June 19th. Eggs hatching.

 

First instar larva emerging from its egg.

 

June 24th Maturing first instar larva.

 

Possibly early second instar beside a late first instar.

 

June 28th. Second instar.

 

July 5th. Third instar.

 

 

 

 

 

July 14th. Fourth instar.

 

 

 

July 26th. Fifth instar.

 

 

 

Note the blue feet ("prolegs") on the abdominal segments and the oval "spriacles" on the sides of most body segments.

 

Closeup of a pair of prolegs. Note the "velcro" hooks that help it hang on. Prolegs aren't real legs; just muscular extensions of the abdominal body wall without segments. Insects only ever have 3 pair of true legs and they're on the thorax (just behind the head in caterpillars). The fundamental definition of an insect is 3 body regions (head, thorax, and abdomen), 3 pair of legs on the thorax, and in adults two pair of wings (on the 2nd and 3rd thoracic segments).

 

Closeup of head and thorax. You can see the 3 pair of segmented true legs.

 

Closeup of a spiracle. Spiracles are the external openings to the trachea or air tubes in each segment. Insects lack lungs and don't use blood to carry oxygen. Instead, the trachea branch into smaller and smaller tubes that reach directly to the body tissues. In this pic, the spiracle is closed (see the "slit" in the middle?).

 

August 4th. Photos of several of the largest caterpillars.

 

 

 

 

 

 

 

Click here to see an unrelated generation of caterpillars in 2010.