Tuesday, August 31, 2010
Where there were mating milkweed bugs (Oncopeltus fasciatus) there will be a horde of developing milkweed bug nymphs. First a group of very young ones is seen spiraling up a milkweed seed pod. Every source says these bugs feed on the milkweed seeds but I think maybe they feed on the softer tissue of the plant as well; these young ones appear to be sucking on the tender green pod. In order to be feeding on the seeds, their mouthparts would need to pierce through the pod wall and the surrounding fluff to the developing seeds inside. Are their young mouthparts that long?
The growth rate of the nymphs does not seem uniform. You often see groups of mixed stages of development as seen here. I found an abstract of an old article (1976 Oecologia, Natural Food Requirements of the Large Milkweed Bug . . . by Carol Pearson Ralph) that suggests: A. When the seedpod wall thickness prevents the bugs from reaching seeds, O. fasciatus feeds on the plant tissue; B. Nymphs of the three youngest stages often cannot access the nutrients inside the seedpod due to their short mouthparts and so suffer slower growth due to poorer nutrition. Reproduction is also slowed by a vegetative diet. C. It was observed that all ages of bugs seek out the thinnest pod walls; and D. nymphs in larger groups suffered lower mortality rates than those in smaller groups.
The bugs here have aggregated on two sides of a leaf, while one of them separates from the rest to undergo its final molt to adulthood. The freshly exposed new exoskeleton is light colored and will darken and develop the adult markings as it cures in the air.
The aposematically colorful peanut gallery looks on; you can barely see a tiny solid red one tucked under the middle of the rest of the more mature mixed-aged group.
After molting, a black and white transparent shell is left behind on the leaf.
Milkweed bug in a paradise of seeds. It pierces a seed with its long beak to feed. Yet unanswered: how does the bug pierce a seed suspended in mid-fluff given there is no leverage against the seed?
Monday, August 30, 2010
I've had these photos on file for awhile of a honeybee with a red dot of pollen on her pollen pack of otherwise yellow pollen. She is seen here foraging on red buckwheat, Eriogonum grande rubescens. Is the red pollen from another flower or from the aptly named buckwheat?
Now that I returned from a quickie vacation to the beautiful Owens Valley I can spare a little time to investigate further. Pollen comes in lots of colors, not always what you might assume from the flower color or name. I went out back to check out the buckwheat pollen first hand. Most of the flowers are now dried up, but a few spunky stamens persist and I was able to shake out some grains onto my palm. They are red, rather large for pollen in that they felt like small sand grains as I rubbed them around. Using my handy Tasco 30x pocket scope, I could see they are shaped like little concave 3-sided oval purses, very similar to the image seen here for E. hooveri, but smoother. I checked the full range of flower colors I have, from the dark pink flowered through light pink to white, and all of the pollen collected was red or very dark pink.
So the dots of red on the pollen pack are likely to be red buckwheat pollen, unless somebody has another explanation. Why this bee gathered some buckwheat, went to another (yellow) pollen source then back to the buckwheat is beyond the scope of today's investigation.
Thanks Wiki and UC Berkeley for tables and info.
Sunday, August 15, 2010
So it's August and autumn really is just around the corner. You can feel the changes coming even as the beads of sweat gather on your forehead and roll down into your eyes, stinging and causing them to water a little bit.
My daughter bought herself this tomato plant from a guy who grows all sorts of veggies and perennials here locally and sells 'em out of his driveway. Really healthy plants. I'm happy to have inspired my offspring to garden. Her tomato flowers look very hopeful and promising; I'm sure there's enough summer left to bring forth fruit.
A month or so ago I plucked a few gangly shasta daisy stems and stuck them in a vase on the kitchen window sill. They slowly dried there in the summer air, as have rudbeckias, roses, gaillardia and many other blooms in seasons past. I find the dried flowers pretty in a mournful, faded, late summer kind of way.
This morning I noticed in a surprised way that one of the leaves has been skeletonized; there is a geometrid caterpillar working on this old dried up plant. I do remember reading something about monarch caterpillar feed being made from dried milkweed so it's not a huge surprise to find this. Just weird to think of caterpillars chewing on what is essentially hay.
Saturday, August 14, 2010
This time the resident robber fly (Mallaphora fautrix) flew by my ear as I was noticing that my artichoke plant is resprouting from its base. The large fly landed and assumed its characteristic hunting perch on top of a nearby Phlomis fruticosa plant. It was pretty friendly, or at least not too standoffish, and allowed me a few photos as the honeybees busied themselves with the pentas flowers on the shrub next door to the phlomis. Patience, patience, and then like a shot the robber fly sprang up and captured one bee as it left the pentas never to return home.
This wider photo shows the fly atop the plant, which gives the hunter a good view and clear airspace needed for its aerial attacks.
Friday, August 13, 2010
It was inevitable, given the swarms of flies, bees and wasps attracted by the red buckwheat (Eriogonum grande rubescens, which I highly recommend for planting as a nectar source for your garden inhabitants) that spiders would move in to do a little feeding of their own on the reprocessed nectar.
This green lynx (Peucetia viridens) male has caught himself a small bee of unknown species for lunch. Then he skulked off in a picturesque way to enjoy the meal in shady privacy under a cloud of flowers and future meals.
Thursday, August 12, 2010
The mantis in the bathroom was a lively creature and I thought likely to do well having been released to the relative wild of the neighbor's wisteria vine. This exoskeleton left behind is evidence that it has grown at least to the next stage without falling prey to a spider or some insectivorous vertebrate. Yay.
Wednesday, August 11, 2010
The red buckwheat is still blooming and on a recent bright sunny day was attracting this Great Golden Digger Wasp, Sphex ichneumoneus, to feed on nectar. The adult wasp feeds exclusively on nectar, but the female hunts crickets and katydids to stock the underground nest where her young will develop, hidden somewhere in the garden. Fearsome as this wasp might appear, it's quite docile and doesn't seem to mind the attentions of a human observer. The individual in this photo may be a male, based on the mostly black colored hind femur (info found on bugguide post specific to west coast S. ichneumoneus).
I rarely see many of these wasps, just a few each season. Maybe they defend their territory and keep others of their kind out.
Friday, August 06, 2010
An assassin bug, zelus renardii, waits for prey on a sunlit artichoke stem on a recent day.
Have not seen a lot of these yet this year, and looking back in the blog I found I haven't posted on this species since January of last year. They are general predators and are often found hanging out on flowers where pollen and nectar feeders are likely to stumble upon. The assassin waits without moving and stabs its prey with its long piercing mouthparts. The immature assassin bugs feed in the same way and in the same places.
Update: Here's a photo of a young one hanging out on a phlomis leaf waiting for prey.
Monday, August 02, 2010
Here's a nearly mature green lynx spider hanging out on a nasturtium flower. So what, you may ask.
Our unusually mild summer has failed to beat down the cool-loving nasturtiums growing in a summer-sunny spot. The unusually cool weather seems to have slowed down the growth of green lynx spiders until recently as the warmer days have brought on a relative abundance of insects and a burst of growth in the spiders. So the convergence of Peucetia viridans in a later stage of growth with Tropaeolum majus in bloom was not a likely thing, and in fact has never been seen on these premises before now, the Unusually Cool Summer of 2010.
Sunday, August 01, 2010
The western tiger swallowtail, Papilio rutulus, is different from the giant swallowtail (Papilio cresphontes) in the time it spends in relatively stillness while feeding or perched on a flower. I was able to get so close to this one, feeding on the lantana, that I could hear and appreciate the lush swoosh of its wings as it waved them--repeatedly--past the foliage and flowers while feeding.