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Tuesday, May 5, 2015

Diabrotica undecimpunctata

W. spotted cucumber beetleSay that three times really fast, will you? Can you? A long time ago I read in one of those “Believe It or Not” books that if one were to put all the Earth’s vertebrates in one pan of a scale and then all the world’s insects in the other, the scales would tip in the insects’ favor.

Yes, this gardener knows there are a lot of bugs out there and a good many of them are on the march to my garden. Just the other day I noticed shrinking foliage on my prize gooseberry bush, several bare branches with stems minus their leaves and fruit. Immature berries nipped from their stems lay beneath the bush. I bent close to investigate and thought I heard the faint sound of insect mastication. Probably my imagination, but what I did find was a host of green caterpillars, camouflaged, going about their guerilla warfare, at one with the color of the vegetation they were feeding upon…consuming their cover, you might say. The currant leaf worm (larva of the sawfly) attack my gooseberries a couple of times per summer but never this early in the season. My large gooseberry bush was crawling with the fat, green grubs, reminding me of a movie line I heard years ago, a film in which an entire Zulu nation was about to attack a group of  white explorers: “They are many, like leaves on a tree,” one of the scouts reported. I tried picking the worms off and giving each a hearty squeeze between thumb and forefinger but soon gave up. (One website I visited suggested plucking off the grubs and dropping them into soapy water. Sorry, I have neither time nor inclination to give my garden bugs a bath.)currant leaf worms But at dusk last evening, rain in the forecast, I went to the bush and bathe them I did with some no nonsense, foul smelling stuff ending in  the suffix “thion.” This morning the ground beneath the bush was dotted with the deceased. Won that battle….

But it’s the midsummer war I’m fearing, another incursion of a horde of Diabrotica undecimpunctata, the Western Spotted Cucumber beetle. (Another mouthful I dare you to say three times fast.) Tualco Valley has been invaded by these beetle buggers, causing, for starters, crop losses at Willie Green’s Organic Farm and damaging Frohnings’ silage corn. I first noticed the pest in our 2013 garden. In early fall I observed some on our dahlias,  a variety I had paid seven dollars for and nursed along for two years. The dahlia, a light lavender color (reputedly the closest to “blue” of any dahlia variety), no sooner opened its first bud than two or three of these little varmints set to work perforating the petals of the delicate blossom before the blue had a chance to color up.

Last year in late August the beetle moved in and stayed until the first frost. The bugs proceeded to wreak havoc on the garden, preferring the pole beans; they chewed notches in the pods and chewed the leaves into doilies. I had tried the Three Sisters combination: squash, beans and corn, using the latter as poles for the beans. The beetles pounced on the bean vines, ravishing them, and then turned to the leaves of corn, which they soon filigreed. The dahlias came next, then the zinnias. I counted as many as a half dozen beetles on one dahlia blossom. They feasted on the tender petals; the result: each flower looked like it had been peppered by birdshot. I was helpless against them, couldn’t spray because my bees were foraging the dahlias for pollen. We were unable to salvage a single bouquet from the entire patch. Evenings when the sun was low, the air was filled with the glint of hundreds of  wings, bugs moving at will from beans to dahlias to zinnias.

A while back Matt Frohning and I commiserated on this beetle onslaught. According to Matt, cucumber beetle larvae feed on the corn roots; as adults, the bugs feed on the corn plant itself. The Frohnings and other Valley farmers have had to spray their fields with some sort of pesticide (organic, I’ve been told) to combat this voracious crop consumer.  I wish them luck and need  more than a little of my own as the garden season approaches. If they win the beetle war, perhaps I’ll be a victor by proxy here in our garden.

I know they are out there again, poised, mustering their legions. On my Valley walks I’ve seen them already on warm days as early as February, flitting back and forth across Tualco Road, hungrily questing for the first dandelions. beetle pest

Strange thing about the cucumber beetle, though…I have yet to see a single one gnawing on my cucumber vines. A bug, however, by any other name can still be a pest.

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  1. hahaah - there everywhere in the valley - theve been at my places too for years now - don't be stingy terry - just plant more and extra so they can co-exist and have there share too and enjoy tualco valley with us all.

    1. Matt, I've said this many times and will say it again: robins, if you want some blueberries, pitch in and do some work; cabbage butterflies, help yourselves to a leaf or two of cabbage, but how about a helping hand first; currant worms, how's about doing a little pruning and weeding before you chow down, eh? Snails and slugs...same thing goes for you. "Sharing?" You know what the word means, don't you, Matt? I hate freeloaders. TMJ

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  3. Oh great, I have something to look forward to in my garden. Maybe your new chickens can help out with that problem? Can't say they won't chow down on your plants and bushes though. These green caterpillar things is what I was fighting at the end of the summer last year and my chickens enjoyed them:

    1. Paula, just what sort of vegetation were your little green 'pillars foraging on? If they were cole plants (kale, cabbage, broccoli, etc.), you're dealing with Pieris rapae, the cabbage butterfly. What I have on my gooseberries is another pest altogether. Neither of the two have wreaked the havoc in my garden as the cucumber beetles. Someone told me if I have chickens, I'll have no bugs in my garden. Is that because I'll have no garden either? Thanks for reading. TMJ

    2. It was mostly stuff that was growing in the greenhouse. Some kind of collard I think though I never did figure out what that particular plant was. They also chewed up my broccoli so probably was a cabbage butterfly.

      Hah yes I think that may be true. The chickens would most likely eat the garden along with the pests but I'm afraid to test that out. I do let the girls out in the garden during winter and they enjoy digging up hibernating bugs and worms in the garden beds which probably reduces the bug population a bit at least.