[NatureNS] Monarchs Emerge

References: <4C5975C0.6070801@bogan.ca>
From: Steve Shaw <srshaw@dal.ca>
Date: Wed, 4 Aug 2010 15:31:03 -0300
To: naturens@chebucto.ns.ca
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Original-Recipient: rfc822;"| (cd /csuite/info/Environment/FNSN/MList; /csuite/lib/arch2html)"

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Hi Larry,
Related to this, we were out u-picking high bush blueberries in the 
valley (up near you, Cambridge) ~3 days ago, at the end of which I 
checked out the long  'hedge' side of the farmer's field, looking for 
insects.  Along this entire waste stretch there were just two isolated 
smallish milkweed plants growing together (no pods) one of which had 
two Monarch caterpillars on it, each about 3 cm long.  Not sure how big 
they get.   On the way back, about 1 km away on the same side road, was 
an apparently unused grassy field the edge of which was being invaded 
by a large stand (~300) of more mature-looking milkweed plants, many 
with pods, some of which had burst.  We spent about 10 minutes scouting 
this patch but saw no caterpillars or signs of leaf-eating at all.   
Perhaps the Monarch adults only lay eggs on youngish, unpodded milkweed 
plants which perhaps form a better food source?  Or perhaps just pot 
luck in finding any caterpillars at all, from what you say?

The only thing we did see on this patch of milkweed plants quite 
commonly were snails ~1cm long, immobile on the leaves, on either 
surface.   This would have been about 6 PM and it looked as if they 
were living there on the leaves in the daytime and so presumably were 
eating them.   Does anyone know if there is a snail species that is 
able to feed on this plant and whether it uses the alkaloids for 
defence, or can simply withstand them, or metabolize them into 
something harmless?  These were small pale brown snails -- they showed 
no warning colours that might advertize the use of such toxins by the 
snail to potential predators.
Steve
(Halifax)

On 4-Aug-10, at 11:14 AM, Larry Bogan wrote:

> We have two new Monarchs out of their chrysalises this week.
>
> We have an additional five other caterpillars that may become 
> Monarches plus three pupae. Our search of the Common Milkweed in our 
> field revealed very few caterpillars or eggs. This year we have a huge 
> population of spiders, lady-bird beetles, ants, and earwigs in the 
> milkweed that I think had been predating the eggs etc.
>
> Because of this we have been protecting the eggs, and feeding the 
> resultant caterpillars until they pupate.
>
> We have had, at most, three breeding Monarchs at any one time but have 
> seen them mating at least twice. Since the milkweed is a noctious weed 
> we have to control its spread. The milkweed is producing seed pods at 
> the moment and we need to stop seed from spreading so have had to mow 
> the field, keeping only small patches for food.
> Has anyone else seen Monarch emerging?
>
> Larry Bogan
> Cambridge, Kings Co.
>
>

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