Damselflies are frequently used as indicators of environmental health. Their aquatic larvae constitute a natural biological control over mosquito larvae and thus help to control several epidemic diseases like malaria, dengue, filaria etc. Their life history is closely linked to specific aquatic habitats making them an indicator of wetland health (Andrew et al., 2008). Saikheda water reservoir of Yavatmal district, Maharashtra (India) were studied for rainy season from June 2013 to September 2013 of two station of Saikheda dam. A total of 10 species belonging to three families of Damselfly were identified.

In certain situations of experimentation using usual blocking each experimental plot contains direct effect of the treatment applied to it together with effects of treatments percolating from its neighbouring left and right plots. This paper is concerned with the study of block designs of OS1 Series for two sided (left and right) second- order neighbour effects. Neighbour Designs can 2 be constructed using MOLS for the parameters v=s , b=s(s+1), r=s+1, k=s, ë=1 where s is either a prime number or power of a prime number. Here left and right second-order neighbours of every treatment are finding out and it is observed that these neighbours follow the property of circularity of secondorder.