splendid earth-boring beetle

(Geotrupes splendidus)

Conservation Status
splendid earth-boring beetle
Photo by Luciearl
  IUCN Red List

not listed

     
  NatureServe

NR - Unranked

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Splendid earth-boring beetle is a medium-sized scarab beetle. It is one of the most common and most widely distributed species in the genus.

Adults are ½ to ¾ long and ¼ to ½ wide. The body is very stout, oval when viewed from above (dorsally) and strongly convex when viewed from the side (laterally). It is shiny and usually bright metallic green, purple, or bronze, sometimes light blue.

The first segment of the thorax is large and is covered above by a metallic green exoskeletal plate (pronotum). The pronotum is coarsely and unevenly pitted (punctate).

The hardened outer forewings (elytra) are free, not fused; ridged longitudinally (striate); and pitted in rows. The pits are shallow but well developed. The elytral margins are narrowly flared. The innermost grooves (stria), where the elytra meet in the middle, do not extend to the base of the elytra. The color of the stria is the same as the color of the rest of the elytra. There is a small, metallic green, triangular plate (scutellum) between the bases of the wings that is not covered by the elytra. The sides of the scutellum are only slightly curved.

The head is large and is not concealed beneath the pronotum. The antennae are dark reddish-brown and clubbed. They have 11 segments. When viewed from above the base of the antennae are not visible. The last three segments are light reddish-brown and are expanded sideways on one side into long flattened lobes. The antennal lobes can be closed into a tight club or fanned out to detect odors. They are small and both sides are straight, not convex.

The legs are stout and black with a slight bluish or greenish iridescence on the upper surface of the third and largest leg segment (femur). The fourth segment (tibia) of the front leg of the male is enlarged, broad, and adapted for digging. The tibia of the middle and hind legs have a distinct horizontal ridge. The end segment of each leg (tarsus) has 5 sections.

There are two recognized subspecies. G. s. miarophagus is larger, to ¾ long and to ½ wide, coppery green to purplish-black, and is found generally west of the Appalachian Mountains. G. s. splendidus is smaller, ½ to 11 16 long and ¼ to 7 16 wide, bright green or occasionally light blue,rarely purplish-black, and is found generally east of the Appalachian Mountains. They are otherwise identical in appearance.

 
     
 

Size

 
 

Total Length: ½ to ¾

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

 

 
     
 
Biology
 
 

Season

 
 

One generation: March to November

 
     
 

Behavior

 
 

Adults are active at night.

 
     
 

Life Cycle

 
 

In September and October, new male adults emerge about a week before the females. They feed mostly on fungi. During this time, the male creates a burrow 5 to 8 inches deep into the soil under decaying fungi. He provisions it with the decaying fungi, feeds in the burrow, and waits for a female. Copulation takes place inside the burrow. Before or after breeding, a 2½ to 3½ long, 1 in diameter food cell is excavated. The food cell is then tightly packed with concentric layers of pieces of dead leaves. The adult male and female overwinter in the burrow, emerging the following April. From April through June the female deposits yellowish-white eggs in the food cell. The larvae pass through three stages of development (instars) before pupating.

 
     
 

Larva Food

 
 

 

 
     
 

Adult Food

 
 

The preferred food is fungi, but adults have also been seen feeding on carrion, dung, and feathers.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 29, 30.

 
  6/21/2018      
         
 

Occurrence

 
 

Common and widespread in eastern and midwestern United States

 
         
 
Taxonomy
 
 

Order

Coleoptera (beetles)  
 

Suborder

Polyphaga (water, rove, scarab, longhorn, leaf and snout beetles)  
 

Infraorder

Scarabaeiformia  
 

Superfamily

Scarabaeoidea (scarab, stag and bess beetles)  
 

Family

Geotrupidae (earth-boring scarab beetles)  
 

Subfamily

Geotrupinae  
 

Genus

Geotrupes  
  Subgenus Geotrupes  
       
 

Almost all sources of information for this species, including BugGuide.net, refer to this species by the scientific name Geotrupes splendidus. The usually reliable ITIS, originally referred to as Interagency Taxonomic Information System, now just ITIS, lists this species as Geotrupes splendidulus. A very few other sources also use this spelling. It is not known whether this is a misspelling that got picked up by a (very) few authors, or a legitimate synonym. However, Geotrupes splendidulus is never listed as a synonym for Geotrupes splendidus.

 
       
 

Subordinate Taxa

 
 

splendid earth-boring beetle (Geotrupes splendidus miarophagus)

splendid earth-boring beetle (Geotrupes splendidus splendidus)

 
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

glossy pillbug

splendid earth-boring beetle

 
       

 

 

 

 

 

 

Glossary

Elytra

The hardened or leathery forewings on an insect used to protect the fragile hindwings, which are used for flying, in beetles and true bugs.

 

Femur

On insects and arachnids, the third, largest, most robust segment of the leg, coming immediately before the tibia. On humans, the thigh bone.

 

Instar

The developmental stage of arthropods between each molt; in insects, the developmental stage of the larvae or nymph.

 

Pronotum

The saddle-shaped, exoskeletal plate on the upper side of the first segment of the thorax of an insect.

 

Punctate

Dotted with pits (punctures), transluscent sunken glands, or colored spots of pigment.

 

Scutellum

The exoskeletal plate covering the rearward (posterior) part of the middle segment of the thorax in some insects. In Coleoptera, Hemiptera, and Homoptera, the dorsal, often triangular plate behind the pronotum and between the bases of the front wings. In Diptera, the exoskeletal plate between the abdomen and the thorax.

 

Striate

Striped or grooved in parallel lines (striae).

 

Tarsus

The last two to five sections of an insect’s leg, attached to the tibia; the foot. Plural: tarsi.

 

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot).

 

 

 

 

 

 
 
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Luciearl

 
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  Splendid Earth Boring Beetle (Geotrupes splendidus)  

 

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  Luciearl
6/14/2018

Location: Lake Shore, MN

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