Head spicule

Some aphids have minute spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
on the surface of their headshead:
The first or most anterior region of the body, bearing primary sense organs.

Spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
give an aphid's headhead:
The first or most anterior region of the body, bearing primary sense organs.
a rugoserugose:
Roughened or bumpy. Opposite of smooth. See also scabrous.
appearance. Most species do not have them, whereas others have them either dorsally on their headshead:
The first or most anterior region of the body, bearing primary sense organs.
or both dorsally and ventrally.

Faint spicules

Dorsal spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
. Focus up and down on the specimen to see if the spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
are present ventrally, as well as dorsally.

The spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
on the right side of the headhead:
The first or most anterior region of the body, bearing primary sense organs.
have been darkened for emphasis. Note also the developed diverging antennal tuberclesantennal tubercle:
An extension of the head near the medial margin of the antennal socket.
. Head spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
are typically found on aphids with antennal tuberclesantennal tubercle:
An extension of the head near the medial margin of the antennal socket.
, especially those that are parallel or converging.

Prominent spicules

Spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
can sometimes be quite conspicuous.

These head spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
are quite conspicuous, darkened for extra emphasis. Note also the converging antennal tuberclesantennal tubercle:
An extension of the head near the medial margin of the antennal socket.
.

Spicules absent

The absence of spiculesspicule:
A small, sharp projection of the cuticle. See head spicules.
makes the aphid headhead:
The first or most anterior region of the body, bearing primary sense organs.
appear smooth.

Note the smooth, diverging antennal tuberclesantennal tubercle:
An extension of the head near the medial margin of the antennal socket.
.