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On 4-6-2005 I visited the Granite Mountains looking for fordi host plant (Cymenopterus panamintensis) and larvae. It was still pretty early in the season and after hours of searching I had found only about a dozen plants, most of which were void of eggs and larvae. The host plant is quite scarce, but near the end of the day, I finally found a few plants with eggs and larvae. The eggs varied from yellow and freshly laid, to dark brown and about 2 days from hatching. The larvae ranged from freshly hatched to late 2nd instar. All of these stages were to be found on the same plant.
The first two shots show the largest of the larvae on the native host plant. The remaining 4 show examples of the host plant and the rocky environment in which is grows.
Back in the lab on 4-7-2005, the eggs were still hatching and I managed to get a couple of interesting images of the larvae as it chewed its way out of the shell, and another of the fresh and wet-looking larvae just after it left the shell (left two images). The next two shots are of a 2nd instar larva, now eating arguta host. The right two are 2nd and 3rd instars on 4-11-2005. The larval coloration from 1st to 3rd instar is fairly consistant until the 4th instar.
On 4-12-2005, the first of the group molts into its 4th instar bands (affectionately called "stripers"). The first 4 shots show the 3rd instar larva with its skin stretched tight as it prepares to molt. The next two images show the molting process, and the remaining images are of the freshly molted 4th instar. Note that the head capsule and forelegs are a creamy white color and probably still somewhat soft. After about 30 minutes or so, these areas turn black as the exo-skelital shell hardens.
As mentioned above, the larvae are being raised on T. arguta in the lab, as C. panamintensis is much more scarce and difficult to obtain. A small container is used for the smaller larvae, up until they get their stripes. Interestingly, many of the larvae seemed to prefer resting and molting off of the host plant. I've noticed this behavior with other swallowtail larvae as well.
Its been suggested that the larvae find their way back to the host plant by using smell or sight. However, it appears that at least part of their method involves the use of their own silk. The larvae appear to create a silken highway from the host plant to their resting spot. The same spot is frequently reused. As the larva moves forward, a silken path is laid-down using a side-to-side motion of its head, where the silk gland is located. Repeated trips to and from the resting spot results in a "snail-trail" which is easily visible under the right light angle.
The images below were taken on 4-14-2005 and show the plastic container, silken paths, and 4th instar larvae.
Some additional images of 4th and 5th instar larvae, molting, and a rearing container. Note that the container shown is suitable for smaller larvae, however, larger ones (small 4th instars and up) require an open-air container. Several larvae died in this container, probably due to excessive humidity and close confinement. As they grow, the large larvae should be allowed more space and the best possible ventilation to prevent losses. 4-17-2005
Here a 4th instar molts into 5th... 4-27-2005
The larger larvae were moved to a hamper to provide more space and better ventilation. Host plant cuttings in several containers of water with small holes in the top are provided for food. CDs (yes, they are AOL CDs - there really IS a use for them!) are taped to the bottom of the bottle to help provide stability. 4-24-2005
It has long been said that fordi might be raised on Fennel, but there are many reports of failure. Some have suggested that if larvae are started on Fennel host from moment they hatch, that they can complete their life cycle successfully. Others have suggested using a live Fennel plant, still growing in the ground. I selected a small group of 5 eggs and started them using Fennel cuttings. I accidentally squished one 2nd instar, and another 3rd instar died in the process of molting. This shot shows 3 remaining 4th instar larvae. 4-24-2005
Note: As of 5-29-2005, one larva on Fennel survived to pupation. It looks healthy and will hopefully survive to emerge next spring or the following year.
As the larvae approach maturity they purge their gut in one messy stool, and begin to wander in search of a suitable place to pupate. Wandering larvae are placed in a paper bag which provides a dark and secluded location where they feel safe to spend the next year or more before they emerge. 4-24-2005
Once a suitable location is found, the larva spins a silken pad and secures its rear feet to it. It then spins a silken strap around its upper body to help suspend itself. Unlike many butterfly species which need to suspend themselves vertically from the tail, many swallowtail species can attach themselves to any flat surface, horizontal or vertical.
Finally, the suspended larva sheds its final skin as it pupates. The left image below shows an individual which failed to suspend itself but managed to pupate anyway on 4-24-2005. The right image shows a properly suspended pupa. 4-25-2005
On 5-3-2005, I was fortunate enough to have the camera ready when this larvae shed his final skin. The sequence is pictured below...
These mid-4th instar larvae (there are 2 of them like this) seem to be missing their white/cream bands. At first I thought they might be ready to molt, but they are not quite large enough, and are still eating with the rest. Normally, a ready-to-molt larvae will select a resting place somewhere secluded, and remain motionless for 1-2 days before molting. These two will be monitored to see if there is anything else unusual about them.
This larva escaped during a cage cleaning. After searching the room for 2+ hours, I finally discovered it in the closet, cleverly disguised as a fordi lapel pin. Nice try, but in the end it went back into a paper bag to finish pupation. 05-09-2005