Showing posts with label insects. Show all posts
Showing posts with label insects. Show all posts

20 August 2009

Too much beauty

There's just too much beauty in the garden, I simply must share...


Syriphid Fly eating the nectar of a Calendula Flower.


Northern Leopard Frog, Rana Pipiens, this wet and soggy summer has been great for the frogs, never seen so many frogs and toads in the garden. Even found a young Wood Frog in the Zucchini. Plenty of bugs and slugs for them to eat this year.


Syriphid Fly tasting a Red Clover blossom. It's a great year for these Syriphid Flies too, there's dozens in the garden, the larva are predatious, often of aphids and other small soft bodied insects, but the adults are pure nectar eaters. And red clover is one sweet source of nectar. I use it as a natural sweetener in herbal teas.


Unidentified big green caterpillar.


Grass Skipper resting on the Betony blossoms.


Ichneumon wasp tasting the Carrot flower nectar, an important parasitoid in the gallery of natural enemies in the garden.


Marigold bloom.


Skullcap flower spikes. A hardy perennial herb useful to support a good night's sleep, and also a graceful flower in the garden landscape.


Grasshopper in the alfalfa. I've let my alfalfa bushes go to seed, after harvesting an early cut of leaves for herbal teas. The seeds for sprouting will be a great store of live food on our Winter menu. I just love the complement of colors in this image, the lavenders on the grasshopper highlighted by the alfalfa blossoms, the picture is a pallette of pastels.


The mullein flower stalks do not fail to attract the highest concentration of bumble bees, day after day. And the bees sure are stocking up on pollen from this prolific bloomer. Not only do they fill their leg pouches with rich golden pollen, but their fuzzy bums get covered in the stuff. Pollination in action.

04 August 2009

Meta-predator meta-narrative: The portrait of a lady

Lady beetles have been breeding like crazy in our garden this summer. It has been an education to observe their life cycle, from larva to adult, and it has been a pleasure to watch them flourish. I can only hope there are enough aphids in the garden to support them in their hundreds. We had a small window of about two weeks in the end of May when aphid infestations could be found in certain crops: in the wheat, quinoa and poppies primarily. But it didn't take long for the Lady Beetles to catch up.

Here is the life cycle of the Seven Spotted Lady Beetle, our most numerous species: Adult, lays eggs in favorable sites.

Larva, roams widely, preying primarily on aphids among other things.
Larva transforms into a pupa, and while attatching itself to a leaf, it does yoga exercises, stretching up to the sun, then down into resting position.

The pupa turn from yellow to this color patterning and stay put, about a week, before emerging as adults.

When pupation is complete, the beetle emerges...

yellow and tender as a newborn.

They seem to hang around the pupa casing until their shell begins to harden, trying out their newly acquired wings.

Just about the time they get their spots and start to turn from yellow to red, they abandon the dried casing, striking out into the garden for food.
Aphids on a wheat stalk.

The balance between predator and prey is never static, population densities are always changing, typically following a pattern of alternating boom and bust. In the biological study of ecological communities, it has been observed that when prey populations spike, it will trigger a population explosion of predators, who will typically over-extend the limits of their food resources. Prey species will dwindle, followed by dwindling predator numbers. It's like a game of tag, predator population density seeming to lag behind. As I've mentioned before, it is this lag time that we, as gardeners, must make up for, keeping pest populations under control until the predators can catch up, and either take over for our job, or more typically, complement our efforts to keep pests in balance. And even trickier a gardener must allow enough pest/prey species to survive in order to encourage and support the lagging predators, without letting pests get out of control, damaging the food crops and exponentially exploding in the next generation. It is this balance that I am learning, and observing as I watch the relationship between the aphids and the Lady beetles in my garden.

Recent biology studies into the relationship between predator and prey have revealed some counter-intuitive interactions. The first study I heard (on a radio science show) on this topic, looked into the re-introduction of wolves into parks where they had been locally eradicated for decades. It was thought previously, as it would seem by my description above of the cyclical tag game, that the predators in any given area were a result of the number and type of prey in that area, and that the prey were a result of the availability and abundance of forage. So it was surprising for biologists to discover that it is the predator who largely shapes the landscape, and not the other way around.

To summarize the study, in the absence of predators, the elk and deer had browsed un-harassed, and therefore had selected feed and feeding areas along waterways and streams, to the point where young willows and other trees were grazed down, and stream banks were beginning to erode, and in some places, even dry up. Without predators, the herds grazed the land in different patterns, effecting the landscape and the flora. When the wolves were re-introduced, herds had to return to grazing in open landscapes where they could remain watchful. They shied away from dense clusters of trees, and only approached more exposed waterways where they could stay alert to the ever present danger, minimizing the sites where they entered the water. In a matter of years, the willows regained the stream banks, held the erosion, and kept the waters cool and flowing for the fish and amphibians. Grassland, and meadows started to open again, and clusters of young trees were allowed to grow into forests, supporting the diversity of birds, each of which depend of a specific variance of habitat.

This first study into the impact of wolves on the ecological community from which they had previously been evicted, led to further studies into the impact of predators on the landscape. A study into the impact of spiders on the flora of pastures and meadows revealed the same counter-intuitive result: the presence of spiders changed the feeding habits of insects, which selected for certain plant species that would otherwise be grazed down by herbivorous insects. So perhaps we have the tag-game inverted, and should rather look at it as predators in the lead, with prey species fitting into the spaces where they can best survive, and the landscape as the result of this interaction.

It is interesting to think upon a gardener as a sort of meta-predator in the garden. The landscape, or garden, is the direct result of the gardener's selection of insects and varieties of plants. All other predators are there as guests and allies, dependent on the gardener for prey and habitat. I can see this type of relationship in my garden, never more so than when I hand-pick certain pest species. Patrolling the garden every day for Colorado Potato Beetles and larva, and Imported Cabbage Moth caterpillars, I feel very much like a predator. These are the two pests in my garden that are both visible and can be easily hand-picked, and both can do a lot of damage to foliage if left unchecked. And because I have daily observations of the pest populations, I am also able to observe the populations of predators, which leads me to learn more about enlisting and encouraging the specific predators. This kind of daily observation also teaches me a lot about the life cycles, and seasonal cycles, of these insects (or avian, amphibious and reptilian predators).

I sometimes see my job in the garden as Ecological Wildlife Management. I try to keep things in balance, using a variety of techniques such as row cover and physical barriers, but the most effective techniques are preventative and supportive. (I find the same is true for our own physical health as is true for the garden health.) Prevention techniques revolve around proper rotation, and often require it, for example, in my second year of gardening, I put row cover over a spring crop of radishes to protect from Flea Beetles, but had not managed my rotations correctly. Not yet understanding the life cycle of Flea Beetles, I quickly found that the first generation of Flea Beetles emerged from the soil, under the row cover. I have never yet used an insecticide, and will continue to view it as a last result. Insecticides, including the Organically acceptable plant derivatives, resemble anti-biotics in their inability to distinguish between harmful pests and beneficial insects. And insecticides work against any supportive measures to encourage an intact biosphere of beneficial predators and their prey.

A garden invites intimate interactions with the garden ecology. While reading a 1977 Organic Gardening and Farming magazine, I came across an article written by a woman who understood this intimate relationship. She had been handpicking Hornworm caterpillars from her tomato plants, and stomping them underfoot, when she came across a parasitized caterpillar. She left this one to hatch out the parasitic wasps inside, but was inspired to collect the rest of the caterpillars into a tall bucket. She left the bucket in the garden, and continued to collect and feed the pests. The parasitic wasps had access to an abundance of hosts, and it did not take long before she was hatching out dozens and then hundreds of beneficial wasps.

When I walk through the potato patch and find more Lady beetles and larvae than I can find Colorado Potato beetles, I look at that as the best crop insurance that money can't buy. The toads and Garter snakes have provided the same invaluable crop insurance against slugs in the market garden this year. With 20 inches of rain between June and July, our garden would be overrun with slugs if not for these hungry predators. And I am happy to report that Lady Beetles will continue to find other sources of food when the aphids run short, including the eggs of moths and other beetles, and small invertebrates, which may explain the dramatic reduction in hatching Colorado Potato Beetles since the Lady Beetle population has exploded. I am beginning to find them in the Brassica plot, hoping they will find the Imported Cabbage Moth eggs to be a tasty treat, between the occasional aphid meal.

28 July 2009

Busy as a bee

Been canning and harvesting for the market garden this week, so I'll leave you with some pictures from the garden.

Bumble bees are in abundance this summer, busy pollinating the garden. This one was snoozing in the Meadow Sweet, beauty rest.

Some of my favorite predators. We have had more aphids this year than normal, never to pest levels, but it has kept the Lady Beetles eating and breeding in the garden. We have about 4 distinct Lady Beetle species, and each look distinct in their larval stage as well.

I think this is the Seven-Spotted Lady Beetle larva, the commonly recognized red beetle with seven black spots.

The blooming of the carrot flowers always seem to hearald the first Tachinid flies of the season. Welcome.

And this is the first Green Lacewing I've seen in our garden, probably due to the attractive numbers of aphids this year.

Syrphid Fly, again in the carrot flowers. A welcome parasatoid.

We also have a family of Garter Snakes in the hay bale shelter, originally left for the toads. Still plenty of toads in the garden, but there was one particularly fat Garter Snake that probably didn't get fat on slugs alone. Hopefully the snakes don't get all the toads! Both the snakes and the toads have been keeping the numerous slugs in check this wet summer.

Our very own Fritillary visited our garden. Too bad it picked a rather ragged looking Cosmo flower for it's close-up shot.

The Hollyhocks are blooming, and were buzzing with Bumble Bees this morning.


As are the poppy flowers. Gorgeous to grow, and delicious seeds for the kitchen as well.

23 July 2009

Growing by degrees

The food cycle has finally reversed flow, there is more food coming into the house than we are able to eat... time to stock the pantry. Without a greenhouse, our stored food supplies need to last until the third week of July. It can be a struggle, and usually means relying on spring greens, grains, eggs and dairy for the better part of June and July after the last of the root crops and potatoes. And I always put away more than enough canned green beans to cover the gaps before those first glorious snow peas are ready in early July.

Although we planted each of these crops about three weeks earlier than last year, our first harvests are no more than a week to a few days earlier. I, of course, had my hopes up for a logical three-week-earlier harvest. But every season is unique. In doing some research, I happened across the phrase "Growing Degree Days". It is a unit used to measure or predict the first bloom or maturity of a crop, or the emergence of an insect or pest. Temperature is one of the most crucial elements in crop growth, and generally triggers most of the cycles of the insect world. And we have had an abnormally cool June and July. Especially July. Our nights have averaged at 10C (50F) instead of the normal 16-18C (60-65F). Only a few crops will continue to thrive with these nighttime lows, such as peas and Cole crops. Roots, onions and potatoes slowed down. And heat lovers: beans, tomatoes, peppers, squash and cucumbers just hung around, waiting.

Growing Degree Days can easily be calculated (go to the link above at Wikipedia), by keeping track of the maximum and minimum temperatures, which I have been doing for years, in my garden records. Each crop or insect has a cumulative requirement of heat, or Growing Degree Units to flower, reach maturity or hatch out. It will be interesting to use this unit in the future, to calculate and predict crop maturity or expected pest emergence, in an ever changing climate.


According to planting dates, we should have had our first new potatoes July 1st, instead of July 22nd, which shows that the cool weather set back the growing season by three weeks. Quite significant. But our first taste of potatoes, since the last wrinkled-ones in mid-June, was well worth the wait: Yukons, one large golden potato snuck out from each plant in a row. Boy they taste good. It's kind of a nice break, not eating potatoes in the gap between the last wrinkled, sprouting aliens, and the new, apple-crisp crop. Like cleaning the palette. After all, we do eat our share of potatoes over the winter. And come June we have an abundance of eggs so I can make all of the pasta I dreamed of making in the winter egg-drought.

Likewise, there is nothing like that first sun-warmed tomato... We savored, half each, on a bed of lettuce and snow peas, with a yogurt-dill-cilantro dressing.
Broccoli won't be far behind... I usually can't resist snapping off the first head and eating it right there in the garden.

The larger carrots can be selectively pulled from the row, making room and giving sunlight to the stragglers from replanting the gaps. I couldn't resist pulling a few early parsnips to go with the feast. The smell of freshly pulled parsnip roots and leaves reminds me of coconut. Didn't have any coconut milk in the house, but this is what the aroma inspired: carrots and parsnips sliced, steamed, cooked in butter, with chopped mint, peppermint and finely chopped dates. New favorite.


Our last carrot planting was later than usual, after the cutworms marched through, taking two May re-plantings with them, I was too discouraged to plant again, until after we put the cutworm fence around the fallowed, cutworm free plot. The first week of July started with a flood and ended with a drought, I planted the carrots between 1" rains, and then the weather turned hot and dry, forming a crust on the surface of the soil. Larger seeds would not be worried by this, but tender carrot seedlings can really struggle with obstructions. And the heat was to continue for a week, so I experimented with laying a fine layer of hay over the beds, aiming for 50% coverage, like shade-cloth, to bring the soil moisture back to the surface and soften the soil, allowing the seeds easy emergence.

It worked beautifully, the carrots poked up between the mulch, and it has worked to suppress some of the early weeds. As the crop emerges, I gently part the mulch and concentrate it between the rows to further suppress weeds.

13 July 2009

Blooming

I do love vegetable flowers, and watching them unfold gives me more than an aesthetic satisfaction because the edible fruits are soon to follow.

We have potato flowers in varying shades from white to pink to lavender to blue, depending on the variety and corresponding with the color of the potato skin. As soon as these flowers begin to die back, I can begin to excavate some of the treasure trove beneath.
Pea flowers are short lived and delicate creatures. This time of year, the pods seem to grow by inches straight out of the newly opened blossoms.
Bean flowers remind me of orchids, perhaps the homely cousin, but beautiful still. And they continue to flower as young bean pods form, promising a reliable harvest, enough to put away for winter.

Pumpkin and squash flowers glow like lanterns in the bare spring garden, and not surprisingly, they never fail to attract interesting insects for nectar, prey or shelter.

Some flowers are a harvest in themselves, brightening and enlivening salads or garnishing meals. These Nasturtiums have a nearly addictive peppery tang.

And some vegetable flower are only ever seen in the seed saving garden. This globe of tiny onion flowers is wrapped in paper like the bulb below.
But for pure show, no vegetable flower can compete with the infinite variety of plants, bred and shared generation after generation, for the simple delight and surprising complexity of it's flower. Marigolds, Cosmos, Calendula and Hollyhocks have found gaps and corners in our vegetable garden, my selection based on their hardiness and ease of growing.

But nothing brings more insects to the garden than the homely flowers of dill, cilantro, caraway and carrot.

06 July 2009

On Safari

After one entire week without a single ray of sun, we breathed a deep sigh of relief and exhilaration when the clouds and heavy fog finally broke this morning. I could just feel the plants growing, the robins and wood thrushes broke into a loud chorus, and my downcast mood was instantaneously replaced by the same chatter and activity as the birds and the bees. What a difference a little sunshine makes!

And just in time too, the peas were beginning to rot at the tips, due to water-logged roots, the first crop to show water stress in our garden.

Not much has been going on in the garden these last few weeks, with little to weed and even less to harvest, I've been going on safari. We walk the garden every day, to watch for signs of insect damage or disease. This is often done in the course of harvesting ripened produce and weeding, but I also keep a close eye on insect diversity, dispersal and populations in the garden as a part of my own experiment on how well beneficial insects are able to control pest insect numbers.

And it's a jungle out there. I have found a number of new and interesting critters, along with familiar allies. And for some reason or another, the most biologically diverse and productive area of the garden has been in the potato patch. I suspect it is the universal allure of the plump and slow-moving Colorado Potato Beetle larvae. The always remind me of the insect world's equivalent of a herd of grazing cows, and what wolf or coyote can resist?

We handpick the adult beetles (from 5-20 a day), and squish the little larvae when we see them, but surprisingly few larvae are either hatching or growing very large due to the numerous predators.
Including this Harvestman (or Daddy Longlegs), they are general predators and scavengers. I think he had his eyes on that plump potato beetle larva through the foliage in the distance.


Even the eggs are being eaten by something or other, it's hard to know who... they do look pretty tasty.

It could be these Long-Legged Flies, numerous in the potato patch, they will eat both eggs and beetle larvae.

Another friend, spotted often resting in the dense foliage of the potato patch, this Slug-Killing Fly or Marsh Fly (of the Tetanocera family). They are parasites of slugs and snails, of which there are plenty due to the wet spring. Adults lay their eggs on slugs and snails, and feed on nectar or pollen, offered by the blooming potato flowers.


Another predator found hunting the potato jungle, an Ichneumonoid Wasp. This rather homely specimen does not compare to the more graceful and colorful Braconid Wasp spotted in the garden, and too elusive to photograph.

Outside of the potato patch, carrot flowers never fail to attract allies. The metallic and pastel shades of this Predatory Stink Bug or Spined Soldier Bug contrast well with the budding carrot flower, rather pretty isn't it? Not only pretty, but a very good ally in the garden, with an appetite for some of the most discouraging pests. "Over 100 species in many families have been reported as prey. Prime targets are immature insects. Reported prey include the larvae of Mexican bean beetle, European corn borer, diamondback moth, corn earworm, beet armyworm, fall armyworm, cabbage looper, imported cabbageworm, Colorado potato beetle, velvetbean caterpillar, and flea beetles."

Everyone loves a Lady Beetle. Even those who are squeamish about bugs cannot find much fault with this Seven-Spotted Lady Beetle. It's probably the absence of any creepy looking legs, antennae, stingers, proboscis, spines or slime that win the hearts of every gardener. We don't have many aphids in our garden, but there's always a Lady Beetle or two around. Mostly these and the Three-Banded Lady Beetle.

Scavenging the ground level of the garden, I can hardly disturb the soil without finding one of these hard-working Ground Beetles. This is the largest, and earliest emerging Ground Beetle species in our garden. But it has been accompanied by two or three other species, including a smaller bronze colored one, and a smaller plain black one.

And this iridescent species. This picture shows off their mouth parts, wouldn't want to be a soft-bodied insect in their way. They have been doing very well this year, feeding on the abundance of cutworms in the soil. I often disturb one dining on a grub, and in one heavily infested bed, where I found 100 cutworms, I disturbed about 25 Ground Beetles. Not a bad predator to prey ratio.

Also numerous and widespread are these mother Wolf Spiders. They are general scavengers, will catch prey or eat insect eggs in the soil, including Grasshopper eggs. From what I've read, dozens of little bitty-spiders will emerge from these egg sacs, and the mother spider will continue to carry them around on her back until they are large enough to fend for themselves. I find about one of these sack-toting mothers about every 100 square foot of garden, so there will likely be hundreds of hungry teenage spiders, scavenging the garden soil this summer.

Another maternal insect, the White-Margined Burrowing Bug. She is not a predator, but caught my attention with the dozen or so nymphs riding around on her back. They are related to the Stink Bug (or True Bug), but burrow in the ground instead of staying in the canopy like their cousins. And they verge on the pest side, as sap suckers, or root eaters, but are not known as a major pest.
And for a finale, the strangest critter found in the garden this spring: Strauzia longipennis, the Sunflower Maggot Fly. Entomologists must have a sense of humor. *giggle* Not surprisingly, it was found on the sunflowers, laying eggs on the undersides of the leaves. The eggs will develop into maggots, eating leaves or seeds, depending on the species. Until I hunted down the identification of this particular insect, I was unaware that sunflowers had a specific pest (besides Blue Jays), so I will be watching for any maggots or leaf damage on my sunflowers.

I hope you have enjoyed this safari tour of hunters and hunted in the garden. Keep prowling around in your own.

Overall, I am each year, impressed with the diversity and population of predators, scavengers and parasites in our garden. And to encourage their cooperation I have been researching their specific life cycles, food and overwintering needs. I have found that all the information I need can be searched on the net, but it is not compiled, all on one site, that I can continue to refer back to when needed. So I am keeping the information I collect on two spreadsheets, one for beneficials and one for pests, specific to my own garden bio-diversity. I am sure they will prove to be handy reference charts while planning, rotating, planting and cultivating the garden.

Included in the pest chart I have a column for each of the following: Taxonomic Family name, Visible Crop Damage, Feeds on as larva, Feeds on as adult, Natural Enemies, Hosts On, Life Cycle, Overwinters As, Control Methods. The beneficials chart includes columns for each of the following: Taxonomic Family name, Feeds on as larva, Feeds on as adult, Hosts On, Life Cycle, Overwinters As, Attracted or Maintained by. In these charts I list my own experiences with controlling or attracting insects, as well as methods established by generations of gardeners. You may find this a helpful tool in your own garden.