Late Summer Cactus Fun!

Since some of our regular readers are NOT from Arizona, I thought a post about some of our native plants is about due. While our "rainy" season is just about over, most cacti do not show many external signs of the extra moisture. Most bloom in the spring, and those blooms have long since gone to fruit and long since eaten by birds and bugs.

One exception to the above are some varieties of barrel cactus. We've got a large one in our yard that is still blooming and are some months yet from ripening to fruit and seeds. The flowers are large and striated, and attract a lot of insects. The shots here show both flower buds that have opened days previously and if pollinated, will develop into fruit, as well as some buds that have yet to flower. Interestingly, we've a second fishhook (so named because of the bend in the needles) barrel cactus that, except for size (smaller), looks identical to this one. The smaller one however, which is from Mexico, blooms early in the Spring, a good 5 months ago!

While shooting the blossoms here, a bee loaded down with pollen, was having fun swimming through the sea of stamens - only his pollen laden rear legs and striped abdomen are visible (right photo). I wanted a firm identity of the bee because the high contrast stripes didn't look like a honey bee, and sure enough, Carl Olson, an entomologist at the University of Arizona identified it as Diadasia rinconis, also known as the Cactus Bee, a solitary bee (doesn't live in a hive) that builds a nest in the ground.

Though I don't have any before pictures, there was a 7' (2 meter) tall prickly pear that was encroaching on our secondary parking spot in front of the house - not something you want to walk into at night! The end of July, I hacked off it's upper half and severely trimmed it, knowing it would sprout new pads. Sure enough, here we are 5 weeks later, and tiny little growths are dotting the edge of the pads I trimmed.


And like many cacti, I swore I didn't come close to it, but I must have, as evidenced by the tiny glochids stuck in my finger after taking the above pictures. They are so small that you generally don't feel them initially, but they work their way in with time and are irritating, if not painful. Painful is when you get an armful of hundreds of them, not just a couple as shown here. That is why standard equipment when out walking or hiking in the desert should include a good set of tweezers for pulling out the tiny barbs.




The last pair of pictures is of a beetle that spends a lot of time on a prickly pear over in our neighbor's yard. Most every night when I go out on my walk I see a few of them out on the cactus, but never during the day. One clue to that behavior is that late one afternoon I saw a 10" (25cm) lizard searching through the branches of this particular cactus - looking to make a meal of these guys! I never paid much attention to what the beetles were doing, but they didn't move much, staying in the same approximate place during my nearly hour walk.

In taking their picture the other night, their mission became more obvious - the photos are of the same beetle, with slightly different perspectives. The one on the right shows he has eaten off a bit of skin off a pad, and apparently spends time there lapping up the ooze the plant exudes!

These guys are a pretty good size, 5 or 6 cm (2" to 2.5") long. Note the ant for scale on the left image. They look formidable too - check out the grappling hooks at the end of it's legs - perfect for hanging on to cactus spines... Melinda claimed she got the willies and would get nightmares after seeing the shots, so she will likely not read these last paragraphs!

Again, I bow to Carl Olson at the U of A for identification and he notes that it is a Moneilema gigas, identified by the horns at the side of the thorax and the white antenna segment. The common name, as could be expected, is the Cactus Longhorn Beetle. Evidently, besides the adults damaging the cactus skin, the larvae work on the roots of the plant as well, placing it in some danger with long term infestation. Fun stuff!