Pests to look out for

Australian Plague Locusts (Chortoicetes terminifera) are nearing their final stages of nymphal development and have already commenced fledging in some regions. Where hopper bands are still present, landholders should aim to control these as soon as possible to prevent them reaching the adult stage. Adult locusts can travel large distances in search of food and any crop with some green material remaining is at risk of damage. In cereals, locusts can cause large losses when they chew through the last remaining green part of the stem, just below the heads. For more information on the current locust situation, refer to the APLC website.

Armyworms (Family: Noctuidae) can be problematic to grasses and crops at this time of year. They sometimes feed on the remaining green material just below the maturing head of cereals, causing heads to fall. Ripening barley crops are generally worst affected. The first visible sign of armyworm caterpillars is often their green to straw-coloured droppings, about the size of a match head, found on the ground between cereal rows. Armyworm caterpillars are fat and smooth, and can be distinguished by three parallel white stripes on the collar just behind their head.

Rutherglen bugs (Nysius vinitor) are common native insects that attack a wide range of weeds and crops including lucerne, canola, wheat and sunflowers. They are well adapted to dry warm weather and are often most damaging to moisture stressed plants. Adults can also become a grain contaminant when in high numbers. Highest numbers of Rutherglen bugs are often observed along crop perimeters. Adults are 4 mm long, have clear wings and are narrow bodied. They are grey-brown in colour, have two prominent black eyes and are very mobile.

Cereal aphid (Rhopalosiphum padi) numbers appear to have remained relatively low to date and favourable growing conditions have meant there have been few issues this year. However, given this season will extend further into summer than in previous years, there is still time for aphids to build up in some regions. Remember that feeding damage and potential yield losses from aphids will depend on many factors. Losses are generally more severe when crops are already moisture stressed, whereas sufficient moisture availability may enable crops to withstand moderate-high aphid populations with little or no yield penalty.

Several beneficial insects are prevalent during spring/early summer and can play a key role in pest control when low to moderate numbers of pests, such as aphids and caterpillars, are present. Some beneficial insects that have been encountered across many districts in the past few weeks include damsel bugs (Family: Nabidae), hoverflies (Family: Syrphidae), parasitic wasps (Order: Hymenoptera), ladybird beetles (Family: Coccinellidae) and lacewings (Order: Neuroptera). It is worthwhile considering numbers of beneficial insects before deciding on appropriate control strategies.