Orchid Foes--and Friends (a follow-up)

A daily survey of the orchid collection provided this little vignette.

The Orchid Weevil, Orchidophilus aterrimus (Waterhouse) was about to be attacked by a Jumping Spider.

Ah, I thought what a great thing. Biological control in action. But alas, it was not to be.

But after a fraction of a second, the spider released the prey and moved away. Several bouts were observed in just a few minutes time and then the spider hopped away. Note the weevil is firmly attached to the substrate. So that got me to thinking what makes a "successful" pest.

In this instance, perhaps, the spider could not penetrate the tough exoskeleton of the weevil. Entomologists will tell you difficult it is to pin a large weevil. A #5 stainless steel pin often will not penetrate the exoskeleton of the specimen. If this is working in this example, it is surprising the spider's chelicerae could not find a membrane or other soft point to penetrate. But after several attempts it could not.

And, perhaps, the weevil excreted a chemical of some sort that discouraged the spider. But if this were the case, the spider would not have made repeated attempts at capture.

The weevil stayed "glued" in the same position for 15 minutes until I decided it was time for the alcohol treatment. The spider wandered off. There are not many food sources in the shadehouse so I hope the spider will sharpen its chelicerae for the next encounter.

The spider. It is a Jumping Spider, family Salticidae. There is a great spider site on the web dealing with Aussie spiders. But I cannot reliably identify the genus of this little spider so will not guess. Perhaps, a reader will be able to put a name on it.