Which insect has yellow blood?

Science in dialogue

What color is the blood of insects, especially bumblebees, and why?

The blood of most insects, including that of bumblebees, is largely colorless. With a few exceptions, they lack the blood pigment, which is not only responsible for transporting oxygen in the body, but also gives the blood its color.

Instead, the insects supply their bodies with oxygen via a widely branched system of tubes. Through these so-called tracheas, the air gets into the immediate vicinity of all oxygen-consuming cells.

But not all insects can do without blood pigment. The mosquito larvae mainly breathe through their skin in the water. Some species live in oxygen-poor waters and have the dye hemoglobin in their blood for better oxygen supply. This also ensures the strong red blood of vertebrates. There are also other blood pigments with a different color. For example, some cancers, squids, and snails have blue blood. Your blood pigment is hemocyanin. The chlorocruorin of some worms makes their blood appear green. Other worms have purple blood thanks to haemerythrin.

The color depends partly on whether the blood pigment has bound an oxygen molecule or not. For example, oxygen-poor blood in our veins is dark red, while oxygen-rich blood in the arteries is bright red. Haemocyanin and haemythrin are colorless without oxygen.

Even without blood pigment, insect blood can sometimes take on a slightly yellowish to greenish color due to the pigments contained in vegetable food.

The question was answered by Prof. Dr. Hans-Jörg Ferenz, head of the insect physiology department at the Martin Luther University in Halle.