9.16: Insect Food
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How do butterflies eat?
You might have seen butterflies searching for food on a flower before. They have long, tube-like mouthparts that can reach deep within a flower. The butterfly uses this mouth-tube to siphon nectar from the flower, as if sucking through a straw.
What do insets eat? Practically anything they want. There are so many different insects, that among all of them, no potential food is safe. Lots of insects eat plants, some insects eat other insects, and some even drink blood. Many insects eat nectar from plants. And some insects will eat whatever scraps of food you leave lying around.
A few insects, such as mayflies and some moths, never eat. That’s because their lives are over in just a few hours or days. Once these insects become adults, they lay eggs, and then die. On the other hand, some insects are very healthy eaters. A silkworm eats enough leaves to increase its weight more than 4,000 times in just 56 days, as the silkworm increases in size about 10,000 times since birth. A locust eats its own weight in plants every day. Just imagine eating your own weight in food every day. You probably couldn't. You would most likely get very sick even if you tried.
How do Insects Eat?
Insects eat in many different ways and they eat a huge range of foods. Around half are plant-eaters, feeding on leaves, roots, seeds, nectar, or wood. Aphids and leafhoppers suck up the sap from plants. Praying mantises are predators, hunting other small creatures, including insects like moths, caterpillars, flies, beetles, and spiders. Insects like mosquitoes and aphids have special mouthparts that help them pierce and suck. Others, like assassin bugs (Figure below) and certain species of female mosquitoes, eat other insects. Fleas and lice are parasites, eating the flesh or blood of larger animals without killing them.
Insects have different types of appendages (arms and legs) adapted for capturing and feeding on prey. They also have special senses that help them detect prey. Furthermore, insects have a wide range of mouthparts used for feeding.
Examples of chewing insects include dragonflies, grasshoppers, and beetles. These insects use one pair of jaws to bite off bits of food and grind them down. Another pair of jaws helps to push the food down the throat. Some larvae also have chewing mouthparts, as in the caterpillar stages of moths and butterflies (Figure below).
Some insects use siphoning, as if sucking through a straw, like moths and butterflies. This long mouth-tube that they use to suck up the nectar of the flower is called a proboscis. Some moths, however, have no mouthparts at all. Some insects obtain food by sponging, like the housefly. Sponging means that the mouthpart can absorb liquid food and send it to the esophagus. The housefly is able to eat solid food by releasing saliva and dabbing it over the food. As the saliva dissolves the food, the sponging mouthpart absorbs the liquid food.
|Piercing-sucking||Used to penetrate solid tissue and then suck up liquid food||Cicadas, aphids, sucking lice, stable flies, mosquitoes|
|Sponging||Used to sponge and suck liquids||House fly, blow fly|
|Chewing||Used for biting and grinding solid foods||Dragonflies, termites, beetles, ants, cockroaches, grasshoppers, crickets, caterpillars|
|Siphoning||Used to suck liquids||Bees|
- Some insects, such as aphids, have piercing-sucking mouthparts. Other insects, like grasshoppers, have chewing mouthparts.
- Insects can have specialized mouthparts, such as a proboscis, to siphon the nectar from a flower.
Use the resources below to answer the questions that follow.
Explore More I
- Bug Mouthparts at Museum Victoria: museumvictoria.com.au/bugs/foodchains/mouthparts.aspx.
- Describe a honeybee's mouthparts.
- Describe the process of sponging.
- How do the mouthparts of cockroaches differ from the mouthparts of butterflies?
- What do the design of insect mouthparts tell us about their lifestyles?
Explore More II
- Ants that Farm, Compost, and Weed at http://www.youtube.com/watch?v=DNN2E2bWU3A (2:23)
- What do these ants do with the plants they gather?
- What would happen to the ants' "crop" if the ants in a colony were to all die?
- What tool do the ants have to try to control "pest" fungi?
- How do butterflies obtain their food?
- What do fleas and lice eat?
- What is sponging? Explain how insects use sponging to obtain their food.
- What is meant by the piercing-sucking method of eating?