven to the surface by rain. They seem to be able to remember the position of dead earthworms and return to them everytime after a rain as long the carcass is still present.