Prothonotary Warbler

Prothonotary Warbler

Friday, 22 August 2014

Life and death in the back yard



Milkweeds are more plentiful this year, thanks to them being taken off the noxious weed list a few months ago. So Monarchs and other insects have greater nectaring sources than ever.

Common Milkweed
Not long ago, I watched a female Monarch laying eggs on one of several Common Milkweeds in our back yard. Notice the tip of her abdomen curled up against the underside of the leaf.



After she left for other milkweed leaves, I took a close look and this is what I found.....a single tiny egg.


It is a mere millimetre or so in diameter, so clearly another need for macro equipment! I watched this egg, and others, from time to time, expecting it to eventually hatch, and a few days later, this is what I saw.


 A close look reveals an exit hole at the lower left hand side of the egg. At first I thought it meant that the egg had hatched, and the tiny larva would be out feeding. However closer examination, and a bit of reading up on the process, led me to conclude that this egg had been predated. A normally hatched egg is slightly darker at the top. And the larva normally eats the egg casing before chewing a small hole in the milkweed leaf to gain access to the top. If you see a small hole in the leaf like this next photo, it could mean that an egg has hatched and the larva is out feeding.


 While I was photographing the empty egg in the photo above, I watched a small ant come along, and dive into the empty egg, presumably looking for remains of an egg, if not the entire contents.

This ant stuck around for several minutes, breaking into the already empty egg shell, before moving on to other sources of food.

Had the egg successfully hatched, a small caterpillar would have begun the next stage of its life's journey. Unlike some butterfly caterpillars, Monarch caterpillars remain essentially the same colour throughout the several instars (stages of growth) before forming a chrysalis.



This lower photo shows the caterpillar sharing the milkweed plant with quite a few aphids. These brightly coloured aphids are not native, but were introduced. They are very soft bodied and send their long mouth parts deep into the plant to access the sugar rich sap. Often they become so numerous that their sticky droppings give a shiny wet appearance to the leaves below.

If the caterpillar is successful, it will eventually form a chrysalis, or pupa, where it will spend approximately two weeks before emerging as a full adult. I have seen about 20 caterpillars on the milkweeds in our yard, but I have yet to see a chrysalis this year. Unless they are unable to do so, they will typically leave the milkweed plant and form the chrysalis elsewhere.


This is the hoped for end result of all that effort.



But as much as we would like to see a profusion of Monarch butterflies, nature doesn't allow it. Death comes to many of the eggs, as I described above, and larvae.

And death comes to many other small critters using the milkweed plants. The milkweed plants are not carnivorous like some bog dwelling plants are, but they are killers nonetheless. They attract lots of insects, some of them which are critical to successfully pollinate the milkweed flowers. But if you take a close look at the flowers of this plant, you may find something else.....dead insects.

The flower parts of the milkweed are tricky for some insects to manoeuvre on. The parts of the flower separate somewhat. If an insect is very light, they can walk across the flower parts without any trouble. If the insect is heavy, it will be able to pull its leg out from the 'horn' of the flower which may otherwise entrap the insect. If like in the story of Goldilocks and the Three Bears, if the weight of an insect is just right....or just wrong as far as the insect is concerned, then the insect may have one or more of its legs caught in the flower parts and not be able to free itself. This next photo shows a fly, which is dangling down and quite dead.


This next photo shows a slightly larger insect, a type of bee, which I was surprised to find entrapped.

I thought it was a goner as well, but it struggled and a couple of days later, I noticed that it was gone. Some insects may even get to the point of pulling the entrapped leg from its body in its struggles, but when you've got six legs and rely heavily on wings for transportation, I guess surviving with only five legs is a preferable option.

We noticed another deadly event in our back yard recently. With all of the vegetation, it is attractive to Eastern Cottontails. On more than one occasion, they have had nests in our yard, and the adults can be seen all year around somewhere in or near the vicinity of our yard. A couple of little bunnies have been hanging around nibbling away at various types of vegetation.....sometimes the clover in the yard, and sometimes the flowers.


There is no question that little bunnies are cute. But one day not long ago, Marie ventured out into the yard first thing, and saw this sight.


Clearly a bunny had now provided nourishment to a predator of some sort, with only a few clumps of fur and its entrails remaining. We suspect it was a cat, since they are great hunters and more than one happens to roam around the neighbourhood. A bird of prey such as a Great Horned Owl would likely have flown off with it, not wanting to hang around the yard any longer than necessary to capture its prey. Clearly whatever caught this ate it on the spot, and it was not afraid of spending time in a residential area. The gates around the yard were closed, so it wasn't likely a dog, although it is always possible it could have been a fox, which does have the ability to climb. But a cat is my guess.

It is a sad tale concerning the bunny, but nature isn't always pretty.....if it weren't for predators, given the rate that cottontails reproduce, we would be over run with them in very short order!








 

2 comments:

  1. Allen, great posting and great photography. I'm planning on getting some milkweed seeds this fall and planting some in my back yard. Thanks for the informative post!

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  2. You are quite welcome, Dwayne....and I hope your milkweed patch is successful next year!

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