Pacific Beetle cockroach

The Pacific Beetle Cockroach (Diploptera punctata) extends its habitat from Asia toward Americas, reaching the Hawaiian islands. Not longer than 15mm to 25mm, as its common name suggests, it resembles a beetle. This is a viviparous species that gives birth to living offspring rather than eggs.Extensively used in university labs around the globe, this cockroach has been studied for many years; research aims to find new and effective ways to combat pest bugs.

As mentioned above, the offspring are birthed after a gestation of a few weeks (varying somewhat in response to temperature and food supplies) directly from the female’s womb, without the deposition of eggs or eggcase as many other roaches do.

As a quick note, reproduction is divided into four types: oviparity, false ovoviviparity, true ovoviviparity, and viviparity. In oviparity (with all families except Blaberidae), the ootheca is dropped shortly after it is completed, the female then leaves and has nothing more to do with the eggs. Initially, eggs have enough yolk to complete development, however water is obtained from the substrate to avoid dehydration.

In false ovoviviparity (almost all Blaberidae and four genera of Blattellidae), the ootheca is retracted into a uterus or brood sac after it’s formed, where it remains for the gestation period (e.g., Nauphoeta cinerea). The oothecal membrane is greatly reduced in the Blaberidae and less so in the Blattellidae. Eggs have enough yolk to complete development and obtain water from the mother during gestation.

True ovoviviparity (only the blaberide Geoscapheinae, specifically, four Australian genera: Geoscapheus, Macropanesthia, Neogeoscapheus, and Parapanesthia) differs from false ovoviviparity in that an ootheca is not formed. The eggs pass directly from the oviduct into the uterus or atrium, where they lie in a jumbled mass until birth. The eggs have enough yolk initially to complete development and obtain water from the mother as needed.

With viviparity (Diploptera punctata, Blaberidae: Diplopterinae), the very small ootheca is rotated and retracted into the uterus. It has only about a dozen very small eggs enclosed in an incomplete membrane; the larvae are quite large when born. At first, the eggs lack sufficient yolk and water to complete development, but during gestation the embryos drink “milk” and dissolved proteins and carbohydrates synthesized and transported by the mother’s uterus.