Insect Food

Insect Food
Jessica Harwood
Douglas Wilkin, Ph.D.
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AUTHORS
Jessica Harwood
Douglas Wilkin, Ph.D.
EDITOR
Douglas Wilkin, Ph.D.
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Printed: March 12, 2015
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Doris Kraus, Ph.D.
Niamh Gray-Wilson
Jean Brainard, Ph.D.
Sarah Johnson
Jane Willan
Corliss Karasov
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C HAPTER
Chapter 1. Insect Food
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Insect Food
• Distinguish methods of insect eating.
• Define proboscis.
• Explain sponging.
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.
Insect Food
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
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predators, hunting other small creatures. Insects like mosquitoes and aphids have special mouthparts that help them
pierce and suck. Others, like assassin bugs ( Figure 1.1) 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.
FIGURE 1.1
An assassin bug feasts on a beetle.
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 1.2).
FIGURE 1.2
Caterpillar feeding on a host plant.
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.
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Chapter 1. Insect Food
TABLE 1.1: How Insects Eat
Method
Piercing-sucking
Sponging
Chewing
Siphoning
Description
Used to penetrate solid tissue and
then suck up liquid food
Used to sponge and suck liquids
Used for biting and grinding solid
foods
Used to suck liquids
Examples
Cicadas, aphids, sucking lice, stable
flies, mosquitoes
House fly, blow fly
Dragonflies, termites, beetles, ants,
cockroaches, grasshoppers, crickets, caterpillars
Bees
Summary
• 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.
Explore More
Use the resources below to answer the questions that follow.
Explore More I
• Bug Mouthparts at Museum Victoria: http://museumvictoria.com.au/bugs/foodchains/mouthparts.aspx .
1.
2.
3.
4.
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)
1. What do these ants do with the plants they gather?
2. What would happen to the ants’ "crop" if the ants in a colony were to all die?
3. What tool do the ants have to try to control "pest" fungi?
Review
1.
2.
3.
4.
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?
References
1. Audrey (Flickr:audreyjm529). An assassin bug feasts on a beetle . CC BY 2.0
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2. Jo Naylor. Caterpillar feeding on a host plant . CC BY 2.0
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