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The Effects of Insecticide on Ladybugs

Researched by Jennifer M. 



The purpose of this experiment was to determine the effect of insecticide on ladybugs.

I became interested in this idea because I know that ladybugs are beneficial insects.  They live around insect pests, which leads to accidental spraying of the ladybugs.  Farmers need the ladybugs to help keep down pest population, and need to avoid killing them accidentally.

The information gained from this experiment can warn farmers to be extra-careful when using insecticide.



My hypothesis  is that the organic  insecticide  will kill the ladybugs  faster than  Sevin.

I base my hypothesis  on the fact that my parents  and I have used soap and water to kill potato bugs, and that  is like an insecticide.  The natural  insecticides  usually  work better.



The constants in this study were: the same amount of insecticide, the same type of ladybug, and the same size of ladybug.

The manipulated variable was: the type of insecticide.

The responding variable  was: the percentage of the ladybugs that die from each  insecticide.

To measure the responding variable I will observe the ladybugs after spraying them with insecticide, counting how many die.



Marking pens to label boxes
Sheets of plastic
Pencil to poke holes in boxes
Pair of yellow kitchen gloves
Gallon container of distilled water
Types of insecticide
Roll of scotch tape




1. Purchase 2 different types of insecticide, and 1 gallon of distilled water. 
2. Purchase about 100 ladybugs. 
3. Gather 3 shoeboxes. 
4. Divide each shoebox into 3 different compartments with slats of cardboard and tape. 
5. Poke air holes in sides of all the shoebox compartments. 
6.With a marking pen, label each shoebox: " Sevin", " Organic", and " Control." 
7. Clean sprayer. 
8. Fill sprayer with Sevin insecticide, mixed according to instructions on container. 
9. Place about 5 ladybugs inside the first compartment in the " Sevin" box. 
10. Uncover the shoebox. 
11. Spray this group with Sevin insecticide. 
12. Record time. 
13. Observe ladybugs for a few seconds. 
14. Repeat steps 9-13, 2 more times for this test substance. 
15. Repeat steps 9-13 3 times with organic insecticide. 
16. Repeat steps 9- 13 3 times with distilled water (as a control.) 

The original purpose of this experiment was to determine which insecticide worked best, Sevin, or the Organic. 

The results of the experiment were Sevin killed nearly all of the ladybugs, while the Organic destroyed only about 3.  Therefore Sevin worked much faster than the Organic.  Most natural remedies for killing bugs don’t work nearly as well as I thought at first. 

My hypothesis was that the organic insecticide would kill beetles  more effectively. 

The results indicate that this hypothesis is incorrect.  Sevin worked best by far. 

Because of the results of this experiment, I wonder if farmers would see that although Sevin is not a very strong insecticide, it works well, ( at least on ladybugs.)  I could use this information to show farmers that when spraying, be very careful to spray the insects you are aiming for, and not the ladybugs, too.  Ladybugs are not hard to kill, especially if you are using Sevin. 

If I were to conduct this project again I would start gathering up my supplies sooner, reconsider my hypothesis, and use more ladybugs in each test group.  On this experiment I only used 5 ladybugs for each trial which is too few for a valid test.




Ladybugs  are beneficial  insects.  They are helpful to people, eating aphids, and helping to save many  crops.  When  people spray plants to rid them of harmful insects, they are also killing the ladybugs.  It doesn’t take  a very strong insecticide to kill the ladybugs.  Farmers, and anyone else, who sprays their gardens, need to watch for ladybugs and other beneficial insects.      


Insecticide  is very harmful to insects, humans, or even animals that get hold of it by accident.  Insecticide  is a poison.  It was created to kill insects.   
There are many  different types of insecticide.  One type was DDT.  DDT was an insecticide  introduced in the 1940’s to battle  a variety of insects.  Insects stored the DDT in their fatty tissue.  DDT  was banned from the United States in 1972, due to damage to the environment. 
Other  insecticides, called stomach poisons, kill insects when eaten. 
Systemic insecticides  are sprayed or injected, into plants and even animals. 
Contact  poisons kill insects when touched. 
Organic  insecticides  are natural  insecticides.  They  consist of carbon, hydrogen and oxygen atoms.  Three main types of organic  insecticides are chlorinated hydrocarbon, organic phosphate, and carbamate insecticides.  Organic  insecticides are usually most often used.  
Organic  phosphate  insecticides  are very poisonous to humans, but don’t leave harmful chemicals  in food. 
Parathion, an insecticide, provides excellent  protection against  plant lice. 
Botanical  insecticides are  insecticides  made  from plants.  Rotenone is a poisonous substance  discovered in derris and cube  plants.  It can be used to kill fish that are not wanted when cleaning lakes  out. 
Inorganic  insecticides are quickly being replaced to reduce  danger of contamination.  They are mostly made  from minerals. 
Microbial  insecticides  infect  insects with diseases. 
Soybean oil is used to kill insects.  It will not burn plants in cold weather. 
Mosquito dunks are another  product that  kills mosquito larvae  in still water. 
Carbamate  insecticides  don’t leave harmful chemicals  in food, but some can harm warm-blooded animals. 
Nicotine  makes a strong insecticide  against  aphids. 
As you can see, there are many different  kinds of insecticide.


Ladybugs  help us keep down pest population.  Since they are around  insect  pests all the time, they are often sprayed by accident. 
A ladybug’s  maximum  length  is .5 in. Ladybugs have had their name since the Middle Ages.  Ladybugs  were looked  at as a gift from the Virgin Mary because of their eating habits.   
Even when they are only larvae, ladybugs  eat  aphids  and other pests. 
In the late 19th century, California farmers released  ladybugs  on their crops in order to save the plants from destruction by the cottony-cushion scale insect. 
Ladybugs  are often red or orange.  They  are usually spotted with black, white, or yellow. 
Adult  two-spotted  ladybugs  often hibernate  in houses during the winter season.  Ladybugs  hibernate  together  in sheltered  places, piled in huge masses.  
Ladybugs  are very helpful, and shouldn’t  be getting  sprayed by farmers, even if it is by accident. 


Insecticide is very harmful to insects, humans, or even animals that get hold of it by accident.  
Insecticide is a poison.  Ladybugs help us keep down pest population.  Since they are around insect pests all the time, they are often sprayed by accident.  Farmers need to make sure they do not spray ladybugs, that they spray the harmful pests. 

Coble, Harold.  “ Insecticide,” World Book Encyclopedia,  1995. 
Doris, Ellen.  Insects.  Danbury, Connecticut:  Grolier Educational, 1996. pp.60-61 
“ Insect,”  WorldBook Encyclopedia, 1991. 
“ Ladybird Beetle,”  Encarta, 1998. 
“ The Natural Gardening Company.”  [ Online] Available http://

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