Tuesday, August 21, 2012

Evening Primrose

A Common Evening Primrose, Oenothera biennis, managed to establish itself beside the barn.  This is a native biennial that prefers growing in areas of bare, disturbed soil.  I always let one or two grow to maturity each year.  The seven foot tall plants produce an abundance of pretty flowers, but you have to be an early riser to see them at their best.

Evening Primrose is a night bloomer.  Flowers open in late evening and wither in the early morning sunlight.  Sphinx moths are common night time visitors to this flower.  I’ve spent several nights out watching and have yet to see any insect come near the flowers.  I haven’t stayed out all night, but there should be some nectar hunters out in the hour on either side of midnight.

In years past, I’ve seen plenty of sphinx moths at these flowers.  This year’s flowers seem to be incredibly lonely.  I wonder if the sphinx moths have gone the way of my missing butterflies.

Within a few hours after sunrise, the flowers have faded away.  The flower stalk keeps producing more flower buds.  There are always a few new buds ready to open every night, so the actual blooming period lasts for quite a while.  Old flowers are busy developing seeds.  Something must be fertilizing the flowers, because the seed pods just keep growing.

Ants have claimed this plant and have created a temporary nest at the base of the stem.

These small ants are on constant patrol and can be found everywhere on the plant.

Several Spittlebug nymphs are residing on the plant.  Most make their foamy nest near the stem on the upper side of the leaf.

Nymphs stay safely hidden within their bubble nests and feed on sap from the primrose. Each foamy mass contained at least two nymphs.  This is a dorsal view of two nymphs.  The right hand nymph is oriented head down and the left is head up.

The nymphs crawl free of their nest to perform the final molt into adulthood.  The adults are capable of flight and take off to pursue a free roaming life style.

The foam is apparently a tasty, but dangerous treat for many insects.  This ant and fly seem to have gotten stuck and perished in the sticky substance.  Even if the Evening Primrose didn’t have such nice flowers, the insect interactions alone would be worth having a few of the plants around.


  1. I was surprised to learn that there are two spittlebug nymphs in every foamy mass. I did some research on them for an article at my blog, but none of my other sources had mentioned this. Great photos of the nymphs and the new adults emerging from their nests.

  2. Two nymphs per "spittle" nest is not a general rule for all spittlebug species on all plants, and indeed, this seems unusual and interesting to me. The dead ant in the stickum appears to be a Myrmica sp.

    The ants building the tent at the base are Tapinoma sessile, and are most likely sheltering aphids. They and some other common ant species (e.g., Crematogaster spp.) do this on a wide variety of plants at this time of year.

    1. Update - Another look, and I misidentified that "Myrmica". Rather it's Tetramorium caespitum.

  3. Hi Deb and Bob. One is the norm for most Spittlebug species. I was expecting just one when I moved back the foam.

    Thanks for the ant ID, James. This is the first time I've found more than one nymph per nest, but I think it's also the first time I've ever exposed Spittlebug nymphs on Primrose. I did some searching and found a couple of anecdotal accounts of multiple nymphs per nest on Primrose. I also found a USDA paper on a pest species of Spittlebug on pine trees in western states that have multiple nymphs per nest.

  4. Hi Steve!
    I loved your picture of Oenothera flower!
    Is it free to be used?
    What should I do to use it?
    Thank you!!

  5. Marta - For photo use permission, email your request with details of intended use to bluejaybarrens@gmail.com