The been weevil
Have some bean weevils invaded your reserves? Discover in this file a set of answers and tips that will allow you to fight this insect at best.
Who's the bean weevil ?
Latin name: Acanthoscelides obtectus
Size: 2 to 5 mm
Location: kitchen and reserve
Period: all year
What you need to know about the bean weevil
This bug only attacks beans. The female adult lays her eggs (up to 40 eggs) on the still on foot pods. After 3 to 15 days, the larva will grow in the grains. Its growth lasts about three weeks, then it cuts a circular outlet operculum into the grain wall and nymphoses to give, 12 to 25 days later, an adult capable of reproducing again. There can be up to three generations.
Contamination can therefore quickly spread throughout the dry beans reserve.
The larvae only get into dry beans, so fresh beans are nothing to worry about. By digging galleries inside the grains, they become unfit for consumption. You also cannot use them as seed. The harvest is thus lost! Be aware that there are several varieties of bruchids that attack different plants. Acanthoscelides obtectus affects beans, other Bruchidae attack lentils, broad beans or peas.
It is a true scourge for professionals, especially for cooperatives, stockpiling and processors.
How do I remove the bean weevil ?
It is at the larval stage, when the weevil begins to develop in the pods, that the control proves to be the most effective.
1 - Carefully observe beans and pods when you save beans and burn them (don't contaminate your compost) if you see eggs or traces of larvae attacks (their holes are much smaller than those of adults).
2 - Whenever possible, store your beans in airtight jars. The freezer, for those who have one, is a very effective weapon, the larvae not resisting beyond 24 hours (in the past, the bundles of grain beans were hung in the dry and freezing to kill the weevils during the winter)
Other effective ways of fighting:
- a few caieux of garlic not peeled in each container
- tansy decoction: You can deter insects from laying eggs on your beans with a tansy decoction. The smell of tansy has the particularity of repelling these pests. For this, harvest 300g of tansy that you chop finely and place in a non-metallic container. Pour a liter of boiling water over it, then cover. Leave to infuse for 24 hours. All you have to do is pour this solution into a bottle using a strainer. Use your decoction as a spray at the foot of your beans.
- ignite an alcohol-impaired cotton just before closing the jar hermetically (condemn the asphyxia noisy by burning oxygen)