Hornworms revisited! Fall 2014
On September 16, 2014 our new student, Christian brought in a rather fat caterpillar his brother found walking on the pavement. It looked very reminiscent of the sphinx moth caterpillars that we hatched last year (see our old webpage).
Observing Big Poplar Sphinx Moth Eggs - fall 2013
On Wednesday, August 28th, students found a moth on the side of the school. Steve brought it to the science room where we kept it in a cage to identify and observe. It looks closest to phots of the Big Poplar Sphinx moth. The next day there were eggs in the cage, so I thought I would have the students observe them under the microscope, not telling them right away what they were.
Several students hypothesized that they were looking at an egg, perhaps a moth or butterfly egg, others thought it could be a small seed. We decided to observe them and see what happened. Also, the "secret" was revealed that a moth had been found and indeed laid the eggs So now we are on a watch to see if they hatch. Another day passed and 2 things happened. 1) The batch of eggs we first observed turned from green to purple, and 2) the sphinx moth laid more eggs! Because we're studying habitats, we'll find out what this moth needs to survive. Here's a good website to explore for more information about raising these moths. If you look at the photos of the eggs on this website, you'll notice that they look very similar to the ones we found. The eggs hatched!!!
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Click on this link to see an informational page about this moth.
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September 6th, 2013: Yesterday late afternoon we began to see the first baby caterpillars. Today we measured them and found them to be 5mm long on average. They were light green, had two lateral (on the side) light green/yellow stripes, and two light green/yellow ridges across the first segment behind their head. They also had an interesting spike or horn on the last segment. They also seemed to rest in a very distinctive "cobra" pose, which we later discovered is characteristic of sphinx moth caterpillars. We spent a fair amount of time describing them in words and labelled drawings.
We researched what they ate (poplar, willow and cottonwood) and made sure they had fresh cottonwood leaves to eat. We learned that the caterpillars also got the water they needed from the leaves they ate, so it was important to have fresh, green leaves. |
September 12th, 2013: We noticed that the caterpillar that was darker green yesterday, now had an interesting and different "thing" at it's tail-end. Also, it's horn was now pointing backward. After a little research, we learned that caterpillars, like many insects, go through stages of growth called "instars". The caterpillar has grown too big for it's exoskeleton, so it has to molt or shed it's exoskeleton. We measure this caterpillar and it was now a full centimeter - twice as large as when it hatched 6 days ago.
The last part of the exoskeleton is pushed back towards the end of the caterpillar and is causing the horn to bend backwards. Once it wriggles out of it's exoskeleton (just like you might wriggle out of a pair of tights), it will be in the 2nd instar stage. |
Observing the development of the sphinx moths
The slides below show the development of our sphinx moth caterpillars (called hornworms). We had a high natality rate (over 50 caterpillars hatched), followed by emigration and mortality. As of this writing (October 21) we have only one caterpillar left and it's a race between the caterpillar and the availability of its food source. With the leaves changing and falling, we hope that our caterpillar will grow large enough to pupate.