INTRODUCTION One of the major factors responsible for good quality and productivity of agricultural and horticultural crop is pollination for which, a number of insect pollinators viz., honeybees, bumble bees, and solitary bees etc. helps in transferring pollens from one flower to another flower (McGregor, 1976). Out of a number of insect pollinators, bumble bees are the superstar of pollinators also known as teddy bear of insects. Bumble bees are most diverse group of pollinators in temperate regions and only 34 species out of the 250 species are found in tropics (Williams, 1998). The bumble bees are more efficient and reliable pollinators especially under protected conditions (Mackenzie, 2009), helping in high quality fruit production due to their high speed of pollination, buzz behaviour and efficiency at low temperature and sunlight (Paydas et al., 2000). Use of insect pollination within greenhouse, especially bumble bees gave cost effective and attractive substitute of manual pollination (Velthuis and van Doorn 2006). An external and internal environmental condition along with foraging efficiency of bumble bees has an impact on required pollination of various crops. Foraging activity of bumble bees was important to serve as successful pollinators under these greenhouse conditions as compared to honey bees (Wolf and Moritz, 2008).Bumble bees can fly and pollinate flowers under cool conditions due to their thermoregulatory abilities (Corbet, 1995). They have better adaptive qualities for pollen and nectar collection near their hives and preference increases in small patches with flower abundance (Sowig, 1989). Abak et al. (2000) conducted a pollination experiment on bumble bees and observed that their activity increased between 9:00 to 11:00 am, the peak activity was observed between 10:00 to 11:00 am then decreased gradually and they stopped between 13:00 to 14:00 pm. They started foraging again in afternoon between 15:00 to 18:00 pm. Spivak (2000) also reported that bumble bees are effective foragers than honey bees because of their ability of buzz pollination. Bumble bee hang onto flower and buzz it by vibrating their muscles that control flight. Bumble bees are the most efficient pollinators not only for wild plants, but also for pollination services used in outdoor and greenhouse orchards and horticulture. Foraging behaviour studies conducted on four species of bumble bee in England revealed that the high foraging activity occurs at 1000-1100 h. The pollen collection was also high during noon hours (Free, 1955). Hines et al. (2007) also studied foraging activity of B. pullatus and observed foraging range within 2.6-9.5 bees per minute across different time period, with the highest activity in the morning (07:00-10:00 am). Pollen collection was also highest from 07:00 -10:00 am and declined throughout rest of the day, while the foraging rate for nectar foragers remained relatively constant. The percent of incoming foragers that carried pollen in a sample period ranged from 2.4 to 44.2 per cent. There was no significant relationship between ambient temperature and number of all foragers. Foraging trips lasted from 30-70.5 minutes, with a mean of 51 and a median of 49.5 minutes. Kashyap (2007) recorded maximum bumble bee activity during 0600-0700 and 1600-1700 hours while, minimum during 1200-1300 hours. Stelzer and Chittka (2010) reported that bumble bee activity was restricted between 08:00 to 23:00 hours. Thakur (2018) observed the peak incoming and outgoing activity during 1700-1800h (4.63 bumble bees/five min) and 0900-1000h (4.73 bumble bees/five min), respectively and minimum during 1300-1400h. Nayak (2018) also reported maximum activity during 1600-1700h while minimum during 1300-1400h. Keeping in view all these points, present studies were undertaken to investigate the foraging activity of Bombus haemorrhoidalis Smith kept under shade net house conditions. MATERIALS AND METHODS The experiment was conducted in experimental farm, Bagaur under the Department of Entomology, College of Horticulture, Dr YS Parmar University of Horticulture and Forestry, Nauni-Solan (H.P.) in the first week of June, 2018. Foraging B. haemorrhoidalis queens were collected from field during early spring and then brought to laboratory for their in-vitro rearing. These captured queens were kept in wooden domiciles under controlled conditions (25 ± 2ºC temperature and 60 - 65 per cent relative humidity). Proper cleaning and daily feeding of 50 per cent sugar syrup and freshly collected pollens were given to colonies. After the production of first brood i.e., at the end of May, 2018these colonies were transferred to field under shade net hose conditions for their establishment and acclimatization. Under field conditions, small wooden boxes consisting of colonies were kept in Langstroth hive, which was kept on iron stand at the centre of the cage. Plastic pipe was also fitted at the entrance for easy movement of bumble bee foragers. The colonies were provided proper feed for first 2-3 days by closing their entrance. After 2-3 days, data on incoming and outgoing bumble bee forgers was noted down. Data recorded on various parameters were analysed statistically with no transformation in R.B.D. design by Gomez and Gomez (1986). RESULTS AND DISCUSSIONS Incoming activity of B. haemorrhoidalis foragers. Data recorded on incoming activity of bumble bees under shade net house conditions is presented in Table 1. The data showed that bumble bee activity was significantly low during initial months of shifting and development of colonies being 0.37, 0.55, 0.57 bumble bees/five min, respectively in May, June and July. The average activity of bumble bees in the field peaked during October (2.10 bumble bees) followed by September (1.76 bumble bees) which was at par with the activity observed during November (1.59 bumble bees) (Fig. 1). The incoming activity of B. haemorrhoidalis varied greatly in the months of May to December during different day length. Irrespective of months, the B. haemorrhoidalis activity was maximum (1.61 bumble bees) during 0900-1000h followed by activity observed during 1800-1900h (1.27 bumble bees) which was statistically at par with the activity observed during 0600-0700h (1.14 bumble bees). Significantly low incoming activity was observed during 1500-1600h (0.82 bumble bees) and 1200-1300h (0.85 bumble bees) which was statistically at par. Outgoing activity of B. haemorrhoidalis foragers. Data recorded on outgoing activity of B. haemorrhoidalis under open field conditions presented in Table 2 revealed that the B. haemorrhoidalis activity was significantly low in the months of May, June, July and December being 0.49, 0.58, 0.65 and 0.60 bumble bees/five min, which were statistically same. However, the average outgoing activity of B. haemorrhoidalis peaked during the month of October (2.10 bumble bees) (Fig. 1). The outgoing activity of B. haemorrhoidalis varied greatly in the months of May to December during different day hours. It varied from 0.11 bumble bees (in December during 1500-1600h) to 3.32 bumble bees (in October during 0900-1000h). Irrespective of months, the B. haemorrhoidalis activity was maximum (1.57 bumble bees) during 0900-1000h. Significantly low average outgoing activity (0.62 bumble bees) was observed during 1500-1600h. The results of the present investigations with respect to foraging activity of B. haemorrhoidalis under shade net house conditions are in line with the findings of earlier workers (Chauhan et al., 2013; 2014; Thakur, 2018; Nayak, 2018). Chauhan et al. (2013; 2014) recorded maximum incoming and outgoing activity of B. haemorrhoidalis at hive entrance during 0900-1100h and 1600-1800h and minimum during 1300-1500h.Later, Thakur (2018) observed the peak incoming and outgoing activity during September and October months which was statistically at par. However, the minimum activity was observed in May. According to day hours, the peak B. haemorrhoidalis incoming and outgoing activity was observed during 1700-1800h (4.63 bumble bees/five min) and 0900-1000h (4.73 bumble bees/five min), respectively. On the other hand, the minimum activity was reported during 1300-1400h. Nayak (2018) also reported maximum activity during 1600-1700h while minimum during 1300-1400h.