Myrmica crassirugis

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Western North America, from southern Canada through the western USA including Idaho, Nevada, Utah, Montana, Oregon, and eventually Arizona, California, New Mexico, Wyoming, and southern Alberta. Found in semi-xerophilous prairie (sagebrush habitats) and open dry coniferous forest of the upper Sonoran zone in mountains. Nests in mineral soils at elevations ranging from 880m in Oregon to over 3000m in Nevada ^[1].
• Colony Type: Likely monogyne, most Myrmica species have single-queen colonies, though specific data for M. crassirugis is lacking.
• Size & Growth:
  • Queen: Approximately 8-11mm, inferred from Myrmica genus patterns since total length measurements are not available ^[1]
  • Worker: Approximately 4-6mm, inferred from Myrmica genus patterns since total length measurements are not available ^[1]
  • Colony: Unknown maximum, estimated from related Myrmica species to reach several hundred to a few thousand workers
  • Growth: Moderate, estimated from Myrmica genus patterns
  • Development: Unknown, development time has not been documented for this species (Development timeline is unconfirmed. Related Myrmica species typically take 6-10 weeks at room temperature.)
• Antkeeping:
  • Temperature: Room temperature around 20-24°C is suitable. This species comes from mountain habitats with variable temperatures and can tolerate some variation. A slight temperature gradient in the nest is beneficial but not required.
  • Humidity: Moderate, these ants live in semi-xerophilous (dry to moderately dry) habitats. Keep nest substrate moderately moist but allow it to partially dry between waterings. Provide some drier areas within the nest for the ants to choose.
  • Diapause: Yes, likely required based on northern distribution and mountain habitat. Provide a winter diapause of 2-3 months at 5-10°C during winter months.
  • Nesting: Nests in mineral soils in the wild, either uncovered or under rocks and vegetation. In captivity, a naturalistic setup with soil or a Y-tong/plaster nest works well. They prefer compact soil chambers rather than overly loose substrate.
• Behavior: Myrmica crassirugis workers are active foragers that defend their nest moderately when threatened. They can sting, which causes mild pain and irritation but is not dangerous to humans. They are not known as escape artists but standard barrier methods should be used. Workers forage for nectar, honeydew, and small insects.
• Common Issues: limited availability, this species is rarely available in the antkeeping hobby since it was only described in 2007, cryptic habits mean wild colonies are difficult to locate and collect, winter hibernation is likely required but specific timing and conditions are unconfirmed, lack of species-specific care information means keepers must rely on genus-level guidance, queen founding may be difficult since colony structure data is lacking

Natural History and Distribution

Myrmica crassirugis is a western North American species found from southern Canada through the western United States. It should eventually be found in Arizona, California, New Mexico, Wyoming, and southern Alberta based on suitable habitat ^[1]. This species lives in semi-xerophilous prairie habitats similar to sagebrush steppe and in open, dry coniferous forests of the upper Sonoran zone in mountains. They have been collected at elevations ranging from 880 meters in Oregon to over 3,100 meters in Nevada ^[1].

In the wild, foragers have been collected on various plants including Atriplex confertifolia (shadscale), Agropyron cristatum (crested wheatgrass), Pterysia terebinthina, Balsamorhiza sagitta (arrowleaf balsamroot), and Pinus species (pine trees). Nests are dug directly into mineral soils, either in the open or concealed under rocks and vegetation like herbs and shrubs. Despite their cryptic habits, researchers found them across all major soil and vegetation types at the Idaho National Engineering and Environmental Laboratory site ^[1].

Identification and Distinguishing Features

Myrmica crassirugis workers are small ants approximately 4-6mm in length. They can be identified by their rounded head (slightly longer than broad), strongly and deeply striated mesosoma with longitudinally aligned rugae, and medium-length propodeal spines that are subparallel and slightly surpass the propodeal lobes. The body color ranges from light to dark brownish-red, with the mesosoma often appearing more reddish than the head and gaster ^[1].

This species belongs to the Myrmica crassirugis species group, which was established by Francoeur in 2007. It was previously misidentified as Myrmica americana, Myrmica latifrons, or Myrmica lobifrons in collections. A chemotaxonomic study in 1991 showed that M. crassirugis is distinctive from 14 other described Nearctic Myrmica species and shares some similarities with European species ^[1]. The species name 'crassirugis' comes from Latin meaning 'thick wrinkle, ' referring to the distinctive coarse sculpture of the mesosoma.

Housing and Nesting Preferences

In captivity, Myrmica crassirugis does well in naturalistic setups with mineral soil or in Y-tong/plaster nests. Since they naturally nest in mineral soils, a compact soil-based formicarium mimics their wild conditions well. Keep the nest substrate moderately moist, these ants come from semi-xerophilous habitats, so they prefer drier conditions than many Myrmica species but still need some moisture. Allow the substrate to dry partially between waterings, with some areas remaining damp.

Provide a standard outworld for foraging with access to sugar water and protein sources. Room temperature around 20-24°C is suitable, with some flexibility since they inhabit variable mountain environments. Standard escape prevention (barrier gel or fluon on edges) works well for this species, they are small enough that standard precautions should be taken.

Feeding and Diet

Like other Myrmica species, Myrmica crassirugis has an omnivorous diet. In the wild, foragers have been collected on various plants, suggesting they collect nectar and honeydew. They probably also hunt small insects and arthropods for protein.

In captivity, offer sugar water or honey as a constant energy source. For protein, provide small insects like fruit flies, pinhead crickets, or mealworms. Based on related Myrmica species, they should accept a variety of foods. Feed protein 2-3 times per week depending on colony size, and keep sugar water available at all times. Remove uneaten prey after 24-48 hours to prevent mold.

Seasonal Care and Hibernation

Based on their northern distribution and mountain habitat, Myrmica crassirugis requires a winter hibernation period. In captivity, provide a diapause (winter rest) of 2-3 months during the winter months. During hibernation, keep colonies at cool temperatures between 5-10°C, such as in an unheated garage or basement.

Reduce feeding before hibernation and stop providing sugar water during the cold period. The colony will become less active as temperatures drop. This species should not be kept warm year-round, the hibernation period is important for their health and reproductive cycle, as with other temperate Myrmica species.

Frequently Asked Questions

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References