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Index of Subjects Steve, I agree with your observations on ages of plants to look for caterpillars and eggs. We have a wide age-range of milkweed in our field - We usually find the eggs on very young plants ( ~10 cm tall) and caterpillars on modest sized plants. My theory is that the Monarchs have learned that the caterpillars are best growing up with the plant. If you have ever seen the size of the caterpillar that emerges from that small egg, it is miniscule and would have a tough time eating those larger leaves of the mature milkweed. The milkweed patch that I did not cut is made of mature plants and were probably too big at the time the butterflies were laying. Larry Steve Shaw wrote: > 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) >
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