Aphids are small insects, a few millimeters in length, with piercing sucking mouthparts. They are soft bodied and generally pear shaped with two protruding tubes called cornicles extending off the posterior dorsal part of their bodies. The cornicles can emit alarm pheromones when they are disturbed. Aphids can be winged or wingless and have a very complicated lifecycle. Females can produce males or females without mating and give live birth or reproduce by mating and laying an egg. The reproductive cycle is often dependent on the environmental factors around the insect.
Life Cycle - Aphids overwinter as eggs and in the spring the female that hatches out is called the fundatrix or stem mother. This female aphid reproduces asexually (without males) and several generations reproduce this way through the spring and summer. In the fall both males and females are produced. The females are fertilized by the males, then go on to lay the overwintering egg. Although not pictured in this life cycle image aphids can also produce winged phenotypes. This is usually triggered when a plant becomes overcrowded and winged types are produced that can migrate to other host plants.