1. INTRODUCTION
Biodiversity is the living wealth of earth and is the quintessence of life. Diversity takes into consideration how individuals are distributed amongst the species (Wolda, 1988; Guo et al ., 2013; Beck et al ., 2017; Kemp et al ., 2017). India is second most populous country in the world not just in terms of humans but also stands among the top countries with worlds’ rich biological diversity. The Northern hilly region of India is exceptional for its diverse floral and faunal constitution. Himachal Pradesh (Fig I a ) with a geographical area of 55673 Km2 is a hill state of India (30.38°- 33.21° North latitudes and 75.77°-79.07° East longitudes) comprising 12 districts (Statistical Data, 2010). Divided in to four agro-climatic zones with altitudinal range from 350 to 7000 meters above mean sea level (Fig I a &b) and ecosystems temperature from 0° to more than 40° Celsius, the transforming region has low altitude evergreen forests, subtropical fruit trees, lustrous greens and agriculture crops to conifers and vegetables in mid and higher attitudes to smaller shrubs temperate fruits (Singh, 2007) and very few vegetation at extreme altitudes dry temperate zones (CES Technical Report, 2013). The congenial atmospheric conditions favour the luxuriant growth of various plant and animal species as well as support the largest phylum of arthropods. Insects are one of the most significant sections of the biological diversity of any region. These organisms can endure even the acute and harshest of environmental conditions due to their expansive ability of adaptation to wider range of climate (Sala et al ., 2000; Beck et al ., 2010; Lefebvre et al ., 2018; Plantet al ., 2018). Therefore, research on the various subjects of their behaviour, environmental impact, survey, geographical distribution and records, etc. constitute very crucial role in any study useful for understanding their diversity alteration and conservation (Mccain, 2005; Watkins et al ., 2006; Bässler et al ., 2009; Moscol Olivera & Cleef , 2009; Desalegn &Beierkuhnlein, 2010; Jaramillo-Villaet al ., 2010; Shimono et al ., 2010; Nagaike, 2010).
In view of this, despite being one of the most diverse habitats of India several insect families remain poorly studied in the state. Cicadellidae, one of the largest insect families of order Hemiptera distributed worldwide is one among them, containing at least 20,000 described species (Nielson, 1985). These tiny hemimetabolous insects are generally herbivores that suck sap from the plants, trees, shrubs and grasses etc feeding on wide range of plant fauna. Looking at agricultural aspect, these minute insects cause harmful economical damage to crops either by sucking the sap and making the plant extremely weak or indirectly by transmitting pathogenic viruses and phytoplasmas from plant to plant, which is most difficult to manage and of major serious concern (Nielson, 1968; Klein, 2001; Redak et al ., 2004; Weintraub and Beanland, 2006).
Being one of the megadiverse taxon with enormous species richness and distributional limits of such a group of insects that have high economic impact and might be undergoing species drift, extinction or mutation due to rapidly changing environment, plant diversity, rising anthropogenic activities, study of their diversity is of prime importance and is required to be investigated. Therefore, our work focussed on documenting the distribution of leafhoppers in relation to elevation gradient in order to establish the species richness and abundance.