Santa Clarita and Northern Los Angeles County Area
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Burns' Silk Moth [Hemileuca burnsi] Rearing Images

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At the beginning of September, 2005, the pupae from earlier in the year (see below) began to emerge. They eclosed reliably between 8:30am and 11:00am. By 1:00pm most had fully expanded their wings and were allowing them to harden. The females began scenting not long afterwards, sometime around 5 pm. A scenting female is shown below...

As dark approached, the males became excited by the pheromone and started buzzing about the cages. Mating occured within several minutes of placing them together in a small cage. They remained paired for about 90 minutes then seperated.

About 15-20 minutes later the female became active and began fluttering around the cage. This appears to be a "warm-up" time when she would normally be searching for appropriate hosts on which to oviposit. Since she was confined to a small cage, she couldn't go anywhere but still insisted on exersizing for what would have been the 10 flight period. After that she slowed down some and began crawling on the twigs placed in the cage until she located a suitable spot.

In the wild, a twig or stem is preferred, usually at a steep angle to the ground - 90(vertical) down to about 45. This angle allows her to hang comfortably while applying the ova to the twig. Her abdomen is quite flexible, capable of placing the eggs in a mass which wraps around to the opposite side of the twig. 9-13-2005

H. burnsi only creates a semi-ring where other Hemileuca species, such as eglanterina, wrap the eggs completely around forming a complete ring. The burnsi semi-ring mass is shown below. 9-17-2005

The adults shown above were the results of the larvae below... They were found in the hills just north of the Dead Mountains, on Fremont Indigo Bush. The plant was mostly bare and had just begun to produce foliage, so the black clumps of massed larvae were pretty easy to spot. 2-27-2005

By 3-15-2005 they had grown quite a bit. These shots show the larvae in the plastic container they are being raised in. Due to the driving distance to the nearest Fremont Indigo Bush, I brought home a supply and froze it, in hopes it would last several weeks until I made another trip to the Dead Mts. Once removed from the freezer, the foliage is good for about 24 hours before it becomes too dry to eat. I carefully remove and thaw just enough so that it's all consumed before it dries out.

The larvae seem to do well eating from the frozen food section, although the food does need to be changed more often than cuttings in water. Still, it beats the alternative drive to the nearest fresh plant. These pictures were taken 3-21-2005 and show the largest one at about 1" long, a late 3rd instar.

Here are a couple of shots of freshly molted 3rd (left) and 4th (right) instars. 3-27-2005

3-29-2005 burnsi larvae shown in their rearing container (left photo), with the "frozen food section" visible behind it. The tub of frozen Indigo Bush should last the 50 or so 3rd and 4th instar larvae about 1-2 weeks. The other two photos show a 4th instar larvae.

These images photos show a reshly molted 5t instar. Note the bright yellow spines, just like the previous instars. As expected, the bright yellow changes to a burnt- orange color after an hour or so. 4-6-2005

4-3-2005 Some close-up images of 5th instar larvae to show the detailed coloration.

This 5th instar larva is about fully mature and 2" long.

4-20-2005 - A couple more shots of a fully mature 5th instar larva...

On 4-14-2005, these larvae began the process of cocoon building. The larvae shown on in a "grubbed" or "pre-pupal" stage, a sort of nowhere land between functional larva and pupae. The last images show how the larvae dig down to the lowest place in the container and then fashion a chamber out of silk and debris. In the field, this chamber may be at ground level just benieth surface debris, or may be several inches underground.

A close-up image of a burnsi "grub" or "pre-pupa". 4-5-2005 Note that this larva which was about 2" long has now lost a surprising amount of its body mass. Just before burrowing and cocoon building, the larva stopped eating and wandered about for several days. It finally burrowed-in and made its chamber. It took at least 5 days for pupation to occur, once the larva was stabilized in its completed chamber.

Some close-up images of the pupae and cocoons. The 4th image shows several pupae which did not fully complete the process. Since this species does not overwinter in the pupal stage, it's quite possible that these individuals will survive to eclose, but will almost certainly be deformed and not able to function properly as adult moths. 5-23-2005

In early September 2005, the adults began eclosing. A few at first and then in clusters as the middle of the month approached. About half of them had eclosed by September 19th, and sporatic eclosures continued towards the end of the month. The sequence below is of a female which eclosed on 9-19-2005...

The project is now complete. The life cycle continues with the ovipositing female at the top of the page.

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