This question came in to me through my Twitter and I thought it was so interesting! Yes insects can and do taste. Yes it’s different than smelling for them. But do they actually have taste buds?

What’s the Difference Between Smelling and Tasting

The two are pretty similiar. Both smelling and tasting rely on chemo-receptors that make sense of the world around you. Besides the placement of the receptors the specific receptors responsible for smelling and tasting are different and the types of of chemicals they recieve are also different (odorants and tastants). Humans – we smell with our noses and taste with our tongues but insects smell with their antennae and taste with specialized structures associated with the mouth called “maxillary palps.” And also sometimes their feet. And also sometimes some other random body parts.

Insects do smell and taste and the sensation is different. We’re not exactly sure what the insect experiences when they are tasting vs smelling but behavioral studies have shown us that they are are different. If the insect is picking up airborne volatiles we say that they are “smelling”. If they come in direct contact with it – like a fly landing on your pizza – we call it “tasting”. If you want some fancy words to throw around, insect tasting is technically referred to as contact chemoreception or gustatory chemoreception.

Why Do Insects Need to Taste?

For the same reason you do! To know what they’re about to shove in their mouth is edible. But sometimes tasting allows butterflies to know if a plant she’s landed on is suitable for her eggs. And same thing with flies but usually it’s to determine if the rotting organic matter is good enough to lay eggs on or the adult just wants to take a nibble. Mmm pizza …

Insects can taste sugar, salt, acids, and bitter tastes however only sweet things seems to catch their fancy, but it does also seem to be concentration dependant. For example, fruit flies are attracted to salt at low concentrations and deterred at high concentrations. Not all that different from us.

Insect’s sense of taste is very sensitive too! Honey bees can detect concentrations of sugar that are undetectable to us. And they aren’t a fan of splenda either and can’t be tricked into eating artificial sweeteners. (To be fair, I can’t either.) They also have specific taste receptors that can distinguish different types of sugars. Insects probe or taste test the food that they’re considering to see if its worth it for them to eat, their young to survive on, or to bring back to their colony.

Okay Cool – They Taste. But How? Exactly?

Insects are covered in hairs. From their wings, to their legs, to their face. Some of these hairs are just to keep the insect warm or to detect motion. Some of these hairs are responsible for smelling (coeloconic sensilla [food] and trichoid sensilla [pheromones]), and others are responsible for tasting. These hairs are thick walled hairs set into a pit where chemicals can enter. These are called “pegs” or more technically, uni-porous sensilla. These pegs can be found on different parts of the body including the mouth area but also on the insect’s feet! If the insect is walking on something tasty their tongue will stick out which is called the tarsal taste and proboscis extension reflex. Drosophila even have taste receptors on their wing margin and some taste receptors are found on parasitic wasps’ ovipositors (the structure that lays eggs into the host).

Basiconic sensilla (hairs) are on the maxillary palps and these are responsible for tasting sugar. Basiconic sensilla are also found on the antennae but are responsible for mainly detecting carbon dioxide. In most insects this detection of CO₂ tells the insect to get out because a mammal is looming. Except for mosquitoes. Those just “bee-line” it to you to get a sample of your sweet, sweet, mammal blood. Anyway – I digress. When these basiconic sensilla are on the mouthparts and detect CO₂, the opposite response is elicited and the insect is attracted to it. Because CO₂ means fermenting. And fermenting means sugar. And sugar – is well – delicious.

Gr family genes are responsible for making these tasting pegs and we can find different genes of this family expressed in tarsi (last leg segments), the proboscis, in mouthparts, the antennae, and sometimes in the ovipositor.

TL;DR

Insects can taste. They taste the same things we do – sweet things, salty things, acidic things, and bitter things but are really only attracted to sweet things. They have thick hairs called pegs that end in a pore instead of taste buds like humans have, but the net result is basically the same. When a substance comes in contact with these hairs the insect can taste it. Sometimes these hairs are found on funny places. Not just the mouth like you’d expect, but also antennae, legs, and even the egg laying organ in some wasps.

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References

1. Hallum EA, Dahanukar A, Carlson A. 2006. Insect odor and taste receptors. Annual Review of Entomology 51:113–35.
2. Hay P. 2015. “Do Insect Have Good Taste?” Know How Know Now: University of Nebraska Extension.
3. Kim H, Choi MS, Kang K, Kwon JY. 2016. Behavioral Analysis of Bitter Taste Perception in Drosophila Larvae. Chemical Senses 41(1): 85-94.
4. Yarmolinsky DA, Zuker CS, Ryba NJP. 2009. Common Sense about Taste: From Mammals to Insects. Cell 139(2): 234-244.