Trinity River Audubon Center - June 21, 2013

I am out at the Trinity River Audubon Center on the first day of summer 2013 and it is a beautiful day.  Mid to upper 80's and sunny.  The only bad thing is that I forgot all of my insect collecting jars.  Thanks goodness I had my camera.

 

I went out to specifically find more snout beetles to see if they also have the "bacteria" I found on the 14th.  I can see the damage they have done to the plants, but can't find a single one. 

 

Found many Argiope - usually clustered close together - within 1 to 1.5 meters.  Female body size is about 2-3 cm.  They have lots of growing to do before mating.

 

Found one Argiope web with a hole in it and no spider.  Probably snatched up by a bird.

 

This is the back of the web.  Notice how the stablimenta hide the spider.

 

 

 It is early in the day and I came across this dragonfly sunning in a small clearing.  Body and wings oriented directly at the sun.  He let me get very close.  They are such good fliers that it must have known I was no treat to him.



I found one of my favorite spiders - a jumping spider.  She had just captured a homopteran that was as big as she was.  These spiders have excellent vision and, as I moved around the plant, the spider kept moving to keep facing me.

Notice that you can see the retreat this Salticid has built.

 

Of course, I just had to get as close as possible.  The poor little spider became so alarmed that it dropped its prey and hid.  I found it again and it faced and threatened me by shaking its fuzzy pedipalps - the two shortest "arms" near the face.

Here is the sad part.  Fire ants are constantly scouting everywhere for prey.  While the spider was hiding and then trying to scare me off, an ant found the dead hopper.  Soon it had recruited several of its sisters to help begin dragging the hopper off. 

 

I backed off to watch and see what would happen.  The spider watched the lost prey from a distance, but wouldn't approach it because of the ants.  Sorry about that.  Last time I checked the ants had the hopper about half way down the plant. 

 

The spider, threatened by me and having lost its prey to fire ants decided to hide out in its retreat. 

 

While I am sorry I caused the spider to lose its prey, it should have no trouble making it up.  The homopterans, or hoppers, are everywhere.

 

 

 

 These are beautiful animals.  Notice the stripe on the top insect continues through the eye.

 

One more very interesting, and rather large insect I found is this wheel insect.  About 3.5 cm (1.4 inches) from head to tail. 

Now for some of the plants at TRAC today.

 

The Texas Skeleton Plant (Lygodesmia texana)  Note that it has not disk flowers, only ray flowers.

 

 

Black-eyed Susan (Rudebeckia hirta)

 

 



 

 

Firewheel (Gaillardia pulchella)

Wright's Vervain (Verbena wrightii)

 On the back of a leaf I found a cluster of insect eggs.

 

 

 I took them back to the lab to see what I could find with the scanning electron microscope.

 

[100x]

 

 [350x]

The top of the egg has a definite pattern to it.

 

 [1,000 x]

 

 [1,200x]

There are tiny air holes in the top of the egg. The distance between marks on the scale is 4.0 microns making the holes about 1 micro in size.

 

 

It was a pretty good first day of summer at the Trinity River Audubon Center.  Even though my current focus is on spiders and insects, it is impossible to pass up the flowers. 

 

M. Gans

 

All images are under the Creative Commons Attribution-Non-Commercial license.  As long as you give credit to Eastfield College, Mesquite, TX, you may use, alter, transmit, or copy any of these images.  They may not be sold.

 



 



 



Trinity River Audubon Center - June 14, 2013

June 14, 2013

Back at the Trinity River Audubon Center off of I-45 and Loop 12 just a few minutes south of downtown Dallas.

Trinity River Audubon Center

6500 Great Trinity Forest Way (formerly 6500 S. Loop 12)

Dallas, TX 75217

Phone: 214-398-TRAC (8722)

 

The location I found today is not actually on the trail map.  It is on a mowed trail that begins at the parking lot.

 

 

 

This is an excellent location with many tall plants (still green because of the rain we are having this month).  the trail runs approximately north and south which puts one side of the trail in sun and the other in shade.

 

I found many young Argiope spiders on webs with stabilimenta.  These are all female, about 6, and I hope to watch them through out the summer to see when they make egg sacs.  Because they are located so closely together it seems reasonable that they are probably sisters from the same egg sac.

 

Eastfield College has a gene sequencer and it would be an excellent project to sequence some genes  and see if this is true.

 



Argiope positioned on her stabilimenta.

A closer view of the spider.

 

Another Argiope female, but with a different stabilimenta pattern.  One theory is that by positioning herself on the stabilimenta, the spider becomes less visible to predators such as birds. 



I know that the male Argiope are much smaller than the females.  I found several of these smaller webs with stabilimenta that I thought might belong to males, but have yet to find one.

 

At one point I saw a very small spider moving quickly across this web - very quickly.  As I watched the spider moved to the top of the web and then ballooned away. 

 

Ballooning is a process that spiderlings use to disperse.  They climb to a high branch or spot and begin to release a silk thread which is picked up by the wind.  When they get enough silk out it lifts them into the air where they will float to a new location.

 

I hadn't noticed the ballooning silk so I suspect the little spider was being pulled across the web as much as crawling. 

 

 

 I found several of these crab spiders on vegetation.  The sit with their two front legs extended waiting to grab what every comes by.

 Here is another cobweb spider which has formed a web between two leaves. 

I found lots of snout beetles on many of the taller plants.  These guys were ridiculously easy to capture because of a defensive behavior.  When disturbed they simply let go of the leaf and fall.  All I had to do was open the collecting jar, put it under the leaf, and poke the beetle causing it to fall into the jar.

 These little guys are amazingly tough as I found out when I tried to pin them.  I couldn't even get their legs to move laterally. 

 

Leica S8AP0 Dissecting Scope

 

 Image of collected beetle.  . Notice the backward facing antennae.

 Close up of eye.  There are slits in the proboscis for the antennae to fold into.

Some heavy duty tarsal claws.

 

Hatachi S-3400N Scanning Electron Microscope

 

 Hello there.  Front-on view of eyes.  [93x]



Head and thorax.  You can clearly see the slit for the antenna and the large tarsal claws.  [20x]

The eyes have what appears to be eyelashes even though this animal does not blink its eyes.  Notice the Y-shaped hairs to the right.  [110x]

 

 

 I will admit that I am pretty excited about this.  It appears that the ommatidia are surrounded by what looks like bacteria.  Definitely needs further investigation.  If I can collect more of these snout weevils and confirm many or all of them have the "bacteria" around their ommatidia, I will attempt to culture them.  (Sadly, when I went out on the next week I couldn't find any snout weevils in the same location though the damage to the leaves in the area showed they had been there.)   [800x]

 Ommatidia with surrounding rod shaped structures.  [1,900x]

More of the bacteria-like structures in the hairs above the eye.  Could be some plant material or residue.  [400x]

 

Homopterans, or hoppers, are true bugs - actually the only insect that can be called a bug. On most stems there are hoppers who also have a pretty interesting behavior.  They hide behind the stem of the plants to avoid predators.  If you reach out for one of these bugs they will quickly scoot sideways behind the stem.  Reach behind the stem and the scoot back into view.  You can chase them around for a while until they finally fly away.


Note:  David H. Kattes in  his book Insects of Texas states that order Homoptera has been absorbed into order Hymenoptera.

Kattes, David H. Insects of Texas. College Station: Texas A&M UP, 2009. Print.

 Close up of the bottom hopper from the image above.

 Close up of the top hopper in the previous image.

Leica S8AP0 Dissecting Scope

 Back in the lab.

 Collected insect in the lab.

 

 

 

This is the flower of the Illinois Bundle Flower - Desmanthus illinoesis.  The fruit of this wildflower can be seen in the June 4 blog.

 

From Wildflowers of Texas - "These clusters are much sought for use in dried arrangements.  High in protein, this plant is considered one of our most important native legumes, for livestock and wildlife.  Readily eaten by them, it is an excellent range-condition indicator."

 

Ajilvsgi, Geyata. Wildflowers of Texas. Fredericksburg: Shearer Publishing, 1984. Print. Illinois Bundleflower - Desmanthus illinoensis P. 57 

 

I welcome your comments on this blog - really - I mean it.

 

 

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Feel free to use, copy, or edit as you see fit, but be sure to give attribution to Eastfield College, Mesquite, TX.  Images may not be sold.