Thursday, March 3, 2016

See Orange Sulphur Laying Egg

Text and photos by Laurie Sheppard

Spring is fast approaching, and with it comes the emergence of butterflies of all types.  The warming sun is already responsible for the first of four or five broods of Orange Sulphurs to be on the wing all over the refuge.  The last brood, like those in flight today, will winter over in chrysalis form and take flight early next spring. 
Orange Sulphur, Female (L) and Male (R)
Wherever there are open grassy areas or fields, you will see the mostly yellow Orange Sulphurs fluttering over the landscape in search of food, a potential mate, or a place to lay their eggs. Last week I was taking a photo of one that had landed, and as I usually do, I shot a burst of four photos in rapid succession.  I was surprised later to discover I had captured the moment that a female Orange Sulphur deposited a single egg on a leaf and left it to begin its journey to become a butterfly. 

In the first picture in the series, the butterfly’s abdomen is curled forward and touching the surface of the host plant leaf.  In the next shot, although somewhat out of focus, you can see the egg extruding from the tip of the butterfly’s abdomen.  This process is called ovipositing.  The third shot shows the butterfly flying off and you can just see the tiny egg standing up on the surface of the leaf.  The last shot is a close-up of the egg and the surrounding leaves.

Each Orange Sulphur lays its eggs one at a time on the upper surface of a leaf of a host plant – at Hagerman National Wildlife Refuge, these host plants are typically in the clover or pea family (including vetch).  When laid, the egg is white and spindle-shaped but will later turn crimson.  Each female has the potential of laying up to 700 eggs over its lifespan, so this process is repeated many times.  During the next 31 days, the egg will mature and hatch into a small dark green caterpillar with whitish stripes which will eat, grow, create its chrysalis, and emerge as the next generation of Orange Sulphur butterfly.

Orange Sulphurs are one of the most widespread and common butterflies in North America.  They flourish from southern Canada to central Mexico and are found in all of the “lower 48” states.  Although they are a joy to watch at the refuge, they are often considered a pest by farmers because the hungry caterpillars can inflict significant damage to fields of alfalfa.  In fact, in some places, the Orange Sulphur is referred to as the “Alfalfa Butterfly.”

The numbers of mature Orange Sulphurs is at its lowest point in February and March, but if not for changeable conditions and predation, just imagine how many could be produced over the course of a year.  In any case, as the seasons pass, you will see more and more of them all over the refuge, along with many other types of butterflies.  We recently confirmed the 60th species to be seen at Hagerman and more are likely to be out there.  Come visit the butterfly garden any time during the season and you are sure to see Orange Sulphurs and other species nectaring on many different types of flowers.

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