rhubarb curculio

(Lixus concavus)

Conservation Status
rhubarb curculio
Photo by Alfredo Colon
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Rhubarb curculio is a large, easily identified, true weevil. It is common from New Hampshire south to North Carolina, and west to Utah. It is uncommon in the upper Midwest, including Minnesota. The body is elongated, cylindrical, smooth, and black. At to in length and 3 16 in width, it is one of the largest snout beetles in the United States.

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.

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 the mesothorax, the third thoracic segment (metathorax), and completely cover the abdomen. They are wider than the pronotum, oblong egg-shaped, narrowed toward the tips, moderately convex, longitudinally grooved, and pitted. There is a deep depression on the elytra and pronotum where they meet.

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, as long as the prothorax. It is projected forward and slightly bent downward. The antennae are short, slender, and elbowed. The last 3 segments are expanded and form a club. There are seven jointed segments between the base and the club. The first two segments are long, the second much longer than the first. The third through seventh segments are short. On the male the antennae are inserted one-fourth of the way from the tip of the snout. On the female they are longer and are inserted one-third of the way from the tip.

The head, pronotum, and elytra are more or less dusted with a bright yellowish bloom. The bloom wears away easily, especially when the insect is handled.

The third leg segment (femur) has a pale ring-like band and is armed with a small tooth on the inner side. The fourth leg segment (tibia) has a small hook on the inner side near the tip.

 
     
 

Size

 
 

Total Length: to

 
     
 

Similar Species

 
  Dock curculio (Lixus mucidus) is the only other weevil known to attack rhubarb. It is very similar but the bloom is whitish, not yellowish, and the depression on the pronotum and elytra is not as deep.  
     
 
Habitat
 
 

Mesic habitats

 
     
 
Biology
 
 

Season

 
 

One generation per year: Mid-May to September

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

Overwintering adults become active in mid-May. After mating, the female punctures the stem or crown of a host plant with her snout and feeds, creating a cavity. She then inserts a single egg about deep into the cavity. The egg hatches in 7 to 10 days. Several eggs may be laid in a single plant but only a single larva develops to maturity, suggesting that the larvae are cannibalistic. Up to 500 or more eggs may be laid in a season by a single female. Eggs laid in rhubarb do not hatch. The larva burrows down the stalk to the ground, chews an exit hole, and pupates within the stem after about 9 weeks. Adults emerge a few weeks later, in August and September. They overwinter in leaf litter.

 
     
 

Larva Food

 
 

Stalks of all of the adult’s host plants except rhubarb.

 
     
 

Adult Food

 
 

Stalks and leaves of thistle (Carduus and Cirsium), sunflower (Helianthus), dock (Rumex), and rhubarb (Rheum).

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 27, 29, 30.

 
  7/18/2018      
         
 

Occurrence

 
 

Uncommon in Minnesota

 
         
 
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

Lixinae  
 

Tribe

Cleonini  
 

Genus

Lixus  
       
 

The tribe Cleonini is the largest tribe in the subfamily Lixinae. In the past it was sometimes treated as the separate subfamily Cleoninae.

 
       
 

Synonyms

 
 

Lixus coloradensis

Lixus crassulus

Lixus rectus

Lixus soror

 
       
 

Common Names

 
 

rhubarb curculio

rhubarb weevil

 
       
 

Curculio was the Latin name of the genus for all weevils in the 18th century. That genus now includes only nut weevils. The name has been adopted for common usage and is now another name for weevil.

 
       

 

 

 

 

 

 

 

 

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.

 

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.

 

Tibia

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

 

 

 

 

 

 
 
Visitor Photos
 
           
 

Share your photo of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more photos and, if you like, a caption.
 
 

Alfredo Colon

 
    rhubarb curculio      
           
 
MinnesotaSeasons.com Photos
 
 

 

 
           
           

 

Camera

     
 
Slideshows
 
 
     
     
     

 

slideshow

       
 
Visitor Videos
 
       
 

Share your video of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach a video, a YouTube link, or a cloud storage link.
 
 

 

 
     
     
       
       
       
 
Other Videos
 
     
     
     
       

 

Camcorder

 
 
Visitor Sightings
 
           
 

Report a sighting of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.
 
  Alfredo Colon
6/8/2018

Location: Woodbury, MN

rhubarb curculio  
           
 
MinnesotaSeasons.com Sightings
 
 

 

 

 

 

Binoculars


Last Updated:

About Us | Privacy Policy | Contact Us | © 2021 MinnesotaSeasons.com. All rights reserved.