Showing posts with label Dogday Harvestfly. Show all posts
Showing posts with label Dogday Harvestfly. Show all posts

Saturday, August 18, 2012

Black and Yellow Argiope (Argiope aurantia)

A large, robust spider, the female Black and Yellow Argiope can attain a length of about 25 mm, the considerably smaller males, as is often typical among spiders, are only about 5 mm long. To date, a Cicada or Dogday Harvestfly is the largest prey I have ever seen one of these spiders take down.


The white zigzag pattern in many orb weaver's webs is called a stabilimentum, so called because at one time it was thought to stabilize the web. But experiments have shown that the stabilimentum – and the spider itself – reflect ultraviolet light. Since many insect's eyes are sensitive to the UV spectrum and flowers often reflect patterns visible in UV to attract insect pollinators, the current theory in vogue is that the stabilimentum and spider may act as lures to entice insects into the web. However, as adult Cicadas don't eat it's not likely this one was tricked into flying in the web – it was unlucky and simply blundered in.


A couple more views of this harmless, attractive arachnid.

Friday, August 13, 2010

Dogday Harvestfly or Annual Cicada (Tibicen sp.)

One seldom encounters these large, fearsome looking but completely harmless insects at close range as they generally stay high up in the trees. The singing of the Dogday Harvestfly signals the onset of late summer. According to some sources the saw-like buzzing of the males measures 100 decibels at twenty yards and up to 120 decibels at close range.

Cicadas belong to the order Hemiptera, which includes insects such as aphids and true bugs. The nymphs live underground for three years feeding on the roots of oak and pine, and their exuviae can often be found on the trunks of these trees near the bases. The adults do not eat.

Tuesday, August 26, 2008

Metamorphosis

The Dogday Harvestfly (Tibicen canicularis) goes through incomplete metamorphosis, having only three stages in its life cycle: egg, nymph and adult. The nymphs live underground sucking juices from tree roots, preferably pine trees.

After three years the nymphs emerge and go through their final molt, changing into winged adults. The cast off exoskeleton may be seen in the picture below. As is the case with many insects the adult cicada does not eat; it lives long enough to reproduce and then dies.

It's going to take a bit of luck to get a shot of an adult cicada as they tend to spend their time high up in the trees.


Dragonflies also go through incomplete metamorphosis, spending the second stage of their life living a predatory aquatic existence. This discarded nymphal exoskeleton (exuviae) is about 2½ inches long and likely belonged to a skimmer or a darner.


The Monarch Butterfly (Danaus plexippus) goes through complete metamorphosis ... egg, larva, pupa and adult. The larva in following image is feeding on Swamp Milkweed and this one seemed to have a marked preference for the seed pods. The caterpillar ingests toxins present in the sap of the milkweed plant and the bold colors advertise its poisonous nature.

I'm going to be keeping an eye out because this caterpillar looks like it will be ready to pupate any day and this looks like a good opportunity to make a photo essay of the change from larva to adult.

These are the seed pods the caterpillar ate in only two days ...

... and it's moved on to the leaves and still going strong!


Unless I find another caterpillar it looks this photo study of a larva metamorphosing into an adult Monarch won't be finished.

I checked out the caterpillar the following morning; it was torpid and looked like it was ready to pupate. Two hours later ... it was gone. Maybe a bird got it. Birds have to learn to avoid the warning colors and it seems like one might have tested its luck.