Messor structor Care Guide: Keeping a European Harvester Ant
Messor structor is a European harvester ant that collects seeds, stores them in dry chambers and chews them into "ant bread" for the colony. Small dark workers forage alongside majors with big heads that crack the seeds open, so there is always something to watch. It is cared for just like the popular Messor barbarus, with one difference: Messor structor can be kept with more than one queen. Easy care and fascinating behaviour make it a great species for beginners.
At a glance
Origin: central, southern and eastern Europe
Difficulty: beginner
Colony structure: one queen or several queens together
Workers: strongly polymorphic, from small workers to big-headed majors
Growth: medium, slow at first
Colony size: large
Temperature: room temperature, gentle heat optional
Humidity: moist brood area, dry seed storage
Winter rest: recommended
Most important point: no vibrations
Appearance and size
The workers are small and dark, and the colony is strongly polymorphic. Next to the small workers you will find medium workers and majors with enlarged heads and strong jaws, which crack open the seeds. Big majors can be entirely dark brown. The queen is clearly larger than the workers.
One name, several species
For a long time, many harvester ants across Europe were all called Messor structor. In 2018 researchers looked closely at their DNA and body shape, and found that "Messor structor" was really a group of several species that look almost the same. They titled their study "Turning one into five". Species such as Messor ibericus are now seen as separate from the true Messor structor, which lives in central, southern and eastern Europe.
Where do they live?
Messor structor lives in dry grasslands, fields and other warm, open places, and sometimes in lawns and abandoned fields. As a seed eater it plays a real role in these habitats: by collecting and storing seeds, it affects which plants grow where. In some places, such as near Retz in Austria, researchers found huge networks of connected nests with many queens, which did not even hold normal swarming flights.
Colony structure
Colonies can have one queen or several queens together. Young queens start a colony after the nuptial flight and do not need food until the first workers arrive. That is why we offer this species with one or two queens.
Founding a colony
Leave a founding queen in a closed test tube until the first workers arrive. Too much space causes unnecessary stress. Our test tube guide shows how to set one up.
Growth
Growth is slow in the first months, and faster once the colony has more workers and warm conditions. Mature colonies can become large. How fast it goes differs per colony, so we do not give timelines.
No vibrations
This is the most important point for this species. Messor structor is very sensitive to vibrations, which stress the colony. Place the setup somewhere free of vibrations, such as a separate table or a wall shelf, and avoid moving or touching it more than necessary.
Temperature and heating
Messor structor does well at room temperature, and warmer conditions speed up brood development. Heating is optional. Gentle heat on one side of the nest can help a young colony grow. Always leave a cooler area so the ants can choose, and keep in mind that the setting on a heat mat is not the temperature in the nest.
Humidity
Keep the brood area of the nest moderately moist and another area dry for seed storage. Seeds that get too damp can sprout or go mouldy. Always keep clean water available.
Winter rest
A winter rest is recommended. Give the colony a cooler rest period from late autumn to early spring, for example in an unheated room. Feed less during this period, but always keep water available.
Feeding: seeds
Seeds: seeds are the main food. Young colonies without majors do best with small, soft seeds, such as our Pre-Major Harvester Seed Mix.
Small portions: do not give too many seeds at once. Sorting and storing a large pile costs the colony a lot of energy. Offer a small amount and add more when the stock runs low.
Insects: not essential, but a small insect now and then does no harm.
Sugar: not needed. Harvester ants do not take sugar water or sugar jelly.
Water: always keep clean water available.
Hygiene: remove old husks from the outworld to prevent mould.
Waste and husks
Workers store seeds in dry chambers called granaries and carry the leftover husks out of the nest to a waste pile. Because they eat seeds, harvester ants also produce hard droppings. They often smear these against the glass, and in a nest that is too large they use a whole chamber as a toilet. This is completely normal, and one more reason not to give the colony a nest that is too big.
Housing
Founding queen: a closed test tube until the first workers arrive.
First workers: connect the test tube to a Mini Outworld to give the colony a small foraging area.
Larger colonies: once the colony has a large number of workers, move it to the Avalon Ant Nest (Small Chambers version). Avoid a nest that is much too big for the colony.
Strong jaws: majors of larger colonies can chew through Ytong, plaster and even acrylic. Check stoppers and nests regularly for damage.
Escape prevention: not a strong climber, so small colonies do not need an anti-escape barrier. For larger colonies, apply Fluon to the outworld.
Is Messor structor right for you?
If you want a calm, easy species with plenty to watch, Messor structor is a great choice. Feeding is simple, the workers are harmless to people and the majors with their big heads are a joy to see. Just give it a quiet, vibration-free spot. Have a look at our Messor structor colonies, or compare it with Messor barbarus.
Sources
AntWiki. Messor structor.
Steiner, F. M. et al., 2018. Turning one into five: integrative taxonomy uncovers complex evolution of cryptic species in the harvester ant Messor "structor". Molecular Phylogenetics and Evolution.
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