Santa Clarita and Northern Los Angeles County Area
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Western Sheepmoth [Hemileuca eglanterina] Rearing Images

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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. 07, 2005 - Larve molt into 3rd instar. Note the yellow-ish colored spines of a freshly molted larvae at the top of the photo. The yellow disappeared in about 20 minutes leaving a mostly black larvae with gold-tan colored hairs.

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.

3-14-2005 5th instars, some nearly 2 inches long.

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.

The majority of them had pupated by 4-19-2005. These shots show the pupae, the container, and some additional images of the larvae for scale.

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.

The timeline below shows the progress...

Jan.04, 2005 eggs hatch. (about 90) Many losses during first instar.
Jan.23, 2005 larvae molt into 2nd instar (14 remaining)
Jan.28, 2005 2nd instars growing rapidly. No further losses.
Feb.02, 2005 2nd instars getting plump now. Still no losses.
Feb.07, 2005 molt into 3rd instar.
Feb.11, 2005 one looks rather sickly and will probably die.
Feb.13, 2005 sick returned to the group, can't tell it from the others!
Feb.19, 2005 molt into 4th instar.
Mar.14, 2005 molt into 5th instar.
Apr.04, 2005 larvae are wandering a lot and not eating much.
Apr.08, 2005 dirt/plant debris container added.
Apr.11, 2005 some larvae have burrowed into the dirt.
Apr.15, 2005 A few have pupated in the dirt container.
Apr.24, 2005 Only one left to pupate.
May 01, 2005 Pupation complete!
Jun.06, 2005 First adults hatch, and mate! 150+ eggs are laid.

Here is a wild larva photographed on a low-growing Ceanothus bush at the summit of Mt. Frazier on 6-21-2005. There were only two on this one bush, and no others were found anywhere nearby in spite of careful searching.

Here are a few images of the two larvae from Frazier Mt. a few days later. They were switched to Cercocarpus and seemed to do well but eventually the smaller one died. 6-26-2005

These specimens were collected as larvae in northern CA, and are shown here as they were collected from the sleeve on 7-22-2005.

On 8-2-2005, I managed to catch one of these larvae as it was pupating. Note the transparent and very lightly yellow-colored pupae only moments after shedding its final skin. In this state it is extremely soft and fragile. In about 24 hours, the pupa will darken and harden to a more rugged state. Still, it is possible to break and rupture the pupal shell even when hardened, as they are quite brittle and can be damaged by dropping or impact. I learned this the hard way when I dropped a plastic container with several pupae inside. It was not a long fall and the container landed on carpet, but still I lost several when they slammed against the inside of the container. The larva remaining is in its "grub" phase, shrunken and bent as it prepares for pupation.

This batch of eglanterina pupae is from the Mt. Shasta region. Note the yellow colored pupae which molted it's final skin just before this photo was taken (9-1-2005)

At Frazier Mt. summit on 8-25-2005 I baited males with a feshly-emerged female and as I packed-up the car, I allowed one lucky male with particularly dark and interesting markings into the cage with the female, which was still scenting. It took him about 5 minutes to find her and get hoked-up. They stayed together for about 45 minutes on the bumpy ride back down Frazier Mt. then separated at some point on the freeway ride home. I pulled-off and placed them both into envelopes to prevent damage as they both became active again.

Once I returned home, I removed the female from the envelope and placed her on a polished chopstick which was clipped onto a stand at a 45 degree angle. It was about 6pm. The females seem to like this angle for ovipositing. Once she got a grip on the stick she became still and it wasn't long before she started. She laid about 50 eggs in one continuous session of about 90 minutes. She rested for an hour or so then became active again - vibrating her wings for a short time to warm-up. She tried to fly a bit but settled down quickly once I replaced her on the stick. She laid about 27 more ova in the second session and then stopped for the night. I placed her back into the envelope. Mid-morning the next day I took her out of the envelope andplaced her back on the stick. She immediately began ovipositing. After 13 more ova in this thrid session she was done. She tried off and on for several more hours but her ova supply was apparently exhausted. Two days leter she was still alive and attempting to oviposit but there was nothing left.

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