Meloids are perhaps the most widespread and diverse coleopteran bee parasites. All known triungulin larvae develop in the nests of bees. Adults often feed on leaves and flowers; the larvae feed on nectar and pollen, and most do so in the nests of bees. Triangulin larvae, attaches to a foraging bee on the hairs, legs, or antennae and are subsequently transported back to the bee's nest. Alternatively, adult female meloids locate the open nest of a bee and then deposit eggs near the burrow. Within the bee nest, the beetle larva molts through a series of successively more grub-like and sedentary larvae, as it feeds on pollen stores.The resemblance between meloid larvae and those of bees helps to explain the fact that they are even fed by honeybee workers while in the nest.

I know the large meloid Cissites maculata  parasite in the nests of the largest carpenter bees, Xylocopa violacea . The slow moving adult beetles remain outside the xylocopine nests where the females mates and oviposits close to the nest entrance, leaving the triungulin larva to locate its host.  In India you have Cissites testaceous but you need to check.

Maybe triungulins (young larvae of Meloidae)? But I'm not sure...

I agree with Pavel (but there are some other parasitic Coleoptera families like Ripiphoridae that have similar biology and larvae so you might have to check to be sure).

I agree with Pavel. Meloidae larvae.

Meloids are perhaps the most widespread and diverse coleopteran bee parasites. All known triungulin larvae develop in the nests of bees. Adults often feed on leaves and flowers; the larvae feed on nectar and pollen, and most do so in the nests of bees. Triangulin larvae, attaches to a foraging bee on the hairs, legs, or antennae and are subsequently transported back to the bee's nest. Alternatively, adult female meloids locate the open nest of a bee and then deposit eggs near the burrow. Within the bee nest, the beetle larva molts through a series of successively more grub-like and sedentary larvae, as it feeds on pollen stores.The resemblance between meloid larvae and those of bees helps to explain the fact that they are even fed by honeybee workers while in the nest.

I know the large meloid Cissites maculata  parasite in the nests of the largest carpenter bees, Xylocopa violacea . The slow moving adult beetles remain outside the xylocopine nests where the females mates and oviposits close to the nest entrance, leaving the triungulin larva to locate its host.  In India you have Cissites testaceous but you need to check.

Thank you very much, Pavel Ozerski, Vincent Lefebvre and Serban Proches for their guidance for identification. And I also thanx to Luis .. becouse he elaborated in detail about it. Thank you all. 

Hi,

Can I just recommend the iSpot website, if you which to identify specimens?

Here is the link: http://www.ispotnature.org/communities/global

Best. Vincent

My colleage Dr. Valladares and I (J.M. Nieto) Ùniversity of León, Spain, agree with the views expressed. We think it is a trinugulin larva of a meloidean.

High Sir:

For better identification you must follow their cycle until adults. Keep also samples of pupae.

Best wishes

Marcelo 

 if you which to identify specimens? Use this

Here is the link: http://www.ispotnature.org/communities/global

More search

http://www.insectidentification.org/

They definitely look like meloid triungulins (first instar larvae) to me. There are several references such as:

McSwain, J. (1956). "A classification of the first instat larvae of the Meloidae (Coleoptera)." University of California Publications in Entomology 12: 5.

These covers North American species.

Bologna, M. A.,Turco, F., and Pinto, J. (2013). "The Meloidae (Coleoptera) of Australasia: a generic review, descriptions of new taxa, and a challenge to the current definition of subfamilies posed by exceptional variation in male genitalia." Invertebrate Systematics 27: 391–427.

Marco Bologna (Italy) and John Pinto (California, USA) are two world experts on the family Meloidae. Perhaps if you have specimens and locality data you can ship some to one of them for identification.

Best regards,

Leslie

@ Leslie

Thank you for good suggestions and info about Marco Bologna and John Pinto. I will try with the existing references.

I do have sample of triungulins only. I do not have samples of adults/matures. Does it work in identification?

They definitely are meloid triungulins (Coleoptera: Meloidae), and it is possible identified the species by the larvae, unless the case of an unknown species.

Nice specimens!  Treasure them!

I agree with the above commentaries of good specialists of Meloidae. It is sure that you can describe de triungulin that you observed within nest of Xylocopa violacea. More descriptions of larval stages of Meloidae are needed for bio-conservation in Europe. I do'nt know the country where you observed this larval ectoparasitoid of  the bumblebee. My field of observation (not of fundamental research) in the field is South-Eastern France where Xylocopa violacea lacks of flowers, when finishing the spring flowering season (after end of May or early June) and till to second flowering season (beginning between 15 August and early October, following intensity of dry summer in South-East France).