Detailed biology of the sorghum earhead bug, Calocoris angustatus Lethierry was studied at Dharwad, India during 1979–1981. Egg incubation and nymphal developmental period ranged from 5.6–11.0 and 10.0–17.0 days, respectively. The duration of first, second, third, fourth and fifth nymphal instars was 2.2 to 3.4, 2.3 to 3.0, 2.0 to 2.8, 2.0 to 3.0 and 2.0 to 2.7 days, respectively. The males lived for 8.9 to 17.6 days and females for 12.2 to 21.3 days. Fecundity varied from 57.7 to 267.1 eggs per female. Preoviposition, oviposition and post oviposition periods varied from 1.2 to 2.1, from 7.2 to 14.0 and from 5.0 to 15.8 days, respectively. All the developmental stages of the bug are described.

The importance of the gram pod borer, Helicoverpa (=Heliothis) armigera (Hiibner) and the earhead bug, Calocoris angustatus Lethierry in the sorghum panicle was assessed. Gram pod borer consumed 2. 364 g of dough stage grains from fourth instar to pupation. A total of 74. 50 grains were damaged during the complete larval period. Grain loss was 14. 32 and 29. 42 g respectively when 50 and 100 nymphs per panicle were confined. When the two species occurred together grain loss was more than the sum of the loss due to each species alone.

The intensity of damage to sorghum panicle caused by the sorghum earhead bug, Calocoris angustatus Lethierry (Heteroptera: Miridae) was studied under laboratory and field conditions. Laboratory studies showed that among the five nymphal instars, fourth instars consumed maximum food (5.06mg/day). In adults, the consumption was thrice that of the fourth instar nymphs. Male and female consumed on average 250.68 and 305.56 mg of food respectively from their second instar nymphal stage till their death. In the field, 1–3 days old panicles were preferred for oviposition when compared with panicles at later stages. Grain weight losses upto 31.54 g/panicle infested with three adults were recorded. Similarly the grain weight per panicle decreased as the number of ovipositing females increased; grain weight losses of 9.72–42.02 g were recorded.

Economic injury level (EIL) by the sorghum earhead bug was estimated for nymphs, feeding adults and ovipositing adults of sorghum earhead bug, Calocoris angustatus Lethierry, using malathion or hexachlorocyclohexane (HCH) as insecticidal control measure. EIL varied according to the insecticide used and the stage of the insect. EIL per panicle was 7.9 nymphs, 5.4 feeding adults or 0.06 ovipositing adults when HCH was used, which increased to 15.1 nymphs, 10.5 feeding adults and 0.12 ovipositing adults when malathion was used for control.

Seasonal incidence of the sorghum earhead bug, Calocoris angustatus Lethierry, was studied by sowing the crop once in 10 days, throughout the year during 1978 and 1979, as well as by sowing it at fortnightly intervals from early “kharif” to late “rabi” during 1979. The bug was found throughout the year except for a few weeks during March, April and May. The milky stage of the earhead was the most preferred stage compared to pre-flowering, a third flowering, flowering and ripening stages. The adults dominated during pre-flowering and a third flowering stages whereas nymphs dominated during milky and ripening stages. The computed seasonal indices were higher during August (230), September (222), October (224) and January (215) which coincided with blooming and milky stage of sorghum in general fields. Correlation studies between the bug population at the milky stage and maximum temperature indicated negative and significant (r = -0.2967) relationship, and positive and significant (r = +0.2727) relationship with relative humidity. Low incidence of bugs was observed on the crop sown during June.