Monday, November 23, 2009

What could be worse than slugs? Bean weevils!

Now that fall is upon us and the garden is pretty much ready for winter, I decided to tackle our large harvest of dried wax beans in order to remove the dried beans from the seed casings. We acquired the allotment garden at the end of July, and the large plot of wax bush beans our predecessors had planted were already overripe and no longer edible as green beans. So upon the advice of a dear elderly experienced gardener, I left the beans on the plants until they were thoroughly dry. She had said that after harvesting I should spread them on newspaper to further dry, up to the point where the pods were stiff and crackling. So that's what I did.

Then one dreary evening (it's already dark here in Germany by 5 p.m.) I settled in and began to remove the seeds.

The beans were quite pretty, shiny white with black markings. Still, my husband suggested we cook up a batch as bean soup to see if they really tasted good as dried beans before shelling the whole two bucketfuls. 

When I washed a bowlful, I noticed an insect or two rising to the surface of the water without thinking much of it. After all they were organically grown beans from the garden. But after I had soaked them for a while and they had somewhat expanded in size, I noticed that every single bean seemed to have a small round hole in it. I took one out, cut it open, and inside there was a tiny live beetle! It turned out there was a beetle in every single bean! Not a worm - a beetle. Being soaked for a few hours hadn't phased them. Horrified, I dumped the entire lot onto the compost without thinking to grab my camera and get a photo.

After researching on the internet I discovered that they must have been bean weevils. I found a great picture  of them on a Danish website by searching for the Latin name Callosobruchus maculatusAfter discovering that the website had German and English versions, it turned out to be a website run by people who have a mail order business for poisonous dart frogs, geckos, and other terrarium animals they breed themselves. So why do they have such a professional photo of bean weevils on their site?? Because they raise them, too, as food for the frogs! Here's the picture, at a later stage than my beans were:

The creatures have an interesting life cycle, spending almost their entire life inside of the bean they call home. They crawl out to mate and lay eggs on the beans, and the hatched larva then chew their way in where they pupate. So will we now have trouble growing beans without using insecticides, which we are determined not to do?

 If anyone has advice on this I'd be grateful. I've been trying to psych myself into liking our slugs (see my post on snail whispering), but I don't think I can get close to a bean weevil. Maybe I'll get in touch with those Danes about a business proposition!


  1. Oh, wie traurig, da scheint ja nun die Ernte dahin zu sein.Schade drum, schlimmer als Schnecken ist der Käfer sicher nicht, allerdings hatte ich ihn im Gegensatz zu den Schnecken auch noch nicht im Garten..... der fehlte noch zu meinem Glück. Er scheint aber eine interessante Biologie zu haben, wie Du auch andeutest und wie man im Netz auch nachlesen kann, allerdings gibt es wohl auch kein Kraut, was gegen den 'Bohnenkäfer' gewachsen ist.
    Aber er muss ja nächstes Jahr nicht unbedingt wieder in solchen Mengen auftreten; so war es beispielsweise bei den Blattkäfern, die die Pfefferminze in meinem Garten fraßen. Dieses Jahr habe ich im Gegensatz zu den Vorjahren keinen gesehen, ohne irgendetwas gegen ihn unternommen zu haben.
    Ich habe Dir übrigens ein Stöckchen zum Thema 'Zierpflanzen' zugeworfen, Schau mal in meinen Blog,

  2. Hallo Sisah, Du machst mir Mut, dass das nächstes Jahr nicht unbedingt so wieder sein muss. Dein Wort in Gottes Ohr. Ich schaue mir Deine Webseite gleich an. Auf Pfefferminze hatte ich noch nie Ungeziefer, dachte, sie seien immun. Offenbar nicht. Viele Grüße Barbara

  3. I wish I could help you but this is the first time I am seeing this.It is good of you to highlight them in your informative and interesting post. It is common for me to find weevils in rice grains and flour, where we just wash or sieve them away but your bean bugs look different and I too would do the same thing that you have done.

  4. Just today one of my children looked at this post and almost gagged. Wonder if he'll ever want to eat anything from the garden again.

  5. Why not send away for some of those frogs or lizzards?

  6. I wonder if they have been multiplying while you left them to dry? Maybe your container needs to be beetle proof next year?

  7. According to what I read about their life cycle, beetles (that is their larva) were probably inside the beans long before I harvested them, so a tightly closed container wouldn't have helped in this case. The beans were growing a large monoculture area, so I think perhaps mixed gardening will help.

  8. I don't think it's a good idea to throw your infested beans into your compost.
    "The adult weevils overwinter in plant debris and coarse vegetation and move onto peas, beans and other leguminous plants in early spring."
    The bean weevil is distributed worldwide. It has been reported across Canada where it attacks stored beans as well.
    Man lernt immer wieder etwas Neues. Ich hoffe, dass die nächste Ernte ohne weevils ist.
    - Cheers Gisela.

  9. Hallo Gisela, Thanks for the tip. Next time I'll put any infested beans into the garbage. Danke auch für die guten Wünsche, Barbara

  10. According to my Seed to Seed book, you should put the dried, shelled bean seed in a tightly sealed container in a deep-freeze for five days. That will kill the beetles, and will allow you to eat the beans and/or to re-plant the seed the following year.

    Make sure not to open the containers until they've come to room temperature, or you'll get condensation on the inside and ruin the seed.

  11. You might try DIATOMATIOUS EARTH or D.E., the food grade kind, that you can sprinkle on plants, under plants, your house, pets or livestock as it will not effect humans.
    See: for video. I bought a 50 LB. bag of food grade...this should last me forever.
    I have puffed it onto my house to deter boxelder bugs & used D.E. along with Sol-u-mel (from Melaleuca Alternafolia plant of Australia--company of Melaleuca in U.S.A.)to get rid of bed bugs my daughter bought home in a new bedspread that obviously had a different home first before ours.
    Diatomaceous earth is made up of the cell walls/shells of single cell diatoms and readily crumbles to a fine powder. Diatom cell walls are made up of biogenic silica with sharp edges but the fine powder is super fine, but drying to touch.
    Diatomite is also used as an insecticide, due to its physico-sorptive properties. The fine powder absorbs lipids from the waxy outer layer of insects' exoskeletons, causing them to dehydrate. Arthropods die as a result of the water pressure deficiency, based on Fick's law of diffusion. This also works against gastropods and is commonly employed in gardening to defeat slugs. However, since slugs inhabit humid environments, efficacy is very low. It is sometimes mixed with an attractant or other additives to increase its effectiveness. Medical-grade diatomite is sometimes used to de-worm both animals and humans, with questionable efficacy. It is most commonly used in lieu of boric acid, and can be used to help control and eventually eliminate cockroach and flea infestations. This material has wide application for insect control in grain storage. It has also been used to control bedbug infestations, but this method may take weeks to work.
    --CJB of Nebraska/USA