Do Butterflies Have Testicles?

Butterflies mate to increase their diversity and population. They have different genital organs, and people wonder if these small-sized insects have testicles. Scientists studied and examined the organs of male and female insects and concluded that the Lepidoptera species have a complex reproduction system.

Do Butterflies Have Testicles? Butterflies have testicles located in the abdomen and produce the sperms to mate and fertilize the eggs of the female butterfly. The color, size, and shape can vary among species because caterpillars usually have red testicles, while adults have transparent or yellowish testes with a spherical shape. These are fused and often appear as a single sac.

The genitalia of both genders from the same species are adapted to fit and lock into each other during copulation. Moreover, the male butterfly transfers nutrients along with the spermatophores to the female species and is often observed puddling in mud to gather energy and nutrients.

How many testicles do butterflies have?

They have two testicles but are fused and appear as a single structure. The ninth abdominal segment in male butterflies has these reproductive organs, but the position of the testes is different in the caterpillar stage.

People often wonder how butterflies mate without having prominent testes because they do not extend from their bodies. They start the fusion of two testes in their pupa stage; therefore, they do not look like two separate testicles.

However, you can notice the claspers at the end of the male species, which also serves as the gender identification sign. The testes of juno longwing butterflies are located dorsally in the middle of the abdomen.

They have a vas deferens thick tubular structure, connected to the testicles and ejaculatory tube to transfer the sperms from the testes to the aedeagus.

Moreover, I studied their testicles and the organs involved in reproduction because this topic drew my attention when I discussed it with my friend.

I read in a research theory that male butterflies also have internal reproductive organs known as accessory glands. They are specialized to secrete seminal fluids to help in sperm transfer and provide nutrients to the female while mating.

In addition, I also learned another fun fact about their reproduction. They use the ejaculatory duct to carry the sperm from the vas deferens, and its structure is a little bit complex in these insects, as this duct forms spermatophores.

The aedeagus is an organ like the penis and is located in the last segment of the abdomen. It extends out from its body, and the male inserts it in the female genitalia to deliver the sperm and the seminal fluid from accessory glands.

What color and shape are butterfly testicles?

The color and size of the butterfly testicles vary with species and age; for example, the shape is different in larvae or caterpillars than in the adult phase.

For example, some of them have yellowish kidney-shaped testicles, such as the passion butterfly, and the monarch caterpillar has dark red or pink testicles, looking like a single sac with four follicles.

Generally, the color varies from light yellow to transparent according to their developing stage. They appear spherical, while some species have slightly tubular-shaped testes with eight follicles.

They are small because the size of their testes depends on the species size, as larger butterflies will have slightly larger testicles than smaller ones.

Why do butterflies have testicles?

Male and female butterflies possess different reproductive organs, and these genitalia are essential for successful reproduction.

Males have testicles that are not prominent outside the body. They produce sperm in male insects and transfer the spermatophores to the females.

Their testes produce two types of sperm, such as eupyrene and apyrene, and they perform different functions in fertilizing the eggs.

One of my friends studied a lot about their reproduction and mating behavior.

Once, he told me that butterflies are involved in sexual reproduction, where the male has to fertilize the female eggs and then lay eggs on suitable host plants.

He said tests are essential for the overall biology of these insects because they cannot mate without these genitalia.

They cannot produce sperm without testicles; therefore, they have this significant organ in their reproductive system to ensure egg fertilization.

Moreover, he told me that their shape, size, and color can vary among species and their adaptations because there are approximately 20,000 butterfly species, and they all live in different habitats. These species are involved in various types of mating and courtship behavior.

When do butterflies start developing testicles and sperm?

They start developing their essential body organs in the larval or caterpillar stage. The sperm cells begin to differentiate and mature in the third and fourth caterpillar instar stage.

The testicles develop when the caterpillar hatch from the egg because it is the phase when the butterfly starts growing and developing all significant organs necessary for their survival in adulthood.

You can spot the bright red testicles on the underside of the caterpillar’s abdomen. The process starts with the mitotic and meiotic cell division, and the testes full of spermatogonia begin differentiation in the third instar larval stage, and the spermatozoa form in the fifth instar caterpillar stage.

The further changes in their reproductive organs occur in the pupa stage when the testes start fusion and look like a spherical ball with a single sac.

Their anatomy changes with each growth phase, and they come in the final shape after completing the metamorphosis.

Therefore, the shape and size of the testicles are different in different developing stages but are not prominent or clear enough to notice if you are a beginner in rearing butterflies.

How do testicles produce sperm in butterflies?

Testicles are specialized organs in their bodies to produce sperm, and the process starts right after they hatch from the egg and turn into a caterpillar.

For example, my neighbor works in a laboratory where a team of scientists worked to understand the anatomy of different insects.

He also had a degree in entomology and a vast knowledge of the reproductive system and adaptations involved for insects like butterflies.

Once, he told me that the spermatogonium cells undergo six mitotic divisions, and form leads to the production of 64 spermatocytes, which results in 256 sperms after two meiotic divisions and remain in this bundle until the testicles move them out.

Moreover, the last transformation of sperm cells occurs when the head develops with a specific gene, and DNA carries the genetic information.

In addition, he said the testicles in adult butterflies produce eupyrene and apyrene spermatozoa, which perform specific functions in copulation.

The eupyrene sperm cells ensure successful fertilization, while apyrene cells make sure the eupyrene cells fertilize the eggs and competition from other male species sperms.

Moreover, the eupyrene sperms stay in bundles during the copulation, while apyrene sperms disperse and do not remain in the cluster form when transferred to the female mating fellows.

The male fellows transfer the sperm packets in the spermatophores along with the nutrients, and according to the research, monarch butterflies transfer 10% of their body weight during copulation.

However, some species transfer 23% of their body mass. Therefore, they invest a lot of energy in mating and feed more to gather nutrients.

What changes occur in male butterfly reproductive organs after mating?

A team of researchers studied the changes in the male reproductive organs of butterflies after mating and the genitalia of virgin species.

They concluded that the simplex of virgin males does not change in length and transparency over time and age after eclosion.

Moreover, I read in this research paper that the male butterfly has reduced simplex length and yellow from transparent with granular fluids at the base end. However, the structures come in original size and color after mating.

They can produce more sperm over time, and the testicles again get filled, which increases the chances of mating for a second time.

Related Articles:

What is a butterfly exoskeleton made of?

Are Butterflies Attracted To Cleome?