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The galls occur when female aphids lay a single egg on the underside of the sumac leaf, inducing the leaf to form a sac over the egg. [5] According to Hebert et al, the eggs "give rise to a series of parthenogenetic generations, which remain within the gall. Winged females leave the gall in late summer and fly to moss, where they establish ...
A female aphid lives for 9 to 25 days and can produce from 25 to 125 young during its life. There may be up to twenty generations in the year. By November winged forms have developed and eggs are laid before winter sets in. [6] In warmer climates, parthenogenetic reproduction takes place throughout the year.
Aphid giving birth to live young: populations are often entirely female. In autumn, aphids reproduce sexually and lay eggs. Environmental factors such as a change in photoperiod and temperature, or perhaps a lower food quantity or quality, causes females to parthenogenetically produce sexual females and males. [56]
The production of female offspring by parthenogenesis is referred to as thelytoky (e.g., aphids) while the production of males by parthenogenesis is referred to as arrhenotoky (e.g., bees). When unfertilized eggs develop into both males and females, the phenomenon is called deuterotoky. [22]
The aphids migrate back to primary hosts in August and overwinter as eggs on weeds. In North America they are heavily parasitized by the braconid wasp Aphidius nigripes , which lays its eggs in the aphid nymphs, and these are eventually killed by the wasp larvae developing inside them.
The gall is green at first, then turns bright red. This gall, rich in nutrients, provides both food and shelter for the female aphid. Gall's interior Witch Hazel Cone Galls. H. hamamelidis have three generations per year, each with a different part in the life cycle. At the start of spring, females or stem mothers crawl to witch-hazel leaf buds.
Aphidius wasps are endoparasitoids of aphids. The female wasp lays eggs in an aphid. When the eggs hatch, the wasp larvae feed on the inside of the aphid. As the larvae mature, the hosts die and become slightly enlarged or mummified, often becoming tan or yellow. Complete metamorphosis occurs within the host.
The fundatrix, or parthenogenetic female aphid produced on the primary host plant from an overwintering fertilized egg, is pale green; these individuals allow the second generation alatae to form within the gall. [5] The galls typically mature in late August to early September and change color from green to red over the course of maturation.