Nymph or Larvae?

What’s the difference between a nymph and a larva? For years, I’ve heard both terms but hadn’t given it much thought. This year, I started photographing insects earlier than I have in the past years and as I was trying to identify some of the grasshoppers, I noticed they didn’t have wings. Call it either an AHA! moment or a DUH! moment, or both – either way, I realized these were nymphs! I was hooked and I wanted to know more.

Nymphs and larvae are both immature insects; the difference is their life cycles.  Insects undergo one of 3 types of changes as they mature: 1) ametabolous metamorphosis, 2) hemimetabolous metamorphosis, or 3) holometablous metamorphosis. Depending on which type of maturing process the insects go through depends on what the immature insects are called.

A nymph is the immature stage of insects that mature via a process call hemimetabolous metamorphosis or incomplete metamorphosis. It means the babies generally look like the adults, only in a smaller version. They grow by molting and each molt is called an instar. The one exception is for dragonflies and damselflies; their nymphs are called naiads. Some of the insects that age using this process are grasshoppers, mayflies, and plant bugs.

Grasshopper - Green legged  (5)
Green-legged Grasshopper Nymph
Photo by Marci Hess

Remaining exoskeleton from a recent molt.
Photo by Marci Hess

A larva is the immature stage of insects that mature via holometablous metamorphosis or complete metamorphosis. Larva are usually wormlike in appearance and have no resemblance to the adult they will become; we mostly refer to them as caterpillars. The grow by molting, eventually becoming a pupa, then the last molt is when the insect changes to the adult form. Some of the insects that age using this process are butterflies, beetles, and moths.

Salt Marsh Caterpillar (2)
Larva of a Salt Marsh Moth
Photo by Marci Hess

Salt March Moth
Photo by Marci Hess

Lastly, is ametabolous metamorphosis. This is where the insect grows to adulthood with little change in body form. If you’ve ever wondered how aphids can accumulate so quickly, this is why – they give birth to live young who can reproduce in a matter of days.

Aphids – notice the various sizes
Photo by Marci Hess

I’m grateful that my curiosity kicked in! I was much more familiar with the larva term than I was the nymph term…at least until I met Jim. We now both do “nymphing” — his is with a fly rod and mine is with a camera!