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Tuesday 28 August 2012

Metallic Blue, Spreading Dogbane and a Handsome Moth.




Milkweed Beetles, Spreading Dogbane and a Handsome Moth.


One year ago I came upon a large field of pretty plants with bright green foliage and clusters of gentle white and pink bells. Upon closer examination I discovered hundreds, if not thousands, of tiny metallic-blue beetles crawling over their soft leaves and over the reddish stems. Here and there were droplets of white sap oozing from the plants tissues. The plants were interesting but my attention was drawn to the oval cobalt blue jewels.  They were Milkweed Leaf Beetles  (Chrysochus cobaltinus ) . They were in serious mating mood, the females trying to attract the best of the best, the males trying to outfight and outsmart each other for the right to procreate. Those who made it still clutched their females for quite a while after the fact, apparently making sure that their precious sperm cells had enough time to reach the eggs inside. The females of this species are polyandrous and if another suitor managed to deliver his cargo too soon after the first one, his cells could outrace the previous ones and pass the second guy’s genes to the next generation.

Obviously, it is not easy to be a beetle these days.


Those who did not mate resorted to grazing, what else? Any time my lens got too close to the beetles, single or tandem, they would simply drop to the shaded ground, their metallic shine disappearing with the lack of light. Shiny-blue rain of tiny armoured bodies.

When handled, these beetles were anything but cute – they stank, and though I did not try, they were probably quite unpalatable (to birds and other predators as well). The reason? Most likely their diet since both, larvae and adults feed on the sap laden foliage. Apparently the milkweed beetles lay their eggs on the leaves of this remarkable plant. Caterpillars consume the leaf tissues to a great extend and later pupate in the soil underneath. Yucky tasting in every stage! Who could think of better protection.


I had so much fun with these beetles that I totally forgot about the rest of their environment. Only at home – far away from the place where I took my photos, I realized that I paid no attention to the pretty plants.



  
The herbaceous perennial occupied by the Milkweed Leaf Beetles that day goes by a sinister but well deserved name - Spreading Dogbane (Apocynum androsaemifolium). Its delicate white and pink flowers appear in June and last until about September.

Do not be fooled by the outer appearance though. Dogbane produces nasty toxins that might not bother the beetles or other invertebrates; on the contrary, it is beneficial to the insects by providing them with nasty taste that protects them from being eaten by birds and small mammals. (What in this relationship is there for the plant - if anything - is beyond me.)

No such luck for mammals! 
Dogbane sap is a powerful cocktail of glycosides that can cause cardiac arrest, respiratory, kidney and other problems in browsing animals and livestock. What a great protection against being eaten by the big guys! 

Spreading Dogbane used to be used by Native peoples for a variety of medical treatments – needless to say that in our times such activities should be left to research and medical profession since Dogbane could cause serious sickness and death in humans. Even touching the plant could make skin to blister although most people do not react to it this way.
The sap had been used to kill unwanted dogs and other animals. Thus the common name.

It has also been used for other than medicinal purposes. Just like Flax , Spreading Dogbane and its relatives posses long and strong fibers that could be used to make rope, fishing nets or even thread and cloth. Check out YouTube if you want to learn how.

While I was learning all this about Spreading Dogbane a hairy but beautiful caterpillar made its way into my world. It was the end of August when I found it one early morning, hiding underneath a juicy sunflower leaf in our yard. Soon after there were more and my ID search revealed a possibility that this could be the baby stage of a handsome Dogbane Tiger Moth. - Cycnia tenera.


The Dogbane Moth's caterpillars feed at night, preferably on Dogbane but also on other species that contain milky sap such as milkweed (Asclepias spp.). plenty of that around here.
No bright colours needed when active at night? I wonder what this guy looks like under the black light....?

The adults fly at night but also during the day and they are not known to be well liked by the birds. They too, might be using the toxic sap for protection. Who ever said that the insects are simple creatures?

Although this guy managed to escape we found two more crawling about the garden today.
They are now being fed in a makeshift terrarium – just wondering if we can have them pupate and see the adults come out at the end.

That would be the ultimate moment of truth and a future story to share.

September:

The caterpillars made their cocoons: their spiky hair was used to build a house inside of which the metamorphosis takes place. It is an amazing rebuilding process where everything gets re-arranged and at the end an adult, a creature with totally different shape, needs and purpose comes out. I am imagining it to be a milky white moth but I am not sure at all. Only hoping that one day I will be able to post its image too.

Meanwhile I will keep on scratching my head in wonder; how can so many miraculous events happen in the amazing living world?