Lasius sitiens Species Introduction
Claustral. No food is needed until the first workers are running. The odd part is that no nuptial flight has ever been recorded for this species. Reproductives have only been found inside nests, on six occasions between the second and thirtieth of July. If you are collecting rather than buying, July is the month and the nest is the place to look.
A southwestern mountain ant, described by Wilson in 1955 from juniper scrub north of Flagstaff and known from Arizona and New Mexico through Utah, Nevada and Texas into northern Mexico. It keeps to the lower forest belts, roughly 6,400 to 8,000 feet, nesting almost exclusively under stones in dry open ground. Everything about the worker says underground: yellowish brown, appendages noticeably shortened, and eyes carrying about 11 ommatidia where niger-group relatives carry 14 or 15. At the type locality Wilson could not find a single worker foraging above ground, by day or in the early night. Nests also share a stone with five other ant species, a lot of sharing for a Lasius.
An ant for a keeper who is genuinely interested in what happens underground, because that is the only place anything happens. Lasius sitiens is a niger-group Lasius that has evolved the body of a subterranean: pale, short-legged, nearly blind. Expect an empty outworld as the permanent normal state and judge the colony by its nest. What ends colonies is the winter. This is a mountain ant from 6,400 feet and up, and one pushed straight through a warm winter will stall.
Formicarium
Give them depth and darkness. The wild nest is under a stone in dry open ground, so a Substratum Sand Ant Nest or any deep substrate nest reads right, and the colony will use vertical space rather than spreading out. Keep the nest covered by default. A fluon barrier is worth having, but these are not ants that test it much.
Water & Humidity
Fairly humid, with the moisture where they actually live. Nests sit under stones in sandy, loamy and rocky soils, and the brood is kept well below the surface where damp holds. Water the deep end generously and let the top run dry the way ground under a sun-warmed rock does. Dry throughout is the one arrangement that will not work.
Recommended to use TrapJaw Labs PVA sponges during founding for improved success rates and more nanitics. Keep the tube dark as well as damp, as this is a species with no use for light at any stage.
Keep a liquid feeder with water (distilled, purified, or spring) in the foraging area at all times. Put it where the tubing meets the nest rather than out in the open, because a feeder in the middle of an arena they never cross does the colony no good.
Carbohydrates
Carbohydrates lead, as they do across Lasius. A colony that never surfaces is not working nectar, so whatever sugar it finds in the wild comes from below ground, and that is worth remembering when you decide where to put the feeder. We recommend providing sugar-water (we use our Ant Nectar Mix) and fresh-water liquid feeders in the outworld at all times.
Occasional small honey drop in the outworld is fine, though out there it will usually go untouched. Offering it just inside the tubing works considerably better.
Site the feeder close to the nest connection and judge use by the level rather than by watching for traffic. You will rarely see a worker at it even while it is going down.
Protein
Protein is the smaller half of the diet, but it still has to arrive. Offer small pre-killed items two to three times a week and place them near the nest connection rather than out in the open. Clear anything untouched, because food left in a humid setup for a colony that never collects it turns into a mold problem.
TrapJaw Labs feeds our L. sitiens colonies with pre-killed D. melanogaster and D. hydei fruit flies and pre-cut mealworms. Cut items small and put them where the ants actually go. A whole insect left in the middle of an arena will still be sitting there a week later.
Two to three times per week. Increase amounts to scale with brood development.
Maintenance
Week 1: Seal her in a test tube with a PVA sponge, keep it dark, and do not open it. No food is needed. Darkness matters more for this one than for most, so wrap the tube rather than trusting a closed drawer to do the job.
Weeks 6–8: First workers ('nanitics') appear. Start a sugar feeder and small protein items two to three times a week, sited close to the nest. Do not expect to see much. A healthy small colony of this species shows you a brood pile and very little else.
Months 2+: Steady, quiet growth. Move them up at about 75% of the nest space in use, favoring depth over floor area. Judge progress by the size of the brood pile and how much of the nest is occupied, because a worker count taken from the outworld will always read as zero.
Diapause may be required for this species. Lasius sitiens is a mountain ant, described from between 6,400 and 8,000 feet, and the range reaches the northern Rockies, so what a colony needs follows where it was collected rather than the species. Stock from the lower Arizona and New Mexico end should get 8–10 weeks from November at 45–55°F, while colonies from higher ground or further north want 12–14. Remove supplemental heat but keep liquid food and water sources fully-stocked, and keep the nest damp while it is cool.
Care Summary
- Diapause length follows where the queen was collected, not the species
- An empty outworld is PERMANENT and normal, judge by the brood pile
- Feed close to the nest connection, not out in the open
- Carbohydrates available 24/7
- Protein 2–3×/week, cut small
- Deep damp nest with a drier top, and keep it covered