cocklebur weevil

(Rhodobaenus quinquepunctatus)

               
Conservation Status

IUCN Red List

not yet assessed

cocklebur weevil

NatureServe

NNR - Unranked

Minnesota

not listed

Occurrence

Widespread in eastern the United States

Flight/Season

 

Habitat

 

Size

Total Length: 3 16 to 5 16

          Photo by Alfredo Colon

Identification

This is a medium-sized true weevil. It is widespread in the eastern half of the United States. The body is 3 16 to 5 16 long, elongated, and oval, more-or-less football-shaped.

The thorax is composed of three segments. The first segment (prothorax) is large and prominent and appears to be the entire thorax. It is covered by a saddle-shaped plate (pronotum). The pronotum is slightly wider than long and is rounded at the sides. The pronotum is reddish-orange with five black spots: a single, oval, median spot; and two smaller spots on each side.

There are two pairs of wings, a membranous inner pair and a hardened outer pair (elytra). The elytra are attached to the second thoracic segment (mesothorax). They cover almost but not quite all of the abdomen. They are wider than the pronotum, oblong egg-shaped, rounded at the tips, moderately convex, longitudinally grooved, and pitted. They are reddish-orange and each has five black spots. The median line where the elytra meet (elytral suture) is black. A large spot at the tip coalesces with one on the opposite elytra forming a single large spot. A smaller spot halfway between the base and the tip usually coalesces with one on the opposite elytra. A single lateral spot near the tip sometimes coalesces with the one at the tip. Two smaller lateral spots near the base are always separated. Rarely, almost the entire elytra will be black.

The head is greatly elongated between the eyes and the mouth parts forming a conspicuous snout. The snout is narrow, enlarged toward the tip, and very long, about as long as the prothorax. It is projected forward and bent downward. The antennae are short, slender, and elbowed. They have eleven segments. The last 3 segments are expanded and form a club. The antennae are inserted near the eyes.

The legs are black. The last part of each leg (tarsus), corresponding to the foot, has five segments. The fourth segment is very short and is concealed within the broadened tip of the third segment, making the tarsus appear to have only four segments.

 
Similar
Species

Ironweed curculio (Rhodobaenus tredecimpunctatus) is larger, up to 7 16 long. The median line where the elytra meet (elytral suture) is red. The black spots on the elytra are always separated. They do not coalesce to form patches.


Larval Food

Stalks of all of the adult’s host plants

 
Adult Food

Stalks and leaves of cocklebur (Xanthium), ragweed (Ambrosia), thistle (Carduum), ironweed (Vernonia), Joe Pye weed (Eutrochium), sunflower (Helianthus), marsh elder (Iva), and rosinweed (Silphium).

 
Life Cycle

 

 
Behavior

Larvae bore into the stems or roots of cocklebur and ragweed.


Distribution Distribution Map  

Sources: 24, 29, 30.


Comments

 


Taxonomy

Order:

Coleoptera (beetles)

 

Suborder:

Polyphaga (water, rove, scarab, long-horned, leaf and snout beetles)

 

Infraorder:

Cucujiformia

 

Superfamily:

Curculionoidea (snout and bark beetles)

 

Family:

Curculionidae (snout beetles, weevils)

 

Subfamily:

Dryophthorinae (palm weevils)

 

Tribe:

Rhynchophorini

 

Subtribe:

Sphenophorina

 
Synonyms

Rhodobaenus formosus

Rhodobaenus triangularis

 
Common
Names

cocklebur weevil


 

 

 

 

 

 

Glossary

Elytra

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

 

Pronotum

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

 

Prothorax

The first (forward) segment of the thorax on an insect, bearing the first pair of legs but not wings.

 

Tarsus

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

 

 

 

 

 

       

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Alfredo Colon


Weevil

From Woodbury, MN. Taken on June 8, 2018.

  cocklebur weevil    

       
       
       

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Other Videos

 
  Cocklebur Weevil (Rhodobaenus quinquepunctatus) - On A Mission
Nature's Wild Things
 
   
 
About

Published on Jun 7, 2017

Cocklebur Weevil (Rhodobaenus quinquepunctatus) On A Mission
Video 30 sec long 14% Speed - Audio none Cabarrus County, North Carolina, United States Photo Walk - 06-7-2017

 
     
  Attack of the Killer Weevils!! What the damage looks like on sunflowers and how to kill them.
Midwest Gardener
 
   
 
About

Published on Jun 10, 2016

It seems like every year I run into a bug or two that I've never dealt with before. This year, it is a little red/orange weevil with black spots. The best I can tell, it is either a cocklebur weevil, or the ironweed curculio. They can really do damage to sunflowers. At first I thought that some broken leaves were due to some high winds that we had been having, but soon figured out it was the weevils.

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Alfredo Colon
6/8/2018

Location: Woodbury, MN

cocklebur weevil


     
     
 

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