What term describes insects that retain eggs in their body until they hatch?

The term that describes insects retaining eggs in their body until they hatch is "ovoviviparous." This reproductive strategy combines characteristics of both oviparous and viviparous methods. In ovoviviparous organisms, the eggs develop inside the female's body, and once they are ready to hatch, young are born alive rather than being laid as eggs. This adaptation allows the young to be better protected from environmental threats and increases their chances of survival once they are born.

In contrast, the other terms refer to different reproductive strategies. "Viviparous" refers to organisms that give birth to live young that develop internally, but it typically means the young receive nutrients directly from the mother, rather than from eggs. "Oviparous" indicates organisms that lay eggs outside their body where development occurs. "Alloparous" is a less common term and does not refer to a recognized reproductive mode in insects. Therefore, "ovoviviparous" is the most accurate term for describing insects that keep their eggs inside until they hatch.