Insect Mating and Sexual Behaviors

Insects are very interesting creatures. Yet, we seem to take them for granted. Maybe because they are often tiny and inconspicuous. I’ve learned from my mother (who takes special interests in aquatic insects) that insects are very important to the food chain, hence to the balance in nature. Aside from this, some have very interesting behaviors, which would put us humans to shame. Here are some of the facts I have encountered while browsing through my mother’s notes.




Do you know that SEX is not a necessity to insects? This is because some insects exhibit parthenogenesis or egg production without sexual fertilization (i.e. aphids), while one species of coccid exhibit hermaphroditism or self-fertilization of eggs. We humans might think, where’s the fun in these activities? Well, unlike humans, insects use instinct in order to cope with the realities of life. Reproducing without sex is quite advantageous. For some insects, having sex will cost them a lot, such as:



Cost of meiosis – this means sacrificing half of the genotype
Cost of recombination – may result to dangerous or lethal homozygosities (abnormalities and death)
Cost of mating – time and effort in finding a suitable mate
Cost of producing males – when in fact a parthenogenetic female is likely to produce twice as many daughters and four times as many granddaughters as the average sexual female

But again, not having sex could be boring even to insects. So, most insects still use sex in reproduction. Why? What are the advantages of having sex? READ ON HUMANS AND LEARN! Having sex in reproduction is not only fun but more importantly results to diversity or “variable” offspring, which may be better able to survive in the “new” or changing environment.

Insects are quite wise (it makes me wonder, are we descendants of insects?). They have pre- and post-mating strategies to enhance chances of successful mating. Here are some unique strategies (I don’t know if we humans can adopt these strategies):

Mosquitoes practice female monogamy induced by male accessory gland substance – after mating, male mosquitoes secrete a hormone that reduces the sexual receptivity of the just-mated female

Dual function of the damselfly penis, which are sperm removal and transfer – transfers sperm and removes sperm deposited by ‘preceding’ male

damselfly penis

Male bedbugs (Afrocimex spp.) possess structures that mimic female genitalia – rival males who mount these “female mimics” just waste their sperm

Many species exhibit prolonged copulation (a form of mate guarding) such as the damselflies and dragonflies

Enallagma exulans in copula

Of course, like humans, insects also undergo a period of courtship before mating. Here are some of the “devious” ways on how the male insects choose and catch the attention of the females.

Adaptive female-mimicking behavior in a scorpionfly – males use prey in courtship è offers prey to a female, then (if she accepts) mates with her; male strategies to obtain prey:

Some steal prey from other males (‘victims’ must wait longer before copulating)

Deceptive transvestism – some males act like females (landing near another male that has a prey item & lowering wings as receptive females do) to obtain a prey item

Choice for high fecundity or fertility – male tend to choose larger females; larger females can often produce more eggs and offspring (e.g., mormon crickets)

Female chooses males with increased fecundity, (may select males that court most vigorously, since ‘vigor’ is correlated with sperm supply)

You can be amazed by the criteria an insect sets in choosing a mate. Here are some of the “surprising” facts about an insect’s choice for immediate gains and/or parental ability:

Females tend to accept only males with insect prey above a certain size; possible benefits of such a preference
Male mates while female eats, so a larger insect means that female eats longer, therefore, copulation is longer & this helps ensure fertilization of eggs

More food from a male means less hunting by the female; less hunting means a reduced risk of being caught by a predator (i.e., spider's web)

Males that bring larger prey may be of higher quality

Now tell me, does size really matter? Definitely not when it comes to mating, courtship and sex. Look at the amazing style of these tiny insects. After reading this Blog, I’m sure you will never take insects for granted. In fact you may look at them with awe.