10 facts about the dangerous and hard-to-kill German cockroach that is raging in Vietnamese apartments

German cockroaches have many different characteristics from regular cockroaches: they are smaller, have elongated bodies, have quite tall legs, cannot fly, run very fast and they are 'resistant' to insecticides.

The German cockroach (Blattella germanica) is an exotic cockroach that measures about 1.3 - 1.6 cm in size when fully grown. Initially, scientists mistakenly thought that the German cockroach came from Europe, so they named this species the German cockroach. However, they later found evidence that the German cockroach came from Southeast Asia.

German cockroaches (left) are smaller than regular cockroaches (right).

German cockroaches are found in almost every corner of the Earth except Antarctica. Unlike Asian cockroaches that prefer to live outdoors, German cockroaches are not able to survive well in the wild, so they choose to live in places where people live.

This species of cockroach eats and gnaws on everything from food, soap, leather, books, toothpaste to plastic packaging. When it runs out of food, this species of cockroach is even ready to turn to cannibalism.

German cockroaches reproduce faster than any other house cockroach species, taking only 50 to 60 days to develop from egg to adult and capable of reproduction. In just one year, a pair of German cockroaches can produce 10,000 offspring. The young cockroaches feed on the adult's waste and molt to grow. German cockroaches are mainly nocturnal.

Here are 10 facts not everyone knows about this dangerous German cockroach.

1. German cockroaches have incomplete metamorphosis, with only 3 phases in their development.

2. German cockroaches are vectors for the transmission of salmonella and other diseases, and cockroach droppings have been linked to an increase in eczema, irritation, and asthma attacks.

3. The hard protective shell behind the head (pronotum) of the German cockroach has two dark stripes, running parallel from the back of the head to the cockroach's wings.

4. German cockroach eggs contain 35 to 40 baby cockroach larvae.

5. German cockroach eggs take only one month to hatch if conditions are favorable.

6. Female German cockroaches will always carry the egg sac with them until they are about to hatch, then release it to avoid predators.

7. It takes a German cockroach anywhere from 6 weeks to 6 months to mature, depending on food source.

8. German cockroaches rarely fly but prefer high places (apartments) with high temperatures and humidity.

9. German cockroaches can climb smooth surfaces thanks to the arolium texture on the soles of their feet.

10. German cockroaches have a pale patch in the middle of their thorax in the nymph stage.

German cockroach droppings look like peppercorns.

Some ways to kill German cockroaches:

Clean the house thoroughly, making sure there is no standing water or leftover food.

Pay attention to gaps such as kitchen cabinets, under the refrigerator, under the microwave, etc. If you find German cockroach droppings, look for their eggs around that area and destroy them.

Use hot glue to cover gaps in walls, doors, etc.

Use insecticides but be careful to follow the manufacturer's instructions to avoid affecting human health.

Jessica Tanner

Update 26 May 2025