The problem with the German cockroach (Blattella germanica) is that its origin remains mysterious. It is now the dominant cockroach species worldwide, found only in human habitats, where it has been shown to displace other cockroach species due to the increased use of central heating and to the ability of B. germanica to develop resistance to insecticides (Stejskcal and Verner, 1996). The species has never be found in natural habitats and its original range is unknown.

According to Rehn (1945), it was first identified during the Seven Years' War (1756-1763) when the Russian and Prussian combattants gave it the name of their opponents (Prussian cockroach and Russian cockroach respectively). Lucas (1920) says that the insect moved to the British Islands in the first half of the 19th century: there are mentions of it being "abounding in some houses" in 1822, well before it was (allegedly) imported as a stowaway by British soldiers returning from Crimea in 1857. Rehn formulated the hypothesis that the insect was originally from North Africa, brought by Mediterranean traders to the Black Sea and Asia Minor, and later imported from southern Russia to Western Europe through commerce and war. According to Rehn, this path had already been followed by the Oriental cockroach Blatella orientalis in the preceding decades. A more recent hypothesis (Tang et al., 2019) is that B. germanica was brought from Asia and arrived in Europe during the Seven Years' War. This hypothesis is mostly based on the morphological closeness (and interspecific breeding in one case, though with sterile offsprings) of B. germanica with Asian species. However, there is no wild population of B. germanica in Asia, so there is no definite answer.

But were cockroaches known to Europeans before the arrival of the invasive "German" one in the mid-1700s? This is where the plot thickens. I will only tackle here the European side of the story. On the American side, there would be a lot to say using Spanish and North American sources (featuring John Smith of Pocahontas fame) but it's already long.

Part 1. Classical Cockroaches

As reviewed by Baevis (1988), there are numerous citations of coackroach-looking insects in Greek and Latin texts, though it is difficult to ascertain that the authors are actually talking about cockroaches, let alone about a specific cockroach species. Indeed, in 1870, a reader of Nature, in a letter discussing cockroaches in ancient texts, already complained that it was "very difficult to identify with absolute certainty the insects mentioned in classical authors" (Robinson, 1870). A potential candidate is the silphes (ςίλφη), a pest insect alluded to by various Greek authors including Aristotle, Aristophanes, Aetius, Lucian, Aelian, Galen, and Dioscorides. Latin texts, notably Pliny, but also Horace, Martial etc., often mention the blattae, the word from which are derived the insect order blattodea and the cockroach genus blattella in taxonomy, as well as the vernacular name blatte in French.

In some cases, the description matches more or less that of the cockroach: it is an insect pest that lives in the habitations, often in bakeries and humid places like bath-houses and privies, that is foul-smelling, and avoids light. The latter property, observed by anyone who has ever switched on the light at night in a cockroach-infested kitchen, is mentioned for moralistic purposes in religious texts such as Augustine's Contra Faustum Manichaeum, where the Christian author opposes the flies attracted by the light to the cockroaches fleeing the light (muscas lucipetas, et blattas lucifugas, XIX, 24). The latter, says Augustine, are born in "obscure chambers" (obscuris cubiculis). Augustine, of course, was a Berber native from what is now Algeria: one of the major cockroach species, Blattella orientalis, is thought to originate from North Africa. Older translations of Augustine tends to ignore the term blatta, rendering it as "moth" (French translation and English translation).

Some other citations concerning silphes and blatta are poorly conclusive. The insect could be a silverfish (Lepisma saccharinum), for instance when it is cited as destructive to books in Evenus and Lucian (Houghton, 1870), a cricket, or a (stinking) darkling beetle (Blaps spp.). Dioscorides says in De materia medica (II, 38) that

the inside of the silphes found in bake-houses when pounded with oil is good for pains in the ear.

Latin versions of Dioscorides translate silphes either as blatta or grillo (cricket). A French version of 1559 translates it as mill cricket, ie the house cricket Acheta domesticus. It even adds a commentary comparing it to its field relative Gryllus campestris, noting how the house cricket "hates light". Achetus domesticus is another invasive species with a disputed origin and a large gap between its mentions in classical texts and its appearance in Europe in the Middle Ages (Kevan, 1991).

Pliny the Elder gives a relatively extensive description of the blatta, first in book XI, 34 (in Latin). Categorized as a beetle, the blatta is known

to seek dark corners, and to avoid the light: it is mostly found in baths, being produced from the humid vapours which arise therefrom.

He goes on to describe another type of blatta whose burrowing behaviour is more typical of a solitary wasp or other hymenoptera than of cockroaches.

In Book XXIX, 39, Pliny describes three types of blatta that can be used to make remedies once boiled in oil and ground: a soft one (blatta mollis), one that is found in mills (myloecos), and a stinky one with a pointy butt (blatta odoris taedio invisa, exacuta clune).

According to Beavis, classical sources include very few mentions of insecticidal preparations against cockroaches:

Pliny, however, does make mention of two herbs, one named after the insect (blattaria), which when thrown down on the floor were said to draw together all the cockroaches in the house so that they could be conveniently disposed of (XX.171, XXV.108). The cockroach was also considered important by beekeepers, being listed among those pests infesting hives (Virgil G. IV.241-3; Columella RR IX.7.5; Palladius RR 1.37.4): yearly fumigation was recommended to combat such pests.

So that's it for classical sources: they describe several insects, including some that fit the description of cockroaches: uniquely "domestic" and scurrying away when someone switches on the light lights a candle. Because some of these authors were living in North Africa or around the Mediterranean sea, it is credible that they would be exposed to North African species, namely Blattella orientalis. It should be noted here that cockroaches go through several instars until reaching their adult form, so we cannot rule out that the different "species" of cockroaches observed by classical authors were actually different instars of the same species.

->Part 2. Modern European Cockroaches