Carabids can eat a substantial amount of seeds of weeds per day and are considered as credible biocontrol agents for the regulation of weeds in arable fields. Carabids species belong to either granivore, omnivore or carnivore trophic guilds and we expected each of these to have specific patterns of weed seed consumption and specific responses to biotic interactions. These differences will impact the total predation rate of a carabid community and may also explain why it is difficult to predict the efficiency of carabid biocontrol service. To test this expectation, we looked at the consumption pattern of two species of carabids species common in arable fields, one known as generalist (P. cupreus) and another known as specialist (H. affinis), for four species of seeds of weeds. Consumption was scored for 13h using no choice tests. The effect of biotic interactions, was assessed by looking at the foraging behaviour of the two carabid species under 4 different experimental conditions: i) predation risk; ii-iii) intra- and interspecific competition; and, iv) control. Our results show that the consumption pattern of the two carabid species differs markedly. P. cupreus eat faster but express strong feeding preferences while H. affinis feed slowly but eat all species of seeds equally. Moreover, while the consumption pattern of P. cupreus remains stable between the experimental conditions, H. affinis change their behavior, eating more rapidly when faced with a risk of predation.