Helopeltis theivora Waterhouse, pest of tea, is emerging as a commonly occurring major pest of cashew (Anacardium occidentale L.) in recent times. The field observation revealed Chromolaena odorata (L.) R.M. King & H. Rob. weed support as an alternate host of this pest during off season of cashew. Biology of H. theivora on this weed was studied for the first time. The incubation period of eggs was 10.5 ± 1.2 d. The 1st, 2nd, 3rd, 4th and 5th nymphal instar developmental times were 36.11 ± 9.52, 43.29 ± 7.35, 27.15 ± 8.41, 41.31 ± 10.13, and 73.91 ± 5.67 h, respectively. Survival percentage of eggs was lower (60.53%) than nymphal instars. Adult females and males lived for 22.6 ± 3.29 and 11.8 ± 1.64 d, respectively. Females showed dynamic patterns of fecundity with the number of eggs laid per female ranging 19 to 34. Longevity and fecundity of H. theivora on this weed were significantly lesser when compared on cashew. Egg parasitoids viz., Telenomus sp., Chaetostricha sp. and Erythmelus helopeltidis Gahan were recorded from H. theivora eggs on C. odorata for the first time. For better management decisions, it is important to know about this mirid biology, particularly their life cycle on their alternate hosts so that the right assessment can be made before taking up spray.