Insect, Spider and Kin Guide

This guide initially displays common arthropods (insects, arachnids, centipedes/millipedes and crustaceans) of all shapes. Use the selectors below to include rare species, select by shape, or search by name.

Arthropods include several different classes: hexapods, arachnids, myriapods and crustaceans. An arthropod is an invertebrate animal with bilateral symmetry, an external skeleton, a segmented body, and jointed appendages arranged in pairs. In order to grow, arthropods have to molt, shedding their whole exoskeleton all at once.

Insects, which comprise the vast majority of hexopods, all have three basic body parts. The head has compound eyes, mouthparts, and antennae that are used as sensory organs. The thorax or mid-section typically has two pairs of wings, if the insect can fly, and three pairs of legs for a total of six. The abdomen contains the insect’s digestive system, reproductive organs and sting organs, if present.

While spiders make up the largest group of arachnids, others in the class include scorpions, harvestmen, ticks, mites, pseudoscorpions and solifuges. Arachnids have eight legs plus two additional pairs of appendages: chelicerae used for feeding and defense and pedipalps which function as a sensory organ or in reproduction. Arachnids do not have antennae or wings and have two main body parts with the head and thorax fused into one. In addition, they have two different types of eyes for a total of eight.

Centipedes and millipedes make up most of the myriapod species. They are best known for their long, segmented bodies with multiple legs, though far fewer than their names imply. In addition, they have a single pair of antennae, simple eyes, and mouthparts on the underside of their bodies.

Most crustaceans are free-living aquatic animals but a few are terrestrial such as the woodlice. Their bodies are composed of segments that are grouped into three regions: head, thorax and abdomen. Each body segment may have one or more pairs of appendages which serve as antennae, mandibles, maxillae, legs and tail.

Over 80% of all living animal species are arthropods. They occupy all kinds of roles: predators, prey, parasites, hosts, herbivores and decomposers and live in all different types of habitats. Many are particularly adapted to life in a dry environments like that of Southwest. This guide focuses on many of the common arthropods in the greater Los Alamos area. However, please note that insects in the Lepidoptera order are discussed separately in the Butterfly and Moth Guide.

Insect, Spider and Kin References

A Checklist of Plant and Animal Species at Los Alamos National Laboratory and Surrounding Areas
A Guide to Arthropods Bandelier National Monument, National Park Service [PDF]
American Arachnological Society
Arnett, RH, Jr. 2000 American Insects: A Handbook of the Insects of America North of Mexico CRC Press
Encyclopedia of Life
Field Guide to Insects and Diseases of Arizona and New Mexico Forests, US Forest Service [PDF]
Grasswitz, T.R. and Dressen, D.R. Pocket Guide to the Native Bees of New Mexico [PDF]
Grasswitz, T.R. and Dressen, D.R. Pocket Guide to the Beneficial Insects of New Mexico [PDF]
A Manual of Grasshoppers of New Mexico
Insect Identification, New Mexico
Mackay, W. and Mackay, E., 2001 The Ants of New Mexico (Hymenoptera: Formicidae) [PDF]
Museum of Southwestern Biology
New Mexico Spiders
Odonata Central
One Hundred Common Insects of New Mexico, NM State University [PDF]
Sanborn, A.F. and Phillips, P.K., 2013 Biogeography of the Cicadas (Hemiptera: Cicadidae) of North America, North of Mexico [PDF]
Symbiota Collections of Arthropods Network
Sutherland, C.A. Rove Beetles [PDF]
Symbiota Collections of Arthropods Network
Ticks and Tick Borne Diseases
Wildlife Notes – Centipedes and Millipedes [PDF]

Subject Area Experts (all guides)

Steve Cary (butterflies)
Beth Cortright (insects)
Terry Foxx (invasive plants)
Leslie Hansen (mammals)
Richard Hansen (fish, mammals)
Dorothy Hoard (butterflies, trees)
Chick Keller (flowers, herbarium)
Shari Kelley (geology)
Kirt Kempter (geology)
Garth Tietjen (reptiles)
David Yeamans (birds)

Web Development and Content Management

Pat Bacha
Jennifer Macke
Graham Mark
Akkana Peck


Please contact us for local nature questions and sightings. We welcome comments, corrections, and additions to our guides.

For more information about local nature, please visit our Nature Blog or subscribe to PEEC This Week.

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Showing 1 of 114 insects, spiders and kin.
Darkling Beetle

Photo: Josip Loncaric

Darkling Beetle, Desert Stink Beetle, Pinacate Beetle

(Tenebrionidae family)

Order: Coleoptera (Beetles)
Size: 0.4 - 1.4 in (10 - 36 mm)
Distinguishing Features: will raise their rear end when approached. Their bodies are oval or oblong in shape and either black or dark brown in color; body surface may be smooth or rough; have wings but do not use them

Status: native; common
Habitat: dry more desert-like areas; active year round and can be seen walking great distances to find food, appearing to wander randomly

When alarmed they stand on their heads by bending their front legs down and extending their rear legs. Depending upon the species, they produce a musty secretion that spreads over posterior parts of the body or it can be ejected as a spray. The spray, which is not easily washed off, is not painful unless you get it in your eyes or mouth. The most common species in the area is Eleodes obscurus.

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