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.

Common Milkweed

Common Milkweed is now in full bloom at Blue Jay Barrens.  Common Milkweed has a strong network of rhizomes that allow a single stalk to become many in a short amount of time.  Milkweeds have just about surrounded the Water Garden this year.  I had to remove some stalks from the driveway and a couple more that were threatening to block access to the front porch, but there are still plenty left for the Monarch butterflies and other animals.

Milkweeds form a mass of flowers whose stalks all originate from the same point, a form known as an umbel. The large number of flowers found in each umbel typically cause the umbel to appear in the form of a sphere.

The petals fold back to reveal a central column of reproductive parts which is surrounded by a set of five two-part structures known as the hood and horn.  This arrangement has always reminded me of the old dental spit-sink with a hooked claw emerging from the drain.

Milkweeds do not produce the dust like pollen common in many flowers. To affect pollination, an insect carries a pollen mass, known as a pollinium, from one flower to another. A knot like affair joins two pollinia by short threads.  The insect’s foot or leg catches the thread and pulls the pollinia from a slit between the hoods. The photo above shows the location of the slit with pollinia still intact. Above that is a pair of pollinia that have been removed from the flower. I guess a flower needs to attract a wide range of insect visitors when pollination requires an incidental snagging of a pollen mass followed by the proper placement of that pollen mass on a new flower.

Milkweed flowers attract a wide range of bee species, from large…

… to small.

Some insects are attracted to the milkweed plant not by the flowers, but by other flower visitors. This is a Conopid fly.  Conopid larvae are parasitic on bumblebees. The Conopid adult will attack a bumblebee in the air, force apart two abdominal segments, and lay an egg in the abdomen of the bumblebee. The larva consumes the bumblebee from within over the course of a couple of weeks. The action of this parasitic consumption causes the bumblebee to dig a hole and bury itself before dying, providing the Conopid larva with shelter in which to pupate and overwinter.

Like many other insects, the Conopid Fly uses mimicry to help avoid predation. In this case the fly looks suspiciously like a wasp.  Would-be predators, fearful of a stinging response, are more likely to pass this fly by.  The easy way to tell the difference between a fly and a wasp is to count the wings. A wasp has two pairs of wings, while a fly only has a single pair. In lieu of the second pair of wings found on bees and wasps, a fly has a pair of structures known as halteres.  Halteres help to balance the fly in-flight. In the photo above, the two white objects at the rear of the thorax are the halteres.

Highly colorful Long-legged Flies flit about the leaf surfaces of many plants. The large milkweed leaves seem to particularly attract this insect.

It wouldn’t be a milkweed plant without Milkweed Bugs. Milkweed Bug pairs are often in mating tandem at this time of year. The reproductive process is not going to stop the upper bug from probing the milkweed flowers for a meal. The lower bugs is dragging around a pair of pollinia on its middle foot. The pollinia will be wasted if not deposited into an open flower.

Goldenrod Soldier Beetles are also busy with courtship rituals. These beetles are pollen eaters and will visit many species of flowers besides their namesake Goldenrods.

The milkweed flowers are brightly colored, strongly scented producers of abundant nectar. Most moth visitors appear after dark and are rarely noticed.  The Hummingbird Clearwing is one of the few brightly colored moths that visit the flowers during the daytime.

Many species of skippers are attracted to milkweed. This is the Silver-spotted Skipper, one of the largest and most easily recognized of that group.

Butterflies of all sizes visit milkweed. On the smaller end of the scale are the tiny hairstreaks, like this attractively marked Banded Hairstreak.

Great Spangled Fritillary butterflies have been mobbing some of the milkweed flowers. If your interest is in viewing butterflies, and other interesting animals, it’s worth encouraging a few Common Milkweed plants to live somewhere near your house.

Still photos don’t do justice to mobbing butterflies, so I offer the short video above.

Common Milkweed Activity

I’ve been admiring some of the Common Milkweed plants that have put on luxuriant growth despite the super dry conditions.  This one has topped out at about seven feet.

Most plants are carrying six or eight seed pods.  Tendrils on the surface of the Common Milkweed seed pod present an alien appearance.

It looks like it’ll be a bumper year for Milkweed seeds.  All of the pods are large and full.  It won’t be long before the seam separates to release the ripe seeds.

Monarch butterflies are around loading the plants down with eggs.  I watched this female lay 17 eggs on a clump of three milkweed plants.

It may be warm now, but this egg is in a race to produce a mature butterfly before cold weather arrives.  Monarchs will not survive an Ohio winter.  In order to survive, the mature butterfly will have to emerge and make its long migratory journey to the south.

The Monarch is not the only insect depositing its eggs on the Milkweed leaves.  These orange gems were left by a female Milkweed Bug.

Here’s the likely source of those eggs.  This is an adult Small Milkweed Bug, a species that specializes on eating milkweed seeds that are still held within the pod.

The nymphs form colonies on the milkweed plants.  They are most likely to be found congregating on the seed pods where they use long, tube-like mouthparts to probe deep into the pod to access the hidden seeds.

The nymphs will shed their skins several times before emerging as an adult.  To avoid being damaged during this vulnerable time of their lives, the little bugs will move away from the pack and pick a secluded spot in which to shed.  After a while, shed skins can be found just about anywhere on the plant.  The variety of interesting activities occurring on milkweeds makes the cultivation of this plant a rewarding endeavor.

Milkweed and Monarch

Judging by the numbers of larvae currently present, Monarch butterflies are going to be particularly abundant this summer.  Strong southerly winds and warm temperatures brought this migratory butterfly to Blue Jay Barrens much earlier than normal.  I’m looking forward to having this species as company through the summer.

The Monarch butterfly was partly responsible for what people referred to as my poor attitude towards school.  In our fifth grade science text, the developmental stages of a butterfly from egg to adult were exclusively portrayed by the Monarch butterfly.  When the teacher distributed drawing paper and asked us to draw those stages, the entire class reproduced the illustration of the Monarch.  Except for me.  I chose to illustrate a Black Swallowtail, a species that I had raised on Wild Carrot during the summer.  The teacher used the text illustrations to show how inaccurate my drawing was and explained that what I portrayed could not exist.  I decided that if she could be that wrong about butterflies, she was probably just as wrong about everything else she was telling us, so I stopped listening to her. 

Monarch caterpillars feed on Milkweed leaves.  A single Common Milkweed sprouted near the Water Garden a few years ago and has since developed into a nice clump.  I see it every day, so it’s easy keep track of any changes.

Fras accumulation on the leaves told me that there were caterpillars at work. 

Fras is also known as caterpillar poop.  Caterpillars spend their lives taking in plant material and expelling waste.  In a search for caterpillars, it’s often easier to find the fras and then trace that back to the animal.

Loss of plant parts is another indicator of caterpillars at work.  Newly hatched caterpillars often have trouble eating mature leaves.  Newly formed leaves, like those found sprouting from the leaf base, are much easier to consume.  A missing sprout is often caterpillar sign.

Holes or missing sections of leaf can also be the work of caterpillars.

Just looking on the other side of the leaf reveals the culprit.

The pattern of feeding is often a deliberate attempt to stop sap flow into the portion of leaf being consumed.  A damaged Milkweed leaf often releases the sticky sap.  By isolating a section of leaf, the caterpillar can feed undisturbed by the sap.

Not all holes in a leaf represent feeding damage.  Jagged tears or holes, especially those with ragged bits of leaf remaining, are examples of physical damage.  In this case, the leaves were battered by a hail storm.

Flowers are also a choice target for smaller larvae.  Some species of moths and butterflies actually lay their eggs on the flower buds. The young can begin feeding on more delicate parts before moving onto the tougher leaves.

Many insects avoid detection by remaining on the under side of leaves, so always get your head down and look up.  I watch many people examine a plant by staring at it as though it was a picture.  Plants are three dimensional objects that require examination from various angles.  Don’t forget that our bodies are supposed to twist and turn.  Use that ability to avoid missing some of the wonderful things in nature.

Common Milkweed Creatures

I began the week with a look at various animals on one type of milkweed, so I thought it appropriate to finish the week with a look at creatures inhabiting another type of milkweed. Common Milkweed is widespread, but it seems to prefer soils towards the moderate to wet end of the moisture scale. The flowers usually don’t form the dense cluster typical of other milkweed species and their tendency to droop detracts from the visual effect. It’s still a powerful attractor of insects and other small creatures.

Continuing with the black and orange theme of milkweed dependent insects is a pair of Milkweed Beetles.

It seemed to be a time of interaction for the creatures of the milkweed plant. These Milkweed Beetles are doing their best to ensure a future supply of beetles. In fact, I didn’t find any single beetles on any of the plants I visited.

Ambush Bugs were also busy starting a new generation. Mating insects are a little slower to move to cover when disturbed, so make good photographic subjects.

The flower clusters were full of small beetles and showed many signs of feeding damage.

Where ever insects congregate, you’ll find predators. That’s certainly an impressive set of spiny legs. I wonder if the spines serve as some sort of sensory device.

There was also a lot of interaction between different species. The beetle fled a flower cluster as I was pushing the plant around to get a good picture. The spider was quick to take advantage of the opportunity.

I’ve pretty much learned what to expect when I see a butterfly acting strangely on a flower. Edwards’ Hairstreaks move about almost constantly when nectaring. If you see one holding still, you know there’s something wrong.

Just as I suspected, a crab spider. This sort of activity goes on all the time, but I hate to see the rare things being killed. I hope it took care of mating and egg laying before it came over and got itself eaten.