Tuesday, June 24, 2014

Yucca Bugs

Leaf footed bug - REK
June is the time that the yucca stalks are filled with beautiful white blossoms.  With them comes a special set of insects which make their living on them.  We previously discussed the tight relationship between yucca and the yucca moth, its prime pollinator.

REK
Another common insect found on the yucca blossoms is a leaf footed bug.  These were clinging to the petals and nearby stems, frequently found as mating pairs.  These bugs have widened leaf-like tibia on their hind legs, easily distinguishing them from other bugs.  When approached close up with a camera they frequently crawl around to the back side of their perch rather than flying away.

The leaf footed bugs are in the the family Coreidae which feed on plants.  They have a drill like mouth that is used to inject digestive enzymes into the plant before they suck out the externally digested meal. The enzymes digest cell walls, liquifying its content and can break down some plant toxins.  This allows the bug to feed on plants which other species cannot use.  Leaf footed bugs can give off a bad odor if disturbed.

The leaf shaped hind leg is especially prominent on the species I found.  Its distinctive color pattern led to an identification as a Leptoglossus species.  When they fly they make a faint buzzing sound and their legs hang down like a wasp, a fake warning to man and beast.  They are harmless to humans, commonly found feeding on yucca and other related plants.

L. clypealis mating - REK
There are four species of Leptoglossus, all seen together on this web page.  The western leaf footed bug - Leptoglossus clypealis was the best fit with its prominent zigzag band across the back.  Leptoglossus zonatus was a close second, with its jagged line but it has two light colored spots on the forward part of the pronotum that mine lacked.

Pointed clypeus extending forward like a unicorn - REK
Spiny clypeus - Joyce Gross
The key feature of Leptoglossus clypealis is a thorn-like clypeus extending from the front of its head like a six-legged unicorn.  My initial photographs didn't show this as I use only a pocket camera (Panasonic Lumix DMZ-ZS5), so I went back to the yucca and bagged a Leptoglossus for a trip to the freezer.   Sure enough, there was a sharp clypeus seen above in all its glory.

I have been following these L. clypealis on our yucca for a number of years and they never seem to do any significant harm.  On the other hand there are a lot of them around so freezing one probably hasn't upset the balance of nature.

Detailed photographs at this site.
Lots of detailed information is at this University of Florida link.

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