COMMON NAME

Weevils-general

Order

Suborder

Family

Genus

Species

Alias

Coleoptera

Curculionoidea

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Description

The distinguishing feature of these beetles is their long ‘snouts’. Most adults are black, grey or brown. The legless larvae are usually a light colour with a brown head. Species include: -sweet potato beetle weevil (Cylas formicarius) -elephant weevil (Orthorhinus cylindrirostris)

Adult size: 3-12mm

Out and about

Generally like warmer climates and are around in spring when the weather warms up.They are most active late in the day. There are more than 60.000 species around the world with higher concentration of species in tropical regions. In Australia they occur everywhere except the most inhospitable inland regions.

Reproduction and Life cycle

In spring the female will lay up to 330 eggs on the ground. Once hatched, the larvae will burrow into the soil where they feed on the roots of plants. Larvae spend winter in the ground and emerge as adults in the spring. Larvae spend winter in the ground and emerge as adults in the spring. Eggs are also laid individually within grains or seeds. The larvae will feed on the grain and pupate inside the husk emerging as an adult from the grain. This is where they are a pest in stored grains as they can continue to mate and lay more eggs. With each female laying 300 eggs it easy to see how quickly they can ruin the harvest.

To deter

Practice good ‘housekeeping’; keep weeds down, maintain healthy plants, rotate crops and plant legumes after weevils’ preferred crops have finished to starve them off.

To control

-spray with pyrethrum -spray with neem oil

Plants to repel

Plant catnip or throw some leaves around the plants.

Plants to attract

Predators

Why they are a Pest

Both the adult and their larvae are problematic. The adults will eat leaves. The larvae cause the most damage as they live in the soil and eat the roots of plants. Many weevils are host specific and have names reflecting this eg. Mango seed weevil (Sternochetus mangiferae) They can be found on curcurbits, parsley, tomatoes, eggplant, beetroot, carrot, potato, strawberry, cabbage, broccoli and lettuce. Weevils are a serious pest in the agriculture industry feeding on grains such as wheat, barley, rye, oats and also grape vines. They will get into the stored grains and are common in foods made from grains like pasta.

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