Crop Weevils: The Back Pocket Guide

Image of the cover of the Crop Weevils Back Pocket Guide.

Weevils are a diverse group of beetles that are commonly found in Australian grain crops. Adult weevils appear very different to the larvae. Adults have a hardened body, six prominent legs and an elongated, downward curved head forming a ‘snout’. The larvae are legless, maggot-like in shape and may be confused with fly larvae. Weevil larvae possess a small, hardened head capsule.

Crop weevils feed on vegetative parts of crop plants including the roots, stems, shoots, buds and leaves. Both adults and larvae can be damaging to plants, depending on the species, crop type and time of year. Typical feeding damage commonly observed is scallop-shaped holes along the edges of leaves. Weevils can be difficult to control with chemicals due to their secretive habits. Several species are also patchy in their distribution within paddocks. For some species, seed treatments and foliar insecticides can provide a level of control. Weevils are typically favoured by minimum tillage and stubble retention. Cultivation, burning and reducing the amount of stubble will reduce the suitable habitat for weevils and reduce their number.

Identification of crop weevils is important when making control decisions. The distinctive appearance of weevils makes them unlikely to be confused with other beetles. However, distinguishing between the many species of weevil is challenging. This guide is designed to assist growers in identifying the most commonly observed weevils found in the southern and western cropping regions.

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Region South, West, North