INSECT LIFE CYCLES:
How Knowing Them is A Real Buzz...

paper wasp, subfamily Polistinae, with nest

So, what do you see at the right? But before you look hard, let me tell you that the flower-like thing behind the wasp is just a plastic decoration on a neighbor's bathroom wall.

Maybe when you study the picture you see a paper wasp guarding her nest, and if you're really sharp maybe you notice the little eggs at the bottom of each nest cell. Now, here's what you missed:

THINKING IN TERMS OF LIFE CYCLES

Spittle Bug
SPITTLEBUG IN ITS SPIT:
The dark mass barely visible inside the above froth is an immature insect, a nymph, that later will metamorphose into an insect called a froghopper. Froghoppers are members of the True Bug Order, the Hemiptera, and the family Cercopidae. As the nymph sucks juice from the leaf, it spews out the spittle around it. The spittle keeps predators such as birds from eating the nymph, keeps the nymph from getting too hot or too cold, and keeps the nymph from drying out. See what both nymph and adult spittlebugs look like without spit at BugGuide.net

Let's think a little about the life cycle of the kind of wasp shown above.

Let's say that it's early spring. A female wasp like the one above has just emerged from winter hibernation, built the paper nest she's sitting on, and  laid eggs in the cells. When the eggs hatch she'll feed the larvae with prey she brings to them in their cells.

Eventually adult female wasps will emerge from the nest cells, and at that point the wasp in the picture will stop foraging, become a queen, and begin ruling her offspring, known as workers, by aggressively dominating them.

As a consequence of confrontations and aggressive interactions, each individual in the community will soon know who dominates them, and whom they can dominate. If the queen dies or is otherwise lost, the most aggressive worker takes over. This worker begins laying eggs and continues to dominate all below her.

As summer progresses, the nest is enlarged, more eggs are laid, more workers produced, and the queen dominates more and more workers. It's possible that an even more aggressive and powerful wasp from outside the colony will come,  overthrow the queen and become queen herself.

The wasp in the top picture, then, is preparing to set up a ruthless society of slaves that will be kept in line by force...

Here's the point I'm making by telling you the general life cycle of the above kind of wasp::

If you know basic life-cycle information about the various groups of insects, every time you meet an insect you'll understand much more about it than just what you see before you.

Though I'm not sure what genus and species the wasp in the picture belongs to, when I look at that picture I know the whole drama describe above is taking place because that's the typical story for nearly all members of the wasp subfamily Polistinae, the paper wasps. Since I know some general facts about paper wasps, when I meet a particular paper wasp, I already know specific facts about it, even if I've never seen that particular wasp before.

So that's how knowing life cycles is so much fun. Now the question is, "How do you learn life cycles?"

LIFE CYCLES IN FIELD GUIDES

Nearly all good field guides are organized so that closely related organisms are considered together -- all wasps in these pages, all bees in those pages, etc. Moreover, each section of such field guides usually provides basic facts about the life cycles of the organisms covered there.

Here's an example. I go to my A Field Guide to Insects : America North of Mexico and read about members of the order Hymenoptera, superfamily Apoidea, family Apidae, subfamily Apinae, tribe Bombini (in other words, the Bumble Bees), and I read that most Bumble Bees nest in or on the ground, often in deserted mouse nests. Generally Bumble Bee colonies die when winter comes, with just the queens overwintering and starting new colonies in the spring.

Beyond that, knowing that all bees are members of the order Hymenoptera, I automatically also know that Bumble Bees produce eggs that hatch into larvae, which develop into pupae, which metamorphose into adults -- because all members of the Hymenoptera undergo complete metamorphosis. Knowing that Bumble Bees are members of the family Apidae, I automatically know that Bumble Bees have long, slender glossa (tongues) useful for getting to nectar in the bottoms of flowers -- because all members of the Apidae have long, slender glossa...

Another approach is to think evolution-wise.

THINKING EVOLUTION-WISE

On our Evolutionary Trees page we make the point that evolving life proceeds more or less like a tree that starts as a single sprout, and branches, and then the branches branch, and so forth, with the branches growing at different rates, and branching with various degrees of vigor. One offshoot of this fact is that the species of any particular "branch" share many traits -- traits they've inherited from a common ancestor. The insect world (which is a branch of the arthropod branch of the elocutionary tree) is huge, and it itself divides into many branches. Each insect order is a branch, and each of those branches has branches itself, which are families... and of course those branches are branched, too, into genera and species.

Here's a nice chart, which comes close to being an upside-down evolutionary tree for the insects. In other words, you can think of "the dawn of insect life" as being at the top of the chart, with each branch in the insect tree representing a major evolutionary advance millions of years later.

life cycle facts for various insect orders

So, at the chart's top we see that one of the first very important innovations to evolve in the insect world was that of acquiring wings. The wingless orders are considered to be most like the very first insects of about 400 million years ago. Winged insects didn't come along until around 300 million years ago.

The second big "invention" among the insects involved the ability to fold their wings over their bodies when not in use. The most recent "insect invention" was the evolution of "complete metamorphosis." This innovation has been such an advancement, that, as the chart says, most insect species alive now belong to this group! One reason complete metamorphosis is so great is that the pupa resting stage is typically well camouflaged, plus the pupa's hard husk protects the developing adult form the outside world.