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Photo#175365
Predacious Diving Beetle larva - Ilybius

Predacious Diving Beetle larva - Ilybius
Groton, Middlesex County, Massachusetts, USA
April 3, 2008
Size: 20mm

Images of this individual: tag all
Predacious Diving Beetle larva - Ilybius Predacious Diving Beetle larva - Ilybius Predacious Diving Beetle larva - Ilybius

Moved
Moved from Ilybius.

Thanks Tim

Either Ilybius or Agabus
I see 2 whorls of hair on each cercus..(characteristic of these 2 genera)
id confirmation based on arrangement of dorsal spines on the foreleg femur, absence/presence of a lateral keel on the head and positioning of lateral head spines relative to the ocelli (eyes)..sorry for not pointing that out to you earlier...this is a tough one =/

 
Closeup of head and legs added
Tim, does the blown-up picture of the head and legs give enough detail to go further?

 
Yes!
I can see the dorsal spines on the front femur. This appears to be a larva of Ilybius; the row of spines extends to the distal (outer) half of the femur (in Agabus larvae, the spines are confined to the basal half of the femur)..Thanks again!

Genus id...
requires close inspection of the cerci and last 2 abdominal segments; the presence and distribution of lateral hairs (if present; this specimen appears not to have any) and setae are some of the diagnostic characters needed to confirm id

 
Close-up image added
Hopefully this other image will help in the id.