Dorymyrmex grandulus Species Introduction
Fully claustral and monogynous. A single queen founds alone, sealed in with no food needed until the first workers are running. Monogyny is established for this species rather than assumed, so do not pair queens on the theory that most small dolichoderines will tolerate it.
An eastern pyramid ant, from Alabama and northern Florida up the seaboard to the New Jersey Pine Barrens. Habitat is woodland and the open ground beside it: pine-oak forest on clay and sandy soils, dunes, and the edges of temporary ponds. Colonies are monogynous, and workers are small even by the standards of the genus, yellowish brown to almost black under a grey pubescence that gives them a mousy look, on hind tibiae longer than head and mesosoma together. The best part is the name: Forel described it in 1922 as a variety of an ant in an entirely different subfamily, calling it grandula because it was the larger of the two.
A small, quick, unfussy pyramid ant for someone who wants constant activity without a large setup. Colonies stay manageable and the ants are almost never still. Two things cost people colonies here. The first is the nest drying out, because this is a genus that keeps its brood in damp soil and has no answer to a formicarium that runs dry. The second is escape. Workers are barely 2mm and fast, and they find a lapsed barrier long before you notice there is one.
Formicarium
A Substratum Sand Ant Nest suits them, as does any substrate nest that holds moisture, since the wild nest is in soil rather than wood. Give more floor than height. Containment is the part to take seriously. These are 2mm ants that move quickly, so seal every fitting, put fine mesh over vents, and keep a fluon barrier current rather than topping it up when you remember.
Water & Humidity
Very humid at the nest. This one turns up on pine-oak clay and at the edges of temporary ponds, ground that holds water below the surface long after the top has dried. Keep the nest damp end to end and let the outworld do what it likes. If the brood pile is shrinking rather than growing, check the water before you change anything else.
Recommended to use TrapJaw Labs PVA sponges during founding for improved success rates and more nanitics. A queen this small dries out quickly, so keep the sponge charged.
Keep a liquid feeder with water (distilled, purified, or spring) in the foraging area at all times. It is recommended to use the TJL Liquid Feeder for these tiny ants as the mesh prevents accidental drowning.
Carbohydrates
Carbohydrates do most of the work. Pyramid ants are high-energy foragers that run almost constantly, and the sugar feeder is what pays for it. We recommend providing sugar-water (we use our Ant Nectar Mix) and fresh-water liquid feeders in the outworld at all times. A colony that has gone quiet is often just a colony that has run its feeder dry.
Occasional small honey drop in the outworld is fine. Keep it small and on something you can lift out, because at this worker size a drop that goes untouched becomes a trap rather than a meal.
Check the feeder daily. This is a genus that empties one faster than the colony size suggests it should, and the check takes seconds.
Protein
Protein matters more here than it does for most dolichoderines. These are active foragers with a brood pile to keep fed, and they take insect protein readily rather than needing to be tempted into it. Offer small items and clear what is left, as an uneaten insect in a nest kept this humid will mold quickly.
TrapJaw Labs feeds our D. grandulus colonies with pre-killed D. melanogaster and D. hydei fruit flies and pre-cut mealworms. Keep the pieces small. A 2mm worker cannot do much with a whole feeder insect, and the colony will strip a cut piece far faster.
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 undisturbed, and offer no food. Check that the sponge is still wet rather than checking on her. A queen this small has very little margin if the tube runs dry.
Weeks 3–5: First workers ('nanitics') appear. Put out a stocked sugar feeder straight away and begin small protein items two to three times a week. Growth is quick from here compared with most of what we keep, and the barrier becomes a real job the moment they are out of the tube.
Months 2+: Fast, busy growth with plenty of visible foraging. Move them up at about 75% of the nest space in use, keeping the new nest humid from the day they go into it. Re-apply the fluon barrier on a schedule rather than waiting for the first escapee to tell you.
Diapause may be required for this species. Dorymyrmex grandulus runs from the Gulf states to the New Jersey Pine Barrens and possibly further north, so what a colony needs follows where it was collected rather than the species. Southeastern stock does not need a winter. Colonies from the mid-Atlantic and the Pine Barrens should get 8–10 weeks from November at 50–60°F. Remove supplemental heat but keep liquid food and water sources fully-stocked, and do not let the nest dry out while it is cool.
Care Summary
- Nest humid at all times, the outworld can run dry
- Containment is a real job, these are 2mm ants that MOVE
- Sugar feeder stocked and checked daily
- Protein 2–3×/week, cut small
- Gradient 75–90°F, warm foraging end and a cooler nest
- Diapause follows where the queen was collected, not the species