When the terms “sex” “mating” or “copulation” are mentioned, those various images and thoughts that flash through our minds are often pleasant and exciting. Unfortunately, for one animal the word ‘pleasant’ is definitely not the case, and in fact the poor female experiences the most traumatic insemination known. The ill-fated victim is the common bedbug (Cimex Lectularius).

Animal Kingdom

Image Source: Janice Harney Carr

Above Image: A Scanning electron micrograph  of the common bedbug (Cimex lectularius), digitally colorized with the insect’s skin-piercing mouthparts highlighted in purple and red.

The male bedbug is like no other – equipped with multi-functioning mouthparts serving two important purposes. The first is to pierce the surface of the skin of humans, in order to gain access and retrieve blood, a very common practice in parasites. The second is an evolved penis. This has adapted to a great design which allows easy piercing of the female’s abdomen in order to inject his sperm directly through the wound into her abdominal cavity. This brainy adaptation allows a closer delivery of sperm to the ovaries. From here, they diffuse through the female’s hemolymph, only having a short distance to swim to achieve fertilisation.

But then it gets worse…


Image Source: Rickard Ignell

Being pierced in the abdomen may not sound that bad, but the technique is very violent. The female is pinned down by the male and is often stabbed several times in the body to ensure successful insemination. This method has evolved to bypass the female’s genital passage, restricting and removing any control the female would usually have on the timing of her contraception. What a very disturbing method of procreation…

Painful sex that causes detrimental effects to health:

Yes, this method is extremely advantageous to successful insemination from males, but the traumatic process imposes great risks to females. The stress caused from insemination and open wounds, expenses the female of repairing the wound, stopping the leakage of blood and preventing the risk of infection.


Image Source: Armed Forces Pest Management Board

The female also needs to create an immune defence against sperm, and all together, requires a lot of energy whilst putting heavy strain on the body. This has resulted in decreased reproductive output, reduced lifespan and even death in females.

The female strikes back!

Female’s certainly do not sit dormant to this torment, and have in fact evolved a defensive counter-action of a pair of specialised reproductive organs at the site of penetration.  From observations during research, the scars left by the males on the female’s body can indicate the copulating position of the male. The results predict that the males pierce through the fifth segment of the female’s abdomen.

inseminationImage Source: Armed Forces Pest Management Board

So craftily, if the male stabs the right hand side of the female’s fifth segment, his spiked penis slides into a notch that directs it into a form of a holding pocket. These pockets are rich in spermicidal cells produced by the female, which allows her to kill both unwanted sperm and pathogens. Not all females can perform this, but those that have adopted this form of defence live longer life spans and produce more eggs.

And just when you think it’s all over…

Male bedbugs are beginning to learn about the females new defences, so are constantly on the watch for promiscuous females. Equipped with taste sensors on the tip of their penises, the male can detect any previous sperm deposits from other males, allowing the male to reserve his sperm and move on to those virgins!


Image Source: Janice Haney Carr

Above Image: Another Scanning electron micrograph shot of the mouthparts of a bedbug which
causes the most traumatic sex in the Animal Kingdom.

Now this is one very clever battle for sex, where the male and female are constantly forming adaptations either within their morphology or behaviour to achieve successful insemination and fertilisation.

Image Source: Aotearoa Pete

Creating a constant arms race – the male achieves better control to pass on those important genes, whilst the female is producing various techniques to resist being bred. The things animals will do for sexual selection!

  • Sue

    This is a brilliant article! Its quirky and just makes a great read!

  • gurpreet

    It is a great article with lot of information.