Lasius emarginatus
Temperature
22–28 °C
Humidity
50–70%
Colony size
3,000–15,000
Queen size
7–9 mm
Worker size
3–5 mm
Hibernation temp
10 °C
Diet
Care Guide
Lasius emarginatus is a charming and resilient ant species, well‑suited for keepers taking their first steps into the hobby. Its scientific name hints at the notched margin of the worker’s head, but it’s the ant’s adaptable nature and striking two‑toned colouration—rich brown to black with lighter legs and antennae—that make it a pleasure to observe. Queens measure 7–9 mm, while workers range from 3–5 mm, and a mature colony can reach several thousand individuals without ever becoming overwhelming.
Care difficulty
Keeping Lasius emarginatus is remarkably straightforward, making it an excellent choice for beginners. The ants are claustral founders: after mating, the queen seals herself in a small chamber and raises her first workers entirely on her own metabolic reserves. No feeding is needed during that period, which lasts several weeks. Once the first nanitics appear, the colony quickly becomes active and undemanding. They are not picky eaters and thrive on a simple diet of sugar water or honeydew alongside protein from small insects like fruit flies, mealworms, or cricket pieces.
Housing
Lasius emarginatus is a versatile nester that adapts well to most formicarium designs. A setup with a dry, heated outworld and a connected nest chamber with moderate humidity (50–70%) works perfectly. The ants appreciate a temperature gradient between 22°C on the cooler side and 28°C near the heating source. They are not overly sensitive to light or vibrations once established, but like all ants, they do best when given a quiet corner away from constant disturbance. A small test tube setup can serve as an excellent starter nest, and the colony can later be moved to a larger acrylic or plaster formicarium as it grows. One of the most important requirements is a proper hibernation period: from late autumn to early spring, the colony should be kept at around 10°C for 3–4 months. Without this cool rest, the queen may stop laying eggs and the colony’s growth will stall.
First days after purchase
When your Lasius emarginatus colony arrives, place the transport tube or nest into the prepared formicarium in a calm, dimly lit room. If the ants are in a test tube, you can simply connect it to the outworld with a piece of tubing. Offer a drop of sugar water on a small cotton pad and a tiny insect. For the first few days, avoid opening the setup unnecessarily. Let the ants explore their new surroundings at their own pace. You will soon see them foraging, tending the brood, and stashing food. Regular, gentle observation will reveal a busy, self‑sufficient community—one that rewards patience with fascinating glimpses of daily ant life.