Sunday, August 25, 2013
Black Swallowtail Butterflies lay their eggs exclusively on plants in the carrot family. In the wild in this area that means Golden Alexander plants, and, south of Minneapolis, Queen Ann's Lace. In your garden it means dill, parsley, and carrot.
The caterpillars eat the entire dill plant, right down to the ground.
In each instar the larvae usually look a bit different, or maybe a lot different.
This picture is of the 3rd instar for the Black Swallowtail caterpillar. It is preparing to shed its skin here. It quietly sits still on the plant stalk for several hours, not its normal behavior.
Notice all the spines and tubercules on the caterpillar's back. These will get smaller with each instar until they are not present in the 5th or last instar.
Also notice the white 'saddle' in the middle of the back in this picture. This will disappear in the next instar, as can be seen in the picture below.
Notice also the silk threads the caterpillar has woven all around the stem so the old skin will stay attached as it splits and the 'new' caterpillar moves forward.
The caterpillar is about 3 inches long here, 3 times the length it was in the 3rd instar, which is the 2nd picture above.
It is pretty easy to see the difference between the six 'true' legs up by the head and the 10 'pro-legs' or 'false' legs that protrude from the caterpillar's abdoman.
These false legs are like little velcro pads that stick to plant surfaces very well, enabling the caterpillar to use the true legs to help grab and pull food towards its mouth.
I don't think these caterpillars help with fertilization of the flowers since they completely eat every flower, and stem, they can find.
Notice the aphid trying to escape at the bottom of the flower stem. I didn't notice the aphids until after I was looking at the pictures on the computer.
The caterpillars seemed bothered by the aphids when they crawled onto their bodies, especially when the caterpillars were little. But I never saw one get eaten, even if it was on the flower as the caterpillar ate the flower.
At about 2 weeks of age the caterpillars start to wander, and after doing this for 12 hours or so, they settle on a plant stem to their liking, and attach themselves with a silk thread as can be seen below. Now it is ready to transform into a chrysalis, which will appear in an upcoming post.
Tuesday, August 6, 2013
Its colors mimic a paper wasp, but its front legs and head are very mantis like. And any small bug that it catches in its front legs is dinner for sure.
Evolution's adaptive characteristics make for some fascinating creations in nature.
Friday, August 2, 2013
It seems very pastoral in theory, but is the most chaotic and busy place around.
With these aphids the ants don't seem to get the reward directly from the aphids at all.
But look at all the aphids under the 6 feet and legs of the ant. And this is as big as they get, although there are many very little ones.
I measured the biggest aphids here at just under one millimeter.
The whole leaf had over 1,000, and there were 30 leaves on the plant, which means over 30,000 aphids on each plant. I counted 22 plants in this group, so over 660,000 aphids in this colony. Wow!
Their drops of honeydew are tiny, but if they added up to just one water droplet in volumn in a week per aphid, that would be 660,000 drops of honeydew per week. At 27 drops per teaspoon, that is over 7 gallons a week for this colony!
Here you can see one little droplet just released by this litle gal. I have turned the picture upside down so it is easier to see, so this droplet would actually be falling up to the leaf below it, onto the topside of the leaf.
With thousands of droplets falling onto the top surface of the leaf below you can imagine what a sweet, sticky, treasure trove the top of each leaf becomes.
Here you can see each tiny white spot is a droplet. The ants get fat eating these, which they can take back to the nest to feed baby ants with.
The ants also have to spend a great amount of time chasing away other critters who are interested in this enormous food source. They are not very successful.
But other insects come to feast as well. There are at least 8 flies that I can count on each plant at any one time. Lots of them flying all around.
Many are this red eyed species that is house fly size. Its sponge/mop like mouth is picking up the honeydew, but while it eats even more honeydew rains down from the bottom of the leaf above, covering the fly with little specks of sweet dew.
The aphids are growing on the leaf up above and shedding their skins as they grow. The shed skins fall as well. One can be seen under the fly here. It is white.
After a few weeks of this there is mouldy honeydew, fly droppings, shed skins, and anything the wind blows onto the sticky surface. It is a mess!
The entire top of the leaf is covered with this coating of sticky food.
Aphids can be seen on the underside of the leaf to the left. They are dropping more honeydew to the top of the leaf below.
With over half a million aphids and other food animals present, the predators show up. Several Ladybugs were hunting and eating aphids while I was photographing yesterday. The Ladybugs are too big for the ants, but there are so many aphids, they have little impact on their numbers.
This little milkweed patch is an extremely busy ecosystem. Nothing can compare to it nearby for the number of insects constantly entering and leaving, not to mention the over half million that live on it every day.