Milkweed Catches Moth

In my last post I explained that milkweed pollination depended on an insect, or other flower visiting animal, snagging a pollen cluster, called a pollinium, from one flower and moving it to another flower.  Insects catch their legs on the thickened terminus of two pollinia bearing tethers and pull the pollen body from a slit in the flower.  The process is often a failure for both the flower and the pollinator.

This is a beautiful Reversed Haploa Moth.  I rarely get the opportunity to take my time photographing winged subjects before they disappear, but his moth wasn’t about to leave its perch.

I was originally attracted to the location by a frantically gyrating moth.  This often indicates that a pradator has grabbed hold and is trying to subdue its prey. 

Following a bout of fluttering, the moth would hang motionless from the flower.  A close examination of the situation showed no predator in evidence.  It appeared that one of the moth’s legs was caught by the milkweed flower.

This was exactly the case.  In the process of pulling free a pair of pollinia, the moth’s foot either caught on the pollinia tether or was directly caught in the flower slit.  The moth did not have the strength necessary to pull itself free.  This is a fairly common scenario that usually ends with the insect dying on the flower, or more typically, falling easy prey to some predator.

After capturing a few of the interesting poses presented by the moth, I pulled its leg loose from the trap and set it free. 

A short video for those who may never have witnessed the frantic gyrations of a trapped moth.  That foot must be really struck to hold fast against all of that exertion.

Monarch Butterflies

The spring Monarch Butterfly migration passed without a single Monarch sighting at Blue Jay Barrens.  My earlier disappointment has been abated with a summer season Monarch count surpassing any in recent years.  The Milkweed stands are receiving frequent visitations from this colorful butterfly.

Of course, this is the real reason for maintaining patches of Milkweed plants.  Monarch larvae are Milkweed eaters.  Recent declines in the Monarch population make it more important than ever that this plant be readily available.

Having Milkweed plants snug up against the house makes it easy to monitor the progress of leaf eating insect larvae.  Because of a beating they took during a spring thunderstorm, a few of the plants are unable to maintain an upright position.  Most, however, are standing tall, even though a few needed some propping up and stem support to achieve this condition.

Landscape designers probably wouldn’t recommend crowding the entrance to your home with seven foot tall Milkweed plants.  I would agree, especially when the flower visiting bees during the day or moths at night get sucked into your home every time you open the door.  This Milkweed thicket was not actually intentional.  A single plant that became established beside the water garden was allowed to remain.  Within a couple of years that one plant became two dozen.  For the benefit of the Monarchs, I let them remain.  I must admit that I am also fascinated by the vast array of insects attracted by these plants.

I’m currently finding larvae of all ages.  The youngest are just beginning to show their characteristic black filaments.  Small larvae are easiest to see by looking from below a sunlit leaf. 
 

Midsized larvae show short stubs where the long black filaments will eventually be.  Larvae can also be located by examining holes in the leaves.  Feeding sites are more regular in appearance than hail damage left by the early storm.

Leaf damage causes the Milkweed plant to ooze its thick white sap.  The sticky sap can make it difficult for the larva to feed.  The larva overcomes this obstacle by systematically severing the veins leading to the leaf, this stopping the flow of sap.

In small leaves, the midrib is often cut to halt sap flow to the entire leaf.  On larger leaves, a series of lateral veins might be cut as seen here.

Once the sap stops flowing, eating commences.

The larvae seem to practice an eat-and-run technique that minimizes time spent in any one location.  A section of leaf is consumed and then the larva moves on to another location.  Many predators are attracted to leaf damage in search of prey.  Despite the Monarch’s unpalatability due to accumulating toxins from the Milkweed plant, some predators have to learn the lesson first hand to the detriment of the larva.  Even though they are bad to eat, the best survival strategy is to avoid the predators.

The excess rainfall experienced this spring has really benefited the Milkweeds in the field.  The plants bloomed early and are continuing to produce new flower buds.

This large stand of Purple Milkweed continues to attract Monarch Butterflies as well as other insects dependent on the Milkweed plant for their survival.

It appears that Blue Jay Barrens will contribute a large number of Monarchs to the masses that will make their way south later this summer.  I just hope that conditions at their wintering grounds are favorable for the species continued survival.

Uncontrollable

When managing land for biological systems, there are many factors over which you have no control.  Some of these have an enormous influence over your success.  A prime example is the weather.  Yesterday evening, Blue Jay Barrens was visited by a thunderstorm exhibiting high wind, heavy rain and hail.  Physical evidence of the storm’s passing was abundant.  Downed tree limbs, broken plant stalks and flooding were found everywhere.  What I observed from the relative safety of the front porch, was the toppling of the milkweeds.  It all began with the simultaneous arrival of howling straight line winds and a heavy downpour of rain that sent an impressive wave of water spray breaking over the eves.

Wind and rain subsided slightly as a flurry of hailstones joined the mix.

Milkweeds near the water garden, heavy with rain and battered by hail, began to give way before the wind.

As the hail thinned, rain increased in intensity.  Several milkweeds have remained upright.  At this point, I was thinking the worst of the storm had passed.

I was wrong.  Heavy rain continued, hail resumed and the wind returned with a roar loud enough to send me running to the other side of the house to see if anything dangerous was headed in my direction.  When I returned to the porch 20 seconds later, the wind was driving straight down and pushing spray into the porch and onto the ceiling.

We went from hurricane like conditions to a light summer shower in just a few seconds.  I watched the back end of the storm thrash the woods on the hill across the road and then it was gone.  Amazingly, some milkweeds are still standing.

Violent summer weather may be uncontrollable, but that doesn’t mean it’s unpredictable or unexpected.  The milkweeds around the water garden, as well as many out in the fields, get flattened every year.  Younger specimens can almost bring themselves back upright after a storm, while those at this stage will gradually reorient the top of the plant so the flowers are held up for insect visitors.  Their susceptibility to storm damage does not diminish their importance as a valuable part of the natural ecosystem.

The milkweed stalks have not broken at the base and can be returned to an upright position if stakes are provided for support.  Since these are growing right outside the front door, I’ll do my best to return them to their proper orientation.  My wife claims that they remind her of Triffids lurking in wait near the porch and I don’t want them to appear as though they are reaching out to her.

The leaves will carry their hail damage for the rest of the season.  The milkweeds colonized the water garden flower beds on their own several years ago.  I left them alone to grow and increase their numbers because this patch seemed to be a preferred egg laying site of the Monarch butterfly.  Monarch caterpillars have always been present on these plants by this date in past years and evidence of their feeding should be present on the leaves right along with the hail damage.  This year I have yet to see my first Monarch.  Plenty of other insects utilize the milkweed, but it just doesn’t seem right without the Monarchs.

Milkweed

Milkweeds are champions at attracting a wide variety of insect species. There are the casual visitors that come to the plant just for food, as well as an entire menagerie of species that are intimately tied to milkweeds for their survival. When out walking, I always check the milkweeds to see what animal life can be found. A variety of tiny flies were visiting this bloom.

Common Milkweed, Asclepias syriaca, is a plant of the open fields. Many people tell me that milkweeds growing in the field are a sign of mismanagement. It seems to confuse them when I suggest that the presence of milkweeds only signifies poor management if you are managing for a condition that doesn’t include milkweeds. Milkweeds in a pasture or hay field indicate poor management, but milkweeds in a field being managed for diverse native grassland species do not, so don’t use that as an argument that I’m not caring for my fields. This is the point at which I turn the conversation towards the weather, which my daughter says is the only subject I’m capable of handling in social situations.

The fully opened milkweed blossom is a nectar factory that feeds a multitude of different species. I’m especially interested in pollinators and spend a lot of time watching the native bees. A few weeks ago I was with some backyard fruit growers who were lamenting the decline of the European Honeybee and wondering how their flowers would be pollinated if things didn’t improve. When I suggested they try managing for native bees that could provide the same pollination service, they looked at me as if my hair had caught fire. Apparently, any acceptable substitute had to share the honeybee’s ability to work on demand as well as produce a marketable byproduct.

This grasshopper is eating a portion of the flower. Milkweeds contain steroid glycosides and other toxic substances that make the plant unpalatable to all but a few species that have evolved to deal with the toxins. The concentrations of toxins vary throughout the plant, so the grasshopper may be feeding in a less dangerous area. The tiny white spot on the grasshopper’s back is the empty skin of a tachinid fly egg. The larva has recently hatched and made its way inside the grasshopper, where it will feed until ready to pupate. The grasshopper will not survive the activities of this parasite. Perhaps milkweed toxin is a remedy to tachinid fly infestation.

The flowers are even attractive pre-bloom. Like many plants with multiple blooms, the flowers develop and open in succession, so the blooming and pollination activities occur over a long period.

The underside of the Common Milkweed leaf reminds me of a thick carpet. You certainly wouldn’t imagine these tough, hairy, poisonous leaves to be something edible. I wonder what was after these plants that made them evolve such a collection of defensive mechanisms.