Background for Teachers

We’ve introduced this month’s “Bloodsuckers” topic with a short story you can use as a read-aloud or as independent reading.

However you decide to use it, make sure students come away knowing that:

  1. only female mosquitoes eat blood. 
  2. female mosquitoes need the fats and proteins in blood to help develop their eggs.
  3. female mosquitoes eat a blood meal just before it is time to reproduce.
  4. as annoying as we may find mosquitoes, many other animals in Texas depend on them for their own survival.
  5. when female mosquitoes do not need to eat blood they eat nectar, which is what males always eat.
  6. female mosquitoes do not bite, they poke, using a proboscis much like a straw.
  7. while the females suck blood through one part of the proboscis they send an anti-coagulant through another part of it to keep blood from thickening.
  8. You can add to the discussion that female horseflies and deerflies also need a blood meal before they can lay their eggs. They too, like the males of their species, eat nectar when they don’t need to eat blood.

Why Do Bloodsuckers Suck Blood?

Bloodsuckers don’t suck blood to be mean. When they take blood out of an animal it is because they need the blood to survive.  As you help your students understand this, you can make the analogy of how we don’t eat hamburgers to be mean to cows or chow down on chicken nuggets to be mean to chickens.  Rather, we eat meat (which has residual blood in it) because we need the protein it provides.

The proteins found in blood (and meat) contain amino acids. Amino acids are considered the building blocks of all living things. We could not survive without them, nor could any other animal.

How Do Bloodsuckers Get the Blood Out?

Bloodsuckers use different kinds of mouthparts to get blood out of hosts. (An exception are leaches which have no mouthparts.)

Check out these two groups of bloodsuckers based on two major types of mouthparts:

Poke and Suck Mouthparts

Some poke with a needle-like proboscis then use it as a straw to suck blood.

KISSING BUG Kissing Bug - Tx Dept State Health Services

Kissing bugs get their name because they often bite near the lips.  When animals sleep they exhale carbon dioxide and that attracts kissing bugs to the host’s mouth.

Kissing bugs are also called “Assassin bugs” because they “assassinate” (kill) other bugs. But that’s good news for us because the bugs they kill and eat are often pests that damage our crops. Too bad kissing bugs/assassin bugs only need to eat about once every three weeks!

Where do they live?
They often live where crops are grown or near houses.

We tend to find kissing bugs more often in south Texas.

Lone Star Tick male - Tx Dept State Health ServicesTICKS

Lone Star Tick female - Tx Dept State Health Services

Ticks don’t have true heads, just barbed mouthparts that they stick into the host. Ticks create a cement-like substance to glue themselves on and can’t leave until they fill up, even if they want to!  

In Texas, there are two types of ticks: hard ticks and soft ticks.  You are probably more apt to see a hard tick since soft ticks live in burrows and places where birds reside. Some types of ticks can live up to 200 days without food or water! And some kinds of ticks can live up to two years!

Check out this cool site to learn more about ticks:  PestWorldforKids.org

There are four kinds of hard ticks in Texas. One of them, the Lone Star Tick is the vector of Lyme Disease. That means it carries this disease.  A vector carries a disease, but does not actually have the disease itself.

Tick-borne diseases in Texas are on the rise and you should be aware of the signs of these diseases.  TickTexas has some great information on the topic: http://www.ticktexas.org/diseases/index_diseases.htm.

Please take the time to teach your students these important tick safety tips:

·         Before you head out to the woods, brush, or grassy areas where ticks live, ask an adult to help you put on bug repellent with DEET in it.

·         Stop often to check for ticks. Wearing light colors makes them easier to spot.

·         Check your pets for ticks, especially during hot weather.

·         If a tick has attached itself to you, tell an adult as soon as you notice. Don’t squish it or try to remove it yourself! There’s a special way to remove ticks and you don’t want goo from its guts to get on you.

·         If you get a rash that looks like a bull’s eye or feel like you’ve got the flu, tell an adult. 

But...PLEASE...!!
Be careful about the way you discuss this topic with children as it would be a shame to needlessly scare them from enjoying the outdoors.  While tick-transmitted diseases can lead to serious health issues, the risk of this happening decreases significantly when children (and adults) correctly follow safety steps when in tick environments.

Where do they live?

Soft ticks live in nests, burrows, and caves

Hard ticks live in bushes and on mammals such as deer.

Asian Tiger Mosquito - Tx Dept State Health ServicesMOSQUITOES

Next time a mosquito makes you itch, you can say “Ouch, she poked me!” because, like many other bloodsuckers, the females need a blood meal before they can lay their eggs. The rest of the time they suck up plant juices with the males. Males only live about a week, while the ladies last 4-8 weeks.  

Check out this really cool photograph of the tip of a female proboscis by artist/photographer Dennis Kunkel: http://www.astrographics.com/GalleryPrintsIndex/GP2108.html. Amazing, isn’t it?  Mr. Kunkel had to use a very special lens to take that photograph.

This video is quite interesting and the kids will enjoy it.  It is also extremely short: http://video.kids.nationalgeographic.com/video/player/kids/animals-pets-kids/bugs-kids/mosquito-kids.html

Where do they live?

Mosquitoes live in water until they are adults. That’s why as a way to decrease exploding mosquito populations, in one of this month’s EXTENSIONS’ activities we suggest that students make a habit out of eliminating sources of standing water in their yards. Check out this article: http://www.portlavacawave.com/articles/2010/05/10/news/doc4be4ac50500f9812660602.txt

Cat Flea - Tx Dept State Health ServicesFLEAS

The most common flea in Texas is the cat flea, but they’ll gladly suck the blood of dogs and people, too. Fleas are such expert jumpers that they can leap from one end of a cat’s tail to the other!

Their specially shaped flat bodies allow them to move easily through the hair of their hosts. Adult fleas eat blood, but the babies’ first meal is their parents’ poop. Yum, yum! NOT!

Where do they live?

Baby fleas live on cats, dogs, and deer until they are able to jump off.  Adult fleas live in the grass or in carpet where they wait until they are hungry again. When they are hungry again and a host comes near, the adults will jump onto the host and eat until they are full. When they are full, they will jump off again and chill out for awhile.

Bed Bug - H.J. Harlan, AFPMBBED BUGS

Ever heard the saying, “Sleep tight and don’t let the bed bugs bite?” That’s because bed bugs only come out at night while we’re sleeping.

It takes a bed bug about 10 minutes to fill up (become engorged) and it won’t need to eat again for several days.  In fact, adults can survive for up to a year without blood!

Females lay 3 or 4 sticky eggs every single day near where humans sleep, since our blood is their favorite feast.

It used to be that it was unusual to find bed bugs in the United States. However, today it is becoming a problem. Health authorities aren’t sure of exactly why, but one theory is that the last decade has seen a significant rise in the amount of international travel. As a consequence, hotel rooms, suitcases, clothing, etc. human beings perpetually move about from bed-bug infested areas to non-infested areas faster and more frequently than ever before, spreading the critters about the world as never before as we do. 

Check out this video about them. You may want to preview it first in case you have children in your classroom with imaginations that may keep then from sleeping tonight: http://video.nationalgeographic.com/video/player/animals/bugs-animals/other-bugs/bedbugs.html

Where do they live?

Bed bugs live in tiny cracks in walls and under carpets, and under mattress seams.

Slash and Lap Mouthparts
Some make a slash with a sharp mouthpart and lap up the blood, like a sponge soaks up water.

HORSEFLIES: See photo at http://insects.tamu.edu/images/insects/common/images/cd-43-c-txt/cimg224.html>

Horseflies look like huge supercharged flies. You can guess where they get their name....but, hold those reins...horseflies actually dine on cattle more than horses. And brown and black cows beware! Moving and dark objects make favorite targets. Only females about to lay eggs eat blood otherwise they dine on nectar with the guys.

 

Where do they live?
 Horseflies like to live around farms and horse stalls and places where we keep cattle.

 

DEER FLIES:

Deer Fly - John Moore, AFPMBDeer Fly - AFPMB

Only female deer flies chomp on hosts and only when the time comes to lay eggs – up to 1000 at one time! Otherwise, these girls eat nectar just like the boys. They get their name from their favorite host: deer.

Check out this photo and learn a little bit more about deer flies: http://kids.yahoo.com/animals/insects/3781--Deer+Flies

Where do they live?
Deer flies prefer to live near plants, especially those that produce flowers.

LICE

The word “lice” is a plural word.  Do you remember what “plural” means? It means “more than one.” So, “lice” refers to more than one bug. The word “lice” refers to two or more of these kinds of bloodsuckers. A “louse” is just one of this kind of bloodsucker.

Head Louse - Tx Dept State Health ServicesEach tiny louse is about as big as the period in this sentence. That makes them tough to find.  Some types of lice live only on humans (in our hair), while others live on different animals. That’s why you can’t get lice from your dog or cat. A louse cannot hop or fly from one host to another. To move they must crawl.
 

The kinds of lice that live in our hair are called head lice. They feed on human blood and will die within 24 hours (that’s 1 day) if they fall off your scalp.  But, chances are they won’t fall off and if you get them you will need a special shampoo and comb to get them off.  That’s why it is not a good idea to share brushes or combs with other people. 

Each louse lays 8-10 eggs per day!  An egg is called a “nit.”  These nits make your scalp itch a lot!

Check out this silly and fun website and learn more about lice:  http://www.headlice.org/kids/animations/index.htm

Where do they live?

The head lice that eat human blood live in our scalp...that’s our head, where our hair grows. Since they actually live on another animal (in this case, us!) we call them parasites. 

No Mouthparts

LEECHES

Leeches are really different from other bloodsuckers because they don’t really use mouths to get blood from hosts. They use super strong suckers to attach themselves to a host and suck on its skin until some blood comes through.

As painful as that sounds, leeches actually don’t really harm skin and you can easily pull them off.   Not all leeches in Texas suck blood, but those that do like fish and turtle blood best.

Where do they live?
Leeches live in water and look like slugs. 

How Do Bloodsuckers Find Hosts?

Most bloodsuckers have special carbon dioxide detectors that help them find hosts. Carbon dioxide is what animals exhale. So when a bloodsucker detects carbon dioxide in the air it knows that an animal with blood is nearby.

Ever notice how one minute there are no mosquitoes and the next minute it seems like there are millions of them all over you!!!!?? That’s because some types of mosquitoes can detect carbon dioxide from up to 200 feet away!

Why Do Bloodsucker Bites Sometimes Itch?

When bloodsuckers eat blood, they leave some of their spit (officially called saliva) behind. When you itch, it is because your body is having a small allergic reaction to bloodsucker’s saliva.

Do Bloodsuckers Carry Diseases?

Some bloodsuckers carry diseases. Ticks, especially should be discussed because they carry Lyme Disease and Rocky Mountain Spotted Fever.

In Texas, the Lone Star Tick is the vector of Lyme Disease. This is the most serious disease carried by the bloodsuckers you have learned about. A vector is something that carries a disease that does not actually have the disease itself. The Lone Star Tick is a hard tick.

Here is a picture of a Lone Star Tick: http://www.cdc.gov/ncidod/dvbid/stari/stari_LoneStarConcern.html

Do you notice the light colored “star” on its back? That’s how it got its name. Lone Star Ticks are very little – about as big as the lead of your pencil – so they can be hard to spot.

You can review the safety steps with the children and/or have them do this interactive activity:

Student Activity: http://www.dshs.state.tx.us/kids/lessonplans/lymedisease.shtm
Since you have already discussed tick safety tips with your class, this activity would be a great way to review what your kids have learned and allow them a chance to work in an interactive environment. The level of difficulty is about 3rd grade so this would be good for some of your special learners who would especially benefit  from a review.

IMPORTANT NOTE: If a child is ever bitten by a tick, remove the tick and put it in a jar so that it can be brought to the Texas Department of State Health Services, Infectious Disease Control Unit for testing. The Department will test it for Lyme and other tick-borne diseases. For more information contact DSHS at (512) 458-7676 or their website at: http://www.dshs.state.tx.us/idcu/disease/lyme/.


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