thistle tortoise beetle

(Cassida rubiginosa)

Conservation Status
thistle tortoise beetle
Photo by Alfredo Colon
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Thistle tortoise beetle is native to Europe and Asia. It was introduced into Quebec in 1901 and has since spread across the continent. It is now common in the northern United States from Vermont south to Maryland and west to Great Lakes states, present but uncommon in the west. It is uncommon in Minnesota but probably increasing. It was introduced into New Zealand as a control of the non-native Canada thistle. Though effective, it is not used in the United States because it also attacks beneficial native thistles.

Adults are tortoise-shaped, ¼ to 5 16 (6 to 8 mm) long, oval when viewed from above, and convex when viewed from the side. The female is larger than the male.

The upper thoracic plate (pronotum) and hardened wing covers (elytra) are green. The edges are spread out, flattened, and thin, and extend over the head and legs. The front (anterior) edge of the pronotum is broadly rounded. The corners at the base of the pronotum are at right angles. The plate between the wing bases (scutellum) is small and triangular. The front margins of the elytra, when taken together, form a very shallow arc with a strong, brace-like excavation around the scutellum. The upper surface of the elytra is covered with small punctures but is not deeply pitted or wrinkled. There is a small depression on each elytron in the middle on the front margin. Each depression usually contains a small spot or dark shading. The inner margin of each elytron, where they meet (together called the suture) often has dark shading. The underside of the body is black.

The head is completely concealed when viewed from above. The eyes are not notched. The antennae are long but less than half as long as the body. The first five segments are pale, the remainder dark. Segment 3 is distinctly longer than segment 2, and segment 8 is distinctly longer than wide. The antennae are extended when at rest. There is no groove on the underside of the prothorax for them to be tucked into.

The third segment of the leg (femur) is black at the base, orangish-brown at the tip. The fourth segment (tibia), and the last part of leg (tarsus), corresponding to the foot, are orangish-brown. The tarsus 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. The last segment bears a pair of well-developed claws.

 
     
 

Size

 
 

Total Length: ¼ to 5 16

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Weedy fields, roadsides, parks

 
     
 
Biology
 
 

Season

 
 

One generation per year: March through September

 
     
 

Behavior

 
 

Adults feed on the underside of leaves, larvae feed on the upperside. They eat round holes in the leaves.

The larvae carry dried fecal matter over their body, presumably as a form of camouflage. The fecal matter is attached to a forked appendage on the last abdominal segment, and is held suspended over the body.

 
     
 

Life Cycle

 
 

Adults overwinter in tussocks, leaf litter, and moss. The female lays groups of eggs on the underside of leaves near the base of the plant. The eggs hatch in about a week, and the young reach maturity in about six weeks.

 
     
 

Larva Food

 
 

 

 
     
 

Adult Food

 
 

Leaves of plants in the Asteraceae (Aster) family, especially thistles Carduus, Cirsium, and Onopordum, but also knapweed and burdock.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 27, 29, 30.

 
  1/12/2019      
         
 

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

Chrysomelidae (leaf beetles)  
 

Subfamily

Cassidinae (tortoise beetles and the hispines)  
 

Tribe

Cassidini (tortoise beetles)  
  Genus Cassida  
 

Subgenus

Cassida  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

green thistle beetle

thistle tortoise 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.

 

Pronotum

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

 

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.

 

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).

 

 

 

 

 

       
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Alfredo Colon
       
  thistle tortoise beetle   thistle tortoise beetle
       
  thistle tortoise beetle    
       
MinnesotaSeasons.com Photos
   
       
       
       

 

Camera

     
Slideshows
   
  2.1. Thistle Tortoise Beetle (Cassida rubiginosa)
Bill Keim
 
  2.1. Thistle Tortoise Beetle (Cassida rubiginosa)  
     
  Thistle Tortoise Beetle (Cassida rubiginosa)
Andree Reno Sanborn
 
  Thistle Tortoise Beetle (Cassida rubiginosa)  

 

slideshow

       
Visitor Videos
       

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Other Videos
 
  Thistle Tortoise Beetle (Chrysomelidae: Cassida rubiginosa) on Leaf
Carl Barrentine
 
   
 
About

Published on Jun 5, 2010

Photographed at Grand Forks, North Dakota (04 June 2010).

   
       
  Cassida rubiginosa
Aglaia Bouma
 
   
 
About

Published on Jul 16, 2017

Short little movie about the way the Thistle Tortoise Beetle moves around, how it looks underneath its "shell" and how it eats.

   
       
  Cassida Rubiginosa
Macro Nature
 
   
 
About

Published on Apr 3, 2017

   
       
  LITTLE GREEN BUG[CASSIDA RUBIGINOSA]
MrElephant47
 
   
 
About

Published on Aug 2, 2011

THIS LITTLE GREEN BUG IS KNOWN AS [CASSIDA RUBIGINOSA]WILL I THINK THAT'S WHAT IT'S CALLED???COULD BE WRONG SOME ONE LET ME KNOW!

   
       

 

Camcorder

         
Visitor Sightings
   

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Alfredo Colon
8/20/2018

Location: Woodbury, MN

thistle tortoise beetle


Alfredo Colon
7/15/2018

Location: Woodbury, MN

thistle tortoise beetle


Alfredo Colon
7/12/2018

Location: Woodbury, MN

thistle tortoise beetle


     
     
 
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Created: 1/12/2019

Last Updated:

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