silver flower longhorn beetle

(Grammoptera subargentata)

Conservation Status
silver flower longhorn beetle
Photo by Alfredo Colon
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Silver flower longhorn beetle is small to moderate sized, flower longhorn beetle. It occurs across North America from southern Quebec to Alaska south to North Carolina and California. It is most common west of the Great Plains. Based on the number of reported observations, it is uncommon in Minnesota. However, Cedar Creek Ecosystem Science Reserve (CCESR) in Anoka County reports it as common. It is found in spring and summer on flowers in deciduous and mixed woodlands. Larva feed on dead hardwoods, including sumac, poplar, and, oak. Adults feed on flower pollen from a wide variety of flowers including at least thirteen genera.

Adults are 3 16to 5 16 (5 to 8 mm) long. The body is robust, broad-shouldered, cylindrical, and almost parallel. Females are slightly larger than males.

The head is black, short in front, inflated behind the eyes, and abruptly constricted in back forming a neck that is visible when viewed from above. The upper part (vertex) is very densely covered with very fine pits. The face slants forward or is nearly vertical. The compound eyes are small, black, and slightly notched. The antennae have eleven segments. They are slender, black, and long, almost as long as the body. The base of each antenna is narrowly separated from the base of the jaw (mandible), and is not surrounded by the compound eye. The second antennal segment is short. All of the segments are cylindrical and are longer than wide. The finger-like sensory organ (maxillary palp) attached to the mouth is blunt at the tip, not pointed.

The upper thoracic shield (pronotum) is black, bell-shaped, and wider than long. It is narrow at the front and almost as wide at the base as the base of the hardened wing covers (elytra). It is moderately inflated on top (dorsally). It has a very shallow impression in the middle near the base. The angles at the rear corners of the pronotum are very sharp and point outward. The surface of the pronotum is very densely covered with very fine pits, and is also covered with short, curved, silvery hairs. This is the feature that gives the beetle its common name. On some individuals the hairs are dark but they are never golden.

The elytra are entirely black, shiny, and elongated, usually less than 2½ times as long as the base is wide. They are broadest at the base and almost parallel from below the base to the rounded tip. The elytral surface is pitted, finely on the basal half, even finer on the rear (apical) half. It is also moderately covered with short dark hairs. The abdomen has five visible segments on the underside. On the female the last segment is rounded at the end and does not have a bump (tubercle).

The legs are long, slender, entirely black, and covered with short hairs and fine pits. The fourth segment (tibia) of each leg has two short spurs at the tip. The last part (tarsus), corresponding to the foot, is black. The tarsus has five segments but the fourth segment is minute and is concealed within the lobes of the heart-shaped third segment, making it appear that there are only four segments. On the hind leg, the tarsi are slender. The third segment is split beyond the middle.

The bases of the antennae, the plate on the face above the upper lip (clypeus), and the legs are sometimes partly reddish.

 
     
 

Size

 
 

316 to 516 (5.0 to 8.0 mm)

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Deciduous and mixed woodlands

 
     
 
Biology
 
 

Season

 
 

April to August

May and June (CCESR)

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

 

 
     
 

Larva Food

 
 

Dead hardwoods

 
     
 

Adult Food

 
 

Pollen from a wide variety of flowers including at least thirteen genera.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 27, 29, 30, 82.

 
  8/17/2021      
         
 

Occurrence

 
 

Uncommon in Minnesota

 
         
 
Taxonomy
 
 

Order

Coleoptera (beetles)  
 

Suborder

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

Infraorder

Cucujiformia  
 

Superfamily

Chrysomeloidea (long-horned and leaf beetles)  
 

Family

Cerambycidae (long-horned beetles)  
 

Subfamily

Lepturinae (flower long-horned beetles)  
 

Tribe

Lepturini  
 

Genus

Grammoptera  
       
 

Synonyms

 
 

Grammoptera filicornis

Grammoptera quebecensis

Grammoptera rufibasis

Grammoptera similis

 
       
 

Common Names

 
 

silver flower longhorn beetle

 
       

 

 

 

 

 

Glossary

Clypeus

On insects, a hardened plate on the face above the upper lip (labrum).

 

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. Singular: elytron.

 

Maxillae

Paired mouth structures of arthropods located immediately behind the mandible and used for tasting and manipulating food. “Under-jaws”.

 

Palp

Short for pedipalp. A segmented, finger-like process of an arthropod; one is attached to each maxilla and two are attached to the labium. They function as sense organs in spiders and insects, and as weapons in scorpions. Plural: palpi or palps.

 

Pronotum

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

 

Tarsus

The last two to five subdivisions 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). The fifth segment of a spider leg or palp.

 

Tubercle

On plants and animals: a small, rounded, raised projection on the surface. On slugs: raised areas of skin between grooves covering the body.

 

Vertex

The upper surface of an insect’s head.

 

 

 

 

 

 
 
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Alfredo Colon

 
    silver flower longhorn beetle      
           
 
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  Alfredo Colon
6/8/2018

Location: Slinger, Wisconsin

silver flower longhorn beetle

 
           
 
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Created: 8/17/2021

Last Updated:

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