Mirid bugs (Hemiptera: Miridae) are important pests of Eucalyptus (Myrtaceae) trees in Indonesia. Young Eucalyptus plantations are mainly affected by Helopeltis spp. Damage by Helopeltis resulted in die-back of young shoots, curling, deformation and drying usually, irrespective of the clones. In North Sumatra, damage in Eucalyptus is associated to Helopeltis bradyi Waterhouse despite the presence of H. theivora Waterhouse in the region. Important alternate host plants recorded as reservoirs of H. bradyi in vicinity to Eucalyptus plantations were Persea sp. (Lauraceae), Coffea sp. (Rubiaceae), Psidium guajava (Myrtaceae), Ludwigia sp. (Onagraceae), Clidemia hirta (Melastomataceae) and Theobroma cacao (Malvaceae). Leiophron sp. (Hymenoptera: Braconidae) was reported as an important parasitoid with parasitism of 41.86% on the H. bradyi nymphs and 17.07% on adults. Helopeltis theivora was recorded as the only species affecting Eucalyptus plantations in Riau Province, so far no other Helopeltis sp. has been identified in Riau. Ragwelellus festivus Miller and Ragwelellus sp. were reported for the first time damaging Eucalyptus trees in North Sumatra, Riau Province and East Kalimantan regions of Indonesia. Arthriticus eugeniae Bergroth was also reported for the first time damaging matured Eucalyptus trees along with Ragwelellus in North Sumatra and Riau Provinces.