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.

Sorghum head bug, Calocoris angustatus Leth. (Hemiptera: Miridae) is an important insect pest of sorghum in the semi-arid tropics. A technique to screen for resistance to head bugs under field conditions was tested. Planting infester rows of susceptible cultivars (CSH 1 or CSH 5), 20 days before the test material or planting early (40–45 days) flowering lines (IS 802, IS 13429 and IS 24439) along with the test material, split planting of test material at 15-day intervals, grouping test material according to maturity, and use of sprinkler irrigation to maintain high humidity, were found effective in increasing the efficiency of screening and selecting for resistance to head bugs.

A headcage technique to screen for resistance under no-choice conditions has also been developed. Panicles infested with 10 pairs of bugs at pre- and half-anthesis, result in maximum population build-up and grain damage under headcage. This technique is useful for confirming the resistance observed under field conditions.

Under natural infestation, five genotypes harboured relatively lower head bug numbers than the susceptible checks, but only three (IS 17610, IS 17618 and IS 17645) maintained their level of resistance under the headcage. Seed germination was > 70% in these genotypes compared to < 10% in CSH 1 and CSH 5.

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.