An indication on the size (length) of the specimens would be helpful.  On the basis of the second and particularly the fifth photo, these specimens seem to be apod larvae of holometabolous insects. The silhouette of the larva in the fifth photo recalls certain leaf-miner beetles of the family Buprestidae (cf. genus Trachys).  Alternatively, they could perhaps be apod larvae of Diptera, or Hymenoptera. In the third photo a cocoon, in the fourth photo another protection seems to be present. More detailed information and photos at higher magnification are needed for a surer answer. We should see better the cephalic sclerotized structures and particularly the mouthparts. Regards,

Rinaldo Nicoli

an insect larva, it seems wit no doubt

it is a larva witout legs, hence unusual for coleoptera, but usual for curculionidae

the only additional element useful for identification is the aquatic life, wic could address towards other insect orders with larvae without legs (diptera?). the aquatic lifestyle, infact, is not typical of curculionidae larvae.

Dears Rinaldo and Genuario,

thanks for your answers.

The specimens are about 3mm of lengh and I am pretty sure that they don't belong to any group of Diptera.

The subfamily Bagoinae (Curculionidae) has aquatic larvae, but they don't seem to belong to this group.

Do you know if genus Trachys has also aquatic larvae?

Attached you can find some more pictures at higher magnification.

Thank you again for your help.

Regards

Matteo

But are these larvae found dead or alive in the water? They may also be larvae which fall accidentally into the water, for example from the branches of a tree above. The  photos at higher magnification show clearly that these are larvae with eucephalic head capsule. This fact permits to exclude a lot of families of Diptera. The general shape also resembles that of the larvae of certain leaf-miner Lepidoptera. Furthermore, the first photo of the second series suggests a larva with strongly developed silk glands (labial silk glands). My hypothesis now is that they are larvae of leaf-miner Lepidoptera (there are groups with hypermetabolic development and two larval types, and leaf miners have often morphologically specialized larvae, e.g. also in some Lepidoptera we can find apod or almost apod larvae in leaf miners). The fall into water (instead of on the ground) in this hypothesis can be occasional. Unfortunately I have no time now to compare these photos with the morphology of the various types of leaf-miner Lepidoptera larvae. Such a research could be useful. As regards leaf-miner Buprestidae such as Trachys, the larvae don't live in the water, obviously. Regards,

Rinaldo Nicoli

Trichoptera?

It could be a larva of one of the genera of Curculionidae.Please find the attached web site to identify it

Regards

http://www.ukflymines.co.uk/Images/gallery/Larvae/non-Diptera/Coleoptera.php

The answer by Wafaa Osman orients, in my opinion, to the right way. It could be like that the larvae in the photos are weevil larvae, maybe of Orchestes  (or Rhynchaenus), characteristic jumper weevils  with leaf-miner larvae (also in willows near water bodies, for example). From the beginning of this question, looking at the first photos, I had the impression that the larval shape recalled leaf-miner larvae of Coleoptera, or Lepidoptera (rather different from leaf-miner larvae of Diptera, and also from leaf-miner Hymenoptera (Tenthredinidae)). My late Master Prof. Giorgio Domenichini once told me that hardly equal morphological adaptations correspond to different functions, so the very characteristic shape of the thoracic and abdominal segments of the larvae in the photos suggested the convergence to this lifestyle, the mining leaves. Even these weevil larvae build cocoons to pupate, so the presence of strongly developed labial glands is justified. It remains to understand why they are found in the water, I think it is for an accidental fall. Regards,

Rinaldo Nicoli