The bumblebee body

The links on the left will take you to pages about specific parts of the bumblebee body, for a general overview you might like to read this page first.

Skeleton.

As with all insects the bumblebee has what is called an exoskeleton, i.e. its skeleton is on the outside and is made up of hard plates of chitin. Chitin is a nitrogenous polysaccharide insoluble in water, alcohol, dilute acids and digestive juices. So having an exoskeleton means that once a bumblebee has hatched out of its cocoon as an adult it cannot get any bigger. The muscles are attached to the inside of the plates. Humans have an endoskeleton, i.e. our skeleton is on the inside of our body and is made of bone. The muscles are attached to the bone, and because the skeleton is inside we can grow in size.

The bumblebee's body has many adaptations to enable her to gather nectar and pollen more efficiently from flowers, to operate in temperatures that stop other pollinators working, and to defend herself and her nest mates.

Bumblebees would die without flowers and many flowers would be unable to breed without bumblebees. Like most insects the bumblebee body can be divided into three main areas:

1) the head with the eyes, mouthparts and antennae
2) the thorax with the wings, wing muscles and legs
3) the abdomen which contains the digestive and reproductive organs and sting

Wings

Bumblebees have two pairs of wings, though it looks like they have just one pair as the wings operate together, unlike those of dragonflies, and are held together by a series of hooks. For more details on wings, wing beat, flight speed etc go to the wings page.

Antenna

The antenna (see below) or feelers of the bumblebee are used rather like humans use their noses, and are also used for touching. Again there are more details on the antenna page.

Tegula

The part where the wings join the thorax is called the tegula (plural tegulae) When marking bumblebee you must be very careful to keep the tegula clear.

side view of bumblebee body showing the body parts

bumble bee antenna through an electron microscope

Legs

Like most adult insects the bumblebee has three pairs of legs. Queen and worker bumblebee legs are specialised for gathering pollen, and there is a lot more about legs on the leg page.

Eyes

Like many adult insects the bumblebee has two compound eyes and three "primitive" eyes called ocelli (see the photographs on the left and below). To find out more about eyes and bumblebee vision go to the eye page.

Breathing

The bumblebee breathes through spiracles, these are simply paired holes down the side of its body, see the drawing above. The air is drawn in as the insect moves. The spiracles are attached to tubes called trachea, the bumblebee also has air sacs.

Male, female or queen.

As far as the external body goes queens and females are more or less the same, although in some species there is a big size difference, and there may be some difference in hair colouring. But as this section is not concerned with species we will lump queens and workers (females) together. So the differences between males and females are:

3. Rear leg. Females have a shiny, flat pollen basket fringed with long hairs. In fact any bumblebee carrying pollen will be a female, as males and cuckoos do not have a pollen basket.
2. Antennae - the male has 13 segments and the female has 12. The antenna on the left is from a female.
3. Abdomen. Females have 6 segments (see the drawings above), and males have 7. However this is very difficult to see in a live bumblebee because of the hairs.

Sex determination.

In bumblebees and other social Hymenoptera (bees, ants and wasps) fertilized eggs develop into females (queens or workers), and unfertilized eggs develop into males. For more on this see the Haplodiploidy page.

Tongue

The bumblebee tongue is specialised to suck up nectar (see the photograph on the right). At rest or when flying the tongue is kept inside a sheath and folded under the head and thorax.

Abdomen

The abdomen is covered with dorsal tergites and ventral sternites numbered 1 - 6. Wax is secreted between these plates.

Wax

Wax is secreted by the queen when she starts the nest, and by workers on the second day of adulthood. The secretions decline after a week. It is during this time that most workers spend most of their time in the nest performing household tasks. Only later do they leave the nest for the dangerous job of foraging.

Hearing

A bumblebee does not have ears, and it is not known whether or how a bumblebee can hear sound waves passing through the air, however they can feel the vibrations of sounds through wood and other materials.

Heart

The heart, like that in most other insects, runs down the entire length of the body.

Fat body

The fat body is a nutritional store. Before hibernation queens eat as much as they can to enlarge their fat body. The fat in the cells is used up during hibernation. The fat body is largest in queens, smaller in workers, and doesn't exist in males.

Blood

The blood (hemolymph), is not carried in veins and arteries as ours is, but just sloshes around. The body organs, heart, muscles, etc. sit in a pool of blood. The heart does pulse blood through its long tube, though, so there is a circulation of sorts.

Inner organs

In fertilised queens the ovaries are activated and when the queen lays an egg it passes along the oviduct to the vagina. In the vagina there is a container called the spermatheca. This is where the queen stored sperm from her mating. Before she lays the egg she will decide whether to use sperm from the spermatheca to fertilise it or not. Non-fertilised eggs grow into male bumblebees, and only fertilised eggs grow into females and queens.

Hormones

As in all animals hormones play a big role in the growth and development of the bumblebee. The hormones that stimulate the development of the ovaries are suppressed in the other female worker bees while the queen remains dominant.

Salivary glands

Salivary glands in the head secrete saliva which is mixed with the nectar and pollen. Saliva is also mixed into the nest materials to soften them.

Metabolic rate

It is often thought that humming birds have the highest metabolic rate of all animals, however the metabolic rate of bumblebees is 75% higher than a humming bird's!

Bombus lapidarius male bumblebee showing ocelli, tongue and moustache