Hey Neighbor, Can I Borrow a Cup of Milk . . . Weed?

            This year I have a bumper crop of monarch caterpillars.  Every milkweed plant is covered with them, and they are consuming all of my milkweed.  There are few leaves left on any of the plants and some have been stripped of all leaves and flowers.  The biggest caterpillars are eating the stems and even the seed pods, but the younger ones need leaves.  Each time I find a chrysalis, I think, “good, one less mouth to feed!”  Finally, I began calling neighbors asking if I could romp through their fields in search of milkweed.  I found a small patch in one neighbor’s field that hadn’t been mowed.  I cut one large stalk of the common milkweed, put it in water, and transferred a few caterpillars onto it.  Tomorrow I will cut another stem. 

           I thought I planted plenty but now I feel like a poor mother with too many mouths to feed and not enough food to go around. Adult butterflies only drink nectar from flowers, but caterpillars are eating machines.  As they eat and grow, they shed their skin about five times during the larval stage.  The time in between shedding is called an instar. 

           Actually, seeing lots of monarch caterpillars is good news because in the past 20 years the monarch population has decreased an estimated 90 percent. There are many reasons, including deforestation where they winter in Mexico, and loss of habitat, especially in the midwestern corn belt and wheat belt.   

           Survival is difficult but I am hopeful that some of my caterpillars will become the adult butterflies that will make it all the way to Mexico. 

Monarch Life Cycle

Egg – 3 or 4 days.  Monarch butterflies are host specific, laying their eggs only on milkweed plants.  A female can lay several hundred eggs in her short lifetime.

Larva/Caterpillar – 10 to 14 days. 

Pupa/Chrysalis – 10 to 14 days.

Adult/Butterfly – 2 to 5 weeks. The last generation that emerges at the end of summer will live 8 to 9 months and migrate to Mexico.



Competition is tough.

 

 

 

 

 

Older caterpillars are reduced to eating stems.

 

 

 

 

 

 

 

 

Some are even eating tough seed pods.

 

 

 

 

 

Next they pupate.

 

 

 

 

The chrysalis darkens before it is time for the butterfly to emerge.

 

 

 

 

Monarch Caterpillars -- At Last!

         

           I finally spotted a monarch in my yard about a week ago.  After disappointingly spotting a few viceroys several weeks earlier, I have been looking diligently for monarchs, and finally saw a female nectaring in my garden.  Both swamp milkweed (Asclepias incarnata) and blood flower milkweed (Asclepias curassavica) were nearby.  The monarch's wings were a bit ragged and her coloration was faded.  Adults only live a few weeks.  As I watched, she visited the milkweed, but not the flowers.  Instead, she landed on the leaves on the lower part of the plant. Butterflies can taste with their feet so  I suspected she was searcing for a place to lay eggs and today I discovered caterpillars!  I counted 5 caterpillars in various sizes and instars.

          Finding caterpillars prompted me to examing other milkweed plants around my yard and meadow, where I found several more caterpillars.   Naturally I also found lots of orange-colored aphids feeding on  the plants.  I squished as many as I could with my hands, wearing gardening gloves of course.  Aphids suck the juice out of the milkweed that the caterpillars need for food.  Monarchs only lay their eggs on milkweed, which is the sole food source for the caterpillars. 

          Milkweed contains toxins -- cardenolides.  Insects that eat the toxic milkweed taste bad to predators.  Although adult monarchs don't eat the plant, they still carry the toxins from the caterpillar stage to the adult stage.  The orange and black coloration of adult monarchs  is a warning sign to predators. 

          Milkweed plants support of lot of life.  I found several insects and butterflies nectaring on milkweed flowers.  More of the blood flower milkweeds are currently flowering right now than the swamp milkweeds.  Both varieties have produced seed pods already.  With seed pods, naturally I found milkweed beetles that feed on the pods as well as the plant.  There isn't much I'm willing to do about them.  They are too big for me to squish, and of course I can't spray insecticide on milkweed that the caterpillars are eating. 

          I have been monitoring milkweed pods in order to harvest seeds to plant next year.  The best way to do this is to check the pods regularly.  As soon as one splits a tiny bit, I know the seeds are ready to harvest.  If the pod opens fully, it is difficult to separate the seeds from the fluff that carries them through the air.  That fluff was once used in early flotation devices.  By opening the split pod further, I can hold one end of the white part where the fluff is still attached and simply scrape off the seeds, leaving the fluff intact and collecting clean seeds. 






A female monarch investigates a milkweed plant.



A monarch caterpillar feeding on milkweed.



Orange aphids feeding on milkweed.



Milkweed beetles feeding on seed pods.



Many butterflies sip nectar from milkweed.



A variety of insects nectar on milkweed.



A seed pod partially opened.



It is easier to harvest seeds if the pods aren't fully open.



The white fluff remains intacts, making seed collection easy.



    






In Pursuit of Bugs

                  It was a perfect summer day when Entomologist and  County Extension Agent Dan Nortman led master naturalists on an insect survey in Powhatan.  Finding the most insects, and the most diverse insects, requires two things -- sunlight and native plants, Nortman explained.  Participants learned several methods for collecting insects.  Gently beating a low oak branch over a white sheet produced several specimens for the group to examine.  Insects captured were temporarily placed in plastic containers for a closer examination after the walk.

                Participants used sweep nets to collect insects from a sunny meadow.  This effort produced mayflies, ladybugs, bee mimics, leaf beetles, a few native bees, katydids, a bronze borer, soldier beetles and immature praying mantids.  Nortman uncovered a small froghopper nymph beneath its frothy spittlebug juice.

                Along one trail Nortman pointed out traces of leaf miner insects.  A larval insect crawls between the top and bottom layers of a leaf.  As the insect grows the trail on the leaf grows bigger.  It pupates inside the leaf and exits as a mature insect.  The plant may appear unsightly, but the insect doesn’t cause any harm.  Leaf miners may be moths, sawflies, flies or wasps. 

                We stopped at a creek and several members of the group collected macro invertebrates from the water.   Besides stirring up a few salamanders and crayfish, we were able to capture and examine stonefly and dragonfly larvae.

                Other interesting specimens were collected during the day.  One daring participant captured a wolf spider carrying dozens of its young on its back. Tiger beetles were spotted but evaded capture.  Rotted logs provided another source of insects for collection. All of the captured insects were released after examination.

                For those who interested in insect identification, Nortman recommended Kaufman Field Guide to Insects of North America. 

Using sweep nets to capture insects.

Transferring the catch into plastic containers.

A stonefly naiad with wing buds (left) and a mature stonefly with wings (right).