The black field earwig

Nala lividipes (Duf.) has for many years caused losses to field crops on black soil in southern Queensland [cf. RAE A 21 106], but damage due to it appears recently to have become more widespread. This earwig lives in the superficial loose, cultivated soil and normally feeds on organic material such as decaying stubble, but when populations increase in summer, they may attack the roots of seedlings and young plants. Maize is the crop most frequently attacked, but sorghum and beet are often, and summer and winter cereal crops sometimes, damaged. Damage has been recorded on maize plants up to 2 ft high, and at this stage the nymphs feed on the prop roots and the plants may in consequence be blown over by wind. The eggs are laid in the soil in groups of 25-30, and development occupies all the summer. Populations decrease towards winter, and the females appear to overwinter in the soil and to oviposit in spring. Preliminary field trials indicated that the application of a dust of γ DHC (lindane) at 1 oz toxicant/20 000 ft of row to the furrows at planting enables the crop to become established. Control measures need be undertaken only where infestations high enough to be injurious are present, however.