oil beetle

(Meloe impressus)

               
Conservation Status

IUCN Red List

not yet assessed

oil beetle (impressus)

NatureServe

NNR - Unranked

Minnesota

not listed

Occurrence

Infrequent

Flight/Season

August to October

Habitat

 

Size

Total Length: ½ to 1


Identification

This is an elongated, medium-sized, blister beetle, ½ to 1 in length. Males are smaller than females.

The head, body, and legs are usually brilliant metallic blue, violet, or green, sometimes black.

The head is more or less rectangular when viewed from above. It is 70% to 80% as long as wide and is abruptly constricted behind the eyes forming a short neck. It is sparsely covered with scattered, fine pits. The upper margin of the eye is nearly straight. The antennae are bead-like and have 11 rounded segments. On males, the antennae are bent in the middle with segments 5, 6, and 7 forming a C-shaped kink. Segment 5 is enlarged and flared outward at the end.

The thorax is narrower than the head and abdomen. The upper plate covering the thorax (pronotum) has straight sides that converge toward the rear (posteriorly). It is sparsely covered with scattered, fine pits.

The abdomen is oval-shaped. There are no hindwings. The hardened forewings (elytra) are small, much shorter than the abdomen, and overlap at the base.

The legs are long and slender. The femur of the front leg does not have a patch of hair. A outer spur at the end of the fourth leg segment (tibia) of the hind leg projects toward the rear.

 
Similar
Species

 


Larval Food

Bee eggs and stored food in ground-nesting bee nests.

 
Adult Food

Plant foliage and flowers of many plants, including field mustard (Brassica rapa), hepatica (Anemone acutiloba or A. americana), spotted touch-me-not (Impatiens capensis), tall buttercup (Ranunculus acris), bristly buttercup (Ranunculus hispidus), Irish potato (Solanum tuberosum), virgin’s bower (Clematis spp.), and eastern white pine (Pinus strobus).

 
Life Cycle

The female deposits eggs on foliage or in a 1″ deep burrow in the ground. After the eggs hatch the larvae pass through four stages. The first stage (triungulin) is mobile on plants. The entire hatched group climbs to the top of a plant and forms a cluster in roughly the shape of a female ground bee. It then exudes a chemical scent that mimics the pheromone of a female bee. When a male bee attempts to mate with the mass, some of the larvae attach themselves to its hairs. When the male mates with a female bee some of the larvae attach to the female. These remain on the female while she builds a nest, then detach and begin feeding on newly laid bee eggs. The second stage of this larva is a short-legged grub, called “first grub”, that spans four molts (instars). This stage feeds on honey in the nest. The third stage/sixth instar, called coarctate, is legless and immobile. The larva usually overwinters in this stage is a state of low metabolic activity (diapause), though it may overwinter in other stages. The fourth stage/seventh instar, called “second grub”, is a nonfeeding form that resembles the first grub. This stage feeds on honey and stored pollen. it is soon followed by the pupal stage.

Favorable environmental conditions may cause the larva to skip the coarctate stage. Adverse conditions may cause it to molt from the second grub back to the first grub, delaying the pupal stage until conditions improve.

 
Behavior

They are found on the ground or on low foliage.


Distribution Distribution Map  

Sources: 7, 24, 29, 30.


Comments

Do Not Touch!
When threatened or mishandled blister beetles (family Meloidae) exude a yellowish liquid from their joints. The thick oily substance contains the toxin cantharidin, which causes blistering on human skin.


Taxonomy

Order:

Coleoptera (beetles)

 

Suborder:

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

 

Infraorder:

Cucujiformia

 

Superfamily:

Tenebrionoidea

 

Family:

Meloidae (blister beetles)

 

Subfamily:

Meloinae

 

Tribe:

Meloini

 
Synonyms

 

 
Common
Names

impressive meloine beetle

oil beetle


 

 

 

 

Glossary

diapause

A period of decreased metabolic activity and suspended development.

 

elytra

The hardened 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.

 

instar

The developmental stage of arthropods between each molt; in insects, the developmental stage of the larvae or nymph.

 

pronotum

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

 

tibia

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

 

 

 

 

 

       

Visitor Photos

   
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L


  oil beetle (impressus)   oil beetle (impressus)

Michael Tuma


  oil beetle (impressus)    

Mary Beth Townley


  oil beetle (impressus)    

       
       
       

MinnesotaSeasons.com Photos

   

Male

  oil beetle (impressus)   oil beetle (impressus)
       
  oil beetle (impressus)    
       

Male and Female

  oil beetle (impressus)   oil beetle (impressus)
       
       

 

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slideshow

     

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Other Videos

 
  Wild Life Skills #9 - Oil beetles
Welcome to Wildlife Watch!
 
   
 
About

Uploaded on May 3, 2011

Nick Baker gets up close to one of the UK's most incredible insects - the oil beetle. Big, black and shiny with an amazing lifecycle, Nick's film will help you to discover more about these unusual animals plus you can find out more onour website: www.wildlifewatch.org.uk/oil-beetles

 
     
  Published on Feb 7, 2015
Animal Planet
 
   
 
About

Published on Feb 7, 2015

The blister beetle genus Meloe is a large, widespread group commonly referred to as oil beetles. They are known as "oil beetles" because they release oily droplets of hemolymph from their joints when disturbed; this contains cantharidin, a poisonous chemical causing blistering of the skin and painful swelling. Members of this genus are typically flightless, without functional wings, and shortened elytra.

As in other members of the family, they are hypermetamorphic, going through several larval stages, the first of which is typically a mobile triungulin that finds and attaches to a host in order to gain access to the host's offspring. In this genus, the host is a bee, and each species of Meloe may attack only a single species or genus of bees; while sometimes considered parasitoids, it appears that in general, the Meloe larva consumes the bee larva along with its provisions, and can often survive on the provisions alone, thus they do not truly qualify .

 
     
  Awesome Detailed Macro Video Of An Oil Beetle On My Hand
Samantha Wimblett
 
   
 
About

Published on Mar 21, 2014

We have Oil Beetles in our Wiltshire Garden. Oil Beetles are reliant on solitary bees for their survival. Due to the destruction of the countryside ( by many different factors ) there has been a decline in the solitary bees. Thus the oil beetles are now declining rapidly.

TAKE CARE OF THEM, OIL BEETLES ARE LISTED AS PRIORITY SPECIES FOR CONSERVATION.

Video & Music by Samantha Wimblett

Pictures & Video using a Lumix FZ200 bridge camera

 
     

 

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Visitor Sightings

   
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L
9/2/2017

Location: Big Lake, Sherburne County

oil beetle


Michael Tuma
8/15/2017

Location: Miesville Ravine Park Reserve, Miesville, MN

oil beetle


     
     
 

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