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Below are shown larvae hatching from an egg mass in the lab. Around 90% of this mass of about 100 eggs hatched successfully. They stayed with the egg mass for a day or so, and then began to "herd" [time lapse video] to other areas of the provided host plant cuttings. Somehow, a "leader" starts the procession, and the rest follow immediately behind. At some point a feeding location is chosen, and they begin to feed collectively.
Fresh 1st instar larvae are shown below on Cercocarpus the (Mountain Mahogany) host. There are about 80-90 of them at this point. Many died-off during the 1st instar, a few at a time, up until the second instar molt. I could not find a reason for it. They would simply get weak and fall off the plant, then slowly crawl around until they died. Replacing them on the host didn't seem to help, as they would just continue to fall off.
Perhaps 80-90 larvae are too many to keep together. The conditions were around 65F, with good circulation, and relatively dry with no condensation. Even though there was plenty of space and host plant, it's possible that their natural tendancy to pack tightly together prevented proper feeding or maybe allowed disease to propagate. It would be interesting to compare the losses using identical conditions, but limiting the number of larvae to about 10-15 per group.
Just prior to molting they became inactive and didn't move for about 2 days. After the third day of inactivity, they molted into 2nd instar. The freshly molted 2nd instar larvae are shown below. Their shed skins can be seen at left. After molting they became active again, and also appeared to grow more rapidly than the 1st instar. There are 14 remaining larvae shown here. No further losses have occurred.
Below are shown the 2nd instar larvae, now a few days older and growing rapidly. The third picture shows a procession of larvae, feeding along the way as they travel. The larvae have never attempted to leave the host plant cuttings at any time. Even so, a ventilated but closed container was used to house them.
A couple of shots of that container and host plant water jar are included. The outer container is made from a clear plastic dog treat container from Costco. The lid is partially cut out and a circle of nylon stocking is stretched and taped in place to provide ventilation.
The water jar is a plastic prescription bottle. The lid is a child-proof type, and is actually two parts; an outer white threaded cap, and a softer plastic inner liner. The inner liner can be removed, and seals very nicely onto the top of the bottle. Small star-shaped slits can be cut into the liner so that host cuttings can be poked-through it into the water below, while fitting tightly around the twig-stalks, preventing the larvae from crawling into the water.
Feb. 02, 2005 - 2nd instars getting nice and plump. I expect another molt soon.
Feb. 11, 2005 - 3rd instars, a few days after molting. Growing rapidly. One looks sickly and will probably die.
Feb. 19, 2005 - molting into 4th instar. Fresh larvae are very light, and the spines are yellow and compressed. After about 30 minutes, the spines are completely expanded and very bushy. See molting video on the eglanterina video page.
During the process of expanding the new spines, the larvae performs a "backrolling" activity (watch the video), presumably to aid in filling-out the spines.
After several hours the coloration fades dramatically, the larval skin returns to a shiny black, and the bright yellow dulls to a burnt orange. Below are various images of the event.
The still images below from the video, show the 3rd-to-4th larval instar molt. The image progression shows the 3rd instar larval skin break just behind the head, and the larva work its way out of the old skin. Note the wet-looking, compressed spines of the freshly-molted 4th instar larva. After crawling clear, it expands its spines over about a 30 minute timeframe.
3-16-2005 5th instars again, some of which are freshly molted (golden-yellow spines). The open-air rearing cage is shown in one photo, and some close-ups of all 14 larvae in a temporary holding cup while the foodplant is being changed.
4-11-2005 The larvae have been wandering around the cage almost continuously for nearly 10 days now, and eating very little if anything. It appears that only the smallest of the larvae are still eating. I prepared and placed a small container of potting soil covered with some plant debris into the enclosure. After a few days, several of them burrowed into the dirt and formed a crude chamber, apparently for pupation.
By 4-17-2005, some of the larvae had pupated. The images below show the typical size of the pupae, a few partially exposed pupal chambers in the dirt container, and one larva still on the hunt for a place to dig in.
On 6-6-2005, a pair of adults emerged. Unfortunately, they emerged in a small contianer with slippery plastic sides and were unable to hang upside down to inflate and dry their wings. The adults were left alone in a small screen mating cage but were unable to mate due the lack of mobility caused by their malformed wings. After a couple of tries, I was able to hand-pair them at about 11am. They stayed together for about 2 hours, then seperated on their own. An hour later the female began laying eggs on a stem of Cercocarpus.
The following day, two more males emerged, but this time they were in a screened enclosure so that they could climb to the top and expand their wings properly. I discovered one of them just as he had emerged and was able to relocate him to a hanging stand in the lab for some pictures. These first 4 images show the freshly emerged adult in the process of inflating his wings. The last two images were taken when the process was complete. 6-7-2005
At this point the project has come full circle - back to the egg stage. Some of the eggs will be placed into a small closed container, and then into the refridgerator where it will remain until next spring when it will be removed to warm up. This breaks the eggs' diapause and allows them to continue to develope and hatch just in time to take avantage of the new spring growth.
The rest of the eggs will not be refridgerated, to observe the time needed until hatching occurs without a simiulated winter diapuase. Fortunately, host plant is available all year around so no matter when they hatch, there will be something for them to eat.
