Larva Lore #5 Sleepy Orange
(Eurema nicippe)
Sicklepod (Senna obtusifolia); formerly Cassia obtusifolia
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The location and survival of butterfly larva depends on the host plant appropriate to the species of butterfly. Since this tale of butterfly larva really involves tales of the host plant, I thought I would start this column with the host plant. Sicklepod is a weed that occurs in disturbed sites. It is commonly found growing in agricultural crops such as soybean, cotton or corn. It has yellow flowers, large compound leaves of 6 oval leaflets and a long thin curved (sickle shaped) seedpods. The plant is often about two feet tall before it is noticed and it is reported to get up to five tall. Senna obtusifolia is recognized as a common host plant for both Sleepy Oranges and Cloudless Sulphurs. While on the Raven Rock Annual Count earlier this year Will Cook and I saw numerous Sleepy Oranges. At some point Will pointed out that the plant in the roadside ditch was Sicklepod, the host for Sleepy Oranges. My thought was "yeah, well OK, nice to know but aren't there some more exciting butterflies and host plants we could find. Maybe even something with a caterpillar or two". On a later butterfly count Jim Nottke noticed an
orange butterfly ovipositing on some Sicklepod in the cut portion of a corn
field. We each collected some leaves with the eggs and then some less-crushed
plant for the anticipated caterpillars. Upon arriving home I discovered that
I had several more eggs than I thought I had. After a couple of days the
original host plant was a little the worse for having been run over by the
harvester and the trip home. Since I hadn't yet located any Sicklepod close
to home and I had to be in Chapel Hill for the day, I contacted Will and he
suggested I check some Soybean fields near Carborro. Yes, there was Sicklepod
and I was able to replenish my supply. When I got home I discovered that I
had even more eggs and some caterpillars LARGER than the ones I was trying to
raise. Two more trips to fields closer to home yielded more Sicklepod
including more eggs and caterpillars! This was getting to be a bit much.
A couple of days later I was biking along the RR tracks near home (in the
city) when I noticed some Sicklepod (only about 18" tall). Plus, along
came a Sleepy Orange to oviposit. I figured I had it made. I didn't have to
drive halfway across the county, I could just ride my bike up to the RR
tracks and get more Sicklepod when I needed it. As I continued on home I
thought about the fact that there certainly were eggs on the plant and did I
really need any more caterpillars to raise. When I got home I found I already
had 15 chrysalises and about 20 caterpillars at various stages. So what did I
do? The next day I took all of the remaining caterpillars up to the RR tracks
and put them on the Sicklepod there. When raising them on cut plants in a container the caterpillars usually sought a fairly horizontal surface on the plant for pupation. However, so far I have not found any chrysalises on the plants where I released the surplus caterpillars. Did they wander off to pupate or were they snatched by a predator? They suspended themselves in a "U" shape with a sling or girdle of silk. The green chrysalis is pointed on both ends with a large hump on the top. See Florida Butterfly Gardening by Marc C. Minno and Maria Minno, page 68 for pictures of caterpillar, chrysalis and Sicklepod. Since I ended up mixing eggs and larva I don't know how long the larva stage was or how long it took for the eggs to hatch. Generally the chrysalis stage was one week. As the butterfly develops in the chrysalis, the center of the hump starts to change to an orange color. Later a black border can be seen around the orange area. This coloring proved to be the upper surface of the forewing. Most butterflies have their wings compressed along the body in essentially the normal position. However, the Sleepy Orange has its wings (and antenna) folded down over its legs, showing the top surface of the wing through the chrysalis. Once it had emerged from the chrysalis and its wings expanded they were quite willing to just hang around for a lot longer than many of the other butterflies I have raised. They do keep their wings closed when perching which makes it hard to study the upper wing patterns. Since I ended up mixing eggs and larva I don't know how long the larva stage was or how long it took for the eggs to hatch. Generally the chrysalis stage was one week. As the butterfly develops in the chrysalis, the center of the hump starts to change to an orange color. Later a black border can be seen around the orange area. This coloring proved to be the upper surface of the forewing. Most butterflies have their wings compressed along the body in essentially the normal position. However, the Sleepy Orange has its wings (and antenna) folded down over its legs, showing the top surface of the wing through the chrysalis. Once it had emerged from the chrysalis and its wings expanded they were quite willing to just hang around for a lot longer than many of the other butterflies I have raised. They do keep their wings closed when perching which makes it hard to study the upper wing patterns. The butterfly probably overwinters as an adult in this area. Some people have seen them around on mild days in January. This Fall/Winter form has darker coloring on the underside of the wings (from tan to light brown rather than pale yellow). I await your contributions or suggestions for the next Larva Lore column. Charles Cameron, 336-852-9211, ccamer@triad.rr.com |
"fall form" of the Sleepy Orange, Eurema nicippe Larva Lore
#3
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