Dear Michal,

First question is which species you want to sample? What is the damage these insects cause? How about their life history, habitat and dispersion?

The first step is always to study the references available on these insects according to your aims.

Dear Andras,

thank you for your answer. I do not know what species is this as researchers usually refer to them as to Curculio spp. I think that knowing excactly what species it is is not so important (there maybe even more then one). I just would like to know the difference in abundance of Curculio on two sites to test the hypothesis that the differences in infestation of oaks acorns on those sites can be explained by differences in abundance of insects.These are Curculio that oviposit eggs in red oak acorns, then larvea hatch after the acorn drop on the ground and bury itself in the ground where it stays through the winter. In spring larvea develop into the adult and adult individual climb the tree and lay eggs in acorns. 

I am looking for people that have some experinace on "counting" weevils (Curculio) and have the good will to share it:):)

best,

Please read "The Ecology and Silviculture of Oaks" Chapter 1 page 75.

Acorn traps are mentioned there with figures.

Dear Michal,

Your insect must be acorn weevil (Curculio glandium, Curculionidae). Now , you can look for references at internet. Good sampling method can be worked out only if one knows the biology and life history of an animal.

If you do not know the biology of insects, I would recommend the simplest way of sampling: collect acorns time to time if you can. I would say collect 10 acorns per tree from multiple trees over time. I would collect acorns from the same trees over and over again. 

I do not think simple abundance measurements will give you a clear answer; you should provide how damage is linked to the abundance.

I am already doing this. Thank you anyway! :)