Monday, August 25, 2014

Argiope trifasciata hatchlings

These are hatchlings of an Argiope trifasciata. Each has a body length of 1 mm. Body length includes the head and abdomen but not the legs. The females will grow to be up to 26 mm long.



The first photo is from her first egg sac, which numbered at least 500 spiderlings. According to the literature on this spider, up to 1000 spiderlings can emerge from a single egg sac. The second photo is from her second egg sac, which numbered only a few hundred individuals. In trying to figure out why the spiders are sometimes orange, sometimes yellow, it appears to me that they are yellow in bright light, such as direct sun or a close flash, and orange in the shade or dim light.

Argiope trifasciata is reported to overwinter in the egg sac, so these hatchlings must attempt to make it to adulthood and make egg sacs by Winter. Adult females can be found as late as December. This is the second brood of this spider, as each egg sac hatched after only a month.

Sunday, August 24, 2014

Egg sac of an Argiope aurantia

This is an egg sac of an Argiope aurantia orbweaver. It's about 2 cm (3/4") in diameter. The array of threads surrounding the egg sac help to protect it from predators and parasites.


Saturday, August 23, 2014

Theridion llano, a Texas Native

These appear to be the first photos of the tiny cobweb weaver Theridion llano, a Texas native. The spider has a body length of 1.5mm. It crawled out of a dried monarda seed head.




I owe thanks to Laura P. and Chad Heins on BugGuide for helping me to identify this, as well as to Allen Dean for confirming the identification. Here is the BugGuide entry for this spider.