Plants, Stone, California Landscapes


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Lemon Zesting Rodents?

In one of the gardens where I’m working this summer, all of the citrus have had the peels eaten away by some kind of animal. I’ve never seen this before; it looks really strange. The garden is near Berkeley’s so-called ‘Gourmet Ghetto’ in a relatively urban neighborhood that probably has some rats lurking about. Do rats do this? Do they like lemon zest? It doesn’t look like something squirrels or birds would do, and I can’t think of anything else that would do this.

— Update 8/30 — I asked at one of the nurseries and someone there said, yep, it was rats. Kind of gross.

Another Bee Tree

And in another quick follow up on a recent post, we did a consultation at another house with a wild bee hive last week, this time in an old willow. Maybe bee trees are more common that I thought. This hive was much more exposed than the one in the silver maple, and the bees were a lot less comfortable with me sticking my camera up close, forcing me to retreat pretty quickly. These bees over-winter on-site, the client said, visibly present, but with a very low level of activity. They’ve been in the willow for six years, and the fruit trees in the yard have, predictably, had bumper crops ever since. When the tree (now moribund) dies, the owners are planning to plant a vine to grow up the trunk to keep the wood shaded and the bees happy.

The Bee Tree

‘…a hole in back you could put your fist in, if it were a small fist and you wanted to put it there…’ Hemingway, A Natural History of the Dead

The last few weeks we’ve been working in a yard that has a wild bee hive in an old silver maple. Apparently, they vanish each winter and a big, noisy swarm returns in the spring. On cold days, the hole in the trunk steams faintly. The bees are mellow in the morning, but in the late afternoon they make a loud buzz like every cartoon representation of an angry bee swarm that I’ve ever seen. It’s a little disconcerting, though they are far too busy to pay any attention to me.

I bet there’s some nice honey in there, but I’m sure not going in after it.

Spittle Bug Season

Spittle Bugs in the Ninebark Buds

Spittle Bugs in the Ninebark Buds

April is the start of spittle bug season in our garden. Spittle bugs are the little froghopper nymphs putting drips of saliva on a lot of our plants, a weird thing which I don’t particularly like, but find kind of intriguing. Apparently, the nymphs suck out the water in the xylem of the stems (as opposed to the more nutrient-rich phloem that their aphid relatives and most other sucking insects prefer), and they need to process a lot of watery stuff from the xylem to get enough nutrients; at some point these unappealing spittle cocoons evolved as a protective byproduct of all that excess water.

The nymphs like new growth and especially bloom stalks, and as April is our biggest month for bloom stalks and new growth, April is also our biggest month for spittle bugs. As I understand it, the small orange nymphs are young nymphs, the yellow ones are older, and the larger greenish ones are in the last phase before they morph into adults. Most of ours are orange right now. We’ll have the nymphs for a month or two, and then later we’ll get the hoppy adults. Neither one seems to affect the plants much.

Close ups of spittle and a butterfly are below. (more…)

Golden Mummies

golden mummies & aphids

golden mummies & aphids

Please excuse the rather unpleasant photo. Aphids are gross, but golden mummies are one of the best things I ever learned about IPM.

We’ve had a couple of outbreaks of aphids this spring, first with the lupine when it put out a big flush of new growth and now on our kales as they begin to bolt. Golden mummies are the brownish, mummified carcasses of parasitized aphids; wasps lay their eggs in the aphids and the larva eat the aphids from the inside, leaving the dried husks. If you aren’t familiar with them, click on the photo and you should be able to see the difference. In the garden, another way to tell the difference is that aphids move and mummies don’t.

When you see an outbreak of aphids, the presence of golden mummies is one sign that natural predators are present. Count the aphids and golden mummies on a leaf, and, if the outbreak includes at least 10 percent golden mummies, the natural predators will deal with the outbreak for you. Spraying would kill the natural predators along with the aphids and therefore be counterproductive, though aiming a spray of water against the aphids to knock them off (which actually kills a large percentage of them, while not harming the beneficials) is okay if you want to speed the process. 

In the photo, I count 14 golden mummies (mostly on the right, but three in the population of aphids on the left) and estimate about 100 aphids, so our IPM is working. Our earlier outbreak on the lupine was the same way, and it resolved itself without intervention.

ryan 4/22

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