weevil

(Lixus terminalis)

Conservation Status
weevil (Lixus terminalis)
Photo by Alfredo Colon
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Lixus terminalis is a medium-sized true weevil. It occurs across North America. The body is elongated, cylindrical, smooth, and 5 16 to 7 16 (8 to 11 mm) long. The overall color is walnut brown, at least in museum specimens.

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 longer than wide, has straight sides, is rounded vertically, and is depressed in the middle. It is slightly wider at the base than the wings at their base. The base is straight near the sides and has a small triangular projection (lobe) in the middle. The surface is pitted with scattered large and small punctures.

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 at the base in the middle that joins the similar depression on the pronotum. The tips of the elytra are rounded and distinctly separated. The pronotum and elytra are covered with short, fine, gray hairs. These hairs wear off irregularly, becoming patchy on older individuals.

The head is greatly elongated between the eyes and the mouth parts forming a conspicuous snout (rostrum). The rostrum is relatively thickened, enlarged toward the tip, and very long, as long as the prothorax. It is projected forward and slightly bent downward. Antennae are inserted one fifth of the way from the tip. 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. The first antennal segment (joint) beyond the base is thicker than the second joint. The second joint is as long or longer than the next two joints combined.

The third leg segment (femur) is slightly club-shaped.

 
     
 

Size

 
 

Total Length: 5 16 to 7 16

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

 

 
     
 
Biology
 
 

Season

 
 

One generation per year: April through August

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

Overwintering adults become active in April. 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. The larva burrows into the stalk or roots creating a gallery and pupates within the gallery. Adults overwinter in leaf litter.

 
     
 

Larva Food

 
 

Host plant stalks.

Larvae have been reared on the laboratory on water smartweed and Pennsylvania smartweed. What the hosts are in nature is unknown.

 
     
 

Adult Food

 
 

Host plant soft tissues

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 27, 29, 30.

 
  12/19/2018      
         
 

Occurrence

 
 

 

 
         
 
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  
       
 

Synonyms

 
 

Lixus blakeae

 
       
 

Common Names

 
 

This species has no common name. One of the common names of the family Curculionidae is weevils, and is applied here for convenience.

 
       

 

 

 

 

 

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.

 

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.

 

Rostrum

The stiff, beak-like projection of the carapace or prolongation of the head of an insect, crustacean, or cetacean.

 

 

 

 

 

 
 
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Alfredo Colon

 
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  Alfredo Colon
6/21/2018

Location: Woodbury, MN

weevil (Lixus terminalis)  
           
 
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Created: 12/19/2018

Last Updated:

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