I've been back at "Ketelsen West" for nearly a couple weeks. When I make plans to be out of Tucson in July, everyone always asks how I can miss the monsoon rains - so welcome to the desert dwellers. Well, I miss the start of the 2+ month rainy season here, but also a lot of the hottest weather and the wondering when the first storms will arrive... The one thing that I do hope I don't miss is the flowering of my cereus repandus - night-blooming cereus cacti! They typically start their spectacular blooming shortly after the monsoons start and last through most of the rains till it cools off the end of September. And while the flowers are indeed impressive, what is fun and "sporting" is capturing the pollinators that inevitably come by to feed on the flower's nectar and in that process, distribute pollen among other plants and blooms. I was in luck - shortly after my return, a quartet of flowers bloomed the same night - on the same arm of the cactus! At left is how it appeared right about sunset - the 4 telltale buds were swollen and about to bloom the next few hours. At right, by 10pm, they were open and awaiting action!
But in recent years, I've enjoyed capturing the rustic sphinx moth pollinators. They appear randomly during the night, perhaps drawn by the very subtle (to me anyway) odor of the flowers, or something else that tells them there is food here... The challenge is always to capture as many as their flighty visits, without taking a million photos! Of course, I could sit there and man the camera myself, pushing the button as they visit to feed. Likely also it would be straightforward to rig up something to do it automatically as they come by. I was able to capture a few of the earliest visitors manually, as they started visiting shortly after the flowers opened. With my head-mounted red light, they buzzed my head as they approached, seemingly as large as a bat as it came past me to feed. There was no missing their approach, and even during their stay, I could see the cat's-eye reflection of my red lamp from their eyes! The most fascinating thing to me is there nearly 15cm (6") long proboscis, so tried to take their photo before they landed on the flower. The results here demonstrate that successful plan.
But I was not prepared to stay flower-side all night. I increased my chances by setting up the camera so all 4 flowers were in the image. That way, if any moths came to any flower, I'd document its visit. Also, I used the on-camera flash (on my 10-year old Canon XSi) to illuminate the scene. Taking a photo every 20 seconds (3 per minute, 180 per hour!) I was hoping to catch a few moth visits! 5.5 hours later, the camera and flash were still going after nearly 1,000 photos! The next day I downloaded the all and went thru it frame-by-frame - I had caught over 80 images of moths! That included 4 frames where there were 2 moths in the frame - an absolute first for me! They weren't consecutive frames either, so weren't the same 2 moths hanging out together! These two frame sets show the 4 images with moth pairs in them...
What is most amazing about these moth images is the length of their probiscii! At least when they are flying around the cereus repandus flowers they appear to be fully extended. I believe I've seen images showing them coiled up when not in use, but flying around with something extended that is larger than your wingspan must be dangerous, if not at least a little risky! The image at left is quite incredible! Be sure to click on it to load the full resolution image...And some of the moths dig so deeply into the flowers. Either they are a little smaller, or perhaps they've got a shorter or broken proboscis, and need to go deeper to feed. Check out the image at right - can barely see the moth body...
So this particular night (19 August) was a particularly busy one! I had stopped the camera at 4:30am, but stopped by a couple hours later to do some close-ups to compare to some I had taken earlier in the evening. At left is a "before" photo showing the abundance of pollen and the still-green stigma and pollen-covered anthers... At right is a close-up of the stigma after a busy night of pollination. You can see the moths have transferred a lot of the little round pollen grains, and it appears that the moths have also left behind an abundance of their scales - the feather-looking filaments that appear to be stuck to the stigma. Note how bare and naked the anthers are, now devoid of pollen...
At 6:00 the sun was just coming up and the flowers were about to close. I set up the camera once more with the timer to take a photo every 8 minutes for 3 hours. Rather than make a time-lapse, I made a GIF, shown here demonstrating the rapid closing of the flowers once the sunlight hits them. It looks like the bud/bloom cycle continues, as does the monsoon rains. Will keep my eyes open for more photo opportunities!
