The total amount of the identified phenolics was similar in leaves of both cultivars noninfested by the insects. However, higher content of ferulic acid and o-coumaric acid was found in the less acceptable triticale (Lamberto cv.) than in more acceptable Marko cv. After infestation an increase in content of the most phenolics was observed. The cereal leaf beetle brought the highest changes in the gallic, chlorogenic, salicylic, syringic and ferulic acid. The grain aphid feeding resulted in the increase of gallic, chlorogenic, vanilic, caffeic, syringic and salicylic acids. Moreover, much higher induction of phenolic biosynthesis occurred within seedlings of Lambero cv. than in Marko one. The differences in phenolic acids level within triticale tissues induced by the chewing and sucking-piercing insects are discussed.