science

Killing jar

Killing jar is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Killing jar rather than just read about it. In short: A killing jar or killing bottle is a device used by entomologists to kill captured insects quickly and with minimum damage. The jar typically contains gypsum plaster (plaster of Paris) on the bottom to absorb a killing fluid.

Key takeaways

Killing jar belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Killing jar to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Killing jar from memory before moving on to harder problems.

Reference excerpt

A killing jar or killing bottle is a device used by entomologists to kill captured insects quickly and with minimum damage. The jar typically contains gypsum plaster (plaster of Paris) on the bottom to absorb a killing fluid. The killing fluid evaporates into the air and gasses the insect. Typically only adult hard bodied insects are killed in a killing jar; other insects require different methods of killing.

Jar set-up The jar, typically glass, must be hermetically sealable. One design has a thin layer of hardened plaster of Paris on the bottom to absorb the killing agent. The killing agent will then slowly evaporate, allowing the jar to be used many times before it needs to be refreshed. The absorbent plaster of Paris layer also helps prevent the agent sticking to and damaging insects. Crumpled paper tissue is also placed in the jar for the same reason. A second method utilises a wad of cotton or other absorbent material placed in the bottom of the jar. Liquid killing agent is added until the absorbent material is nearly saturated. A piece of stiff paper or cardboard cut to fit the inside of the jar tightly is then pressed in.

Killing fluids

The most common killing agents are ether, chloroform and ethyl acetate. Ethyl acetate has many advantages and is very widely used. Its fumes are less toxic to humans than those of the other agents, and specimens will remain limp if they are left in an ethyl acetate killing jar for several days and the ethyl acetate is not allowed to entirely evaporate from the specimens. It also preserves the body colors of some insects, such as dragonflies, that would otherwise lose their color, especially if there is a liquid layer to saturate their body tissues. A disadvantage is that, although the insects are quickly stunned by ethyl acetate, it kills them slowly and specimens may revive if removed from the killing jar too soon. Isopropyl alcohol is an easy to find and use killing agent for amateurs. Potassium cyanide or other cyanide compounds, including calcium cyanide, are also used, but only by experts due to its extreme toxicity. It also has the disadvantages that it makes the specimens brittle when left in the jar for several hours and that it may also cause some discoloration of colored specimens. It does kill rapidly, and the cyanide charge will last a long time. A few drops of acetic acid will increase the cyanide gas production. If the jar is not used for long periods it may dry out and produce little gas; a few drops of water will help get the process going again. The potassium cyanide slowly decomposes, releasing hydrogen cyanide. In former times, amateur entomologists commonly used the thick green leaves of the Cherry Laurel (Prunus laurocerasus or Prunus caroliniana) which, crushed or finely sliced, will similarly release hydrogen cyanide.

Types of insects Gassing in a killing jar is typically only used on adult hard-bodied insects. Soft-bodied and hard-bodied immature insects, such as the larval stage of many insects, are generally fixed in ethanol at 70–80% concentration in a vial. Dropping them in the vial containing ethanol both kills and preserves them. Higher concentrations of ethanol are not recommend for use with soft bodied insects, as it can distort and harden the body. Parasitic wasps are typically fixed in 95% alcohol to preserve the wing structure. Butterflies and moths are generally killed manually by crushing the thorax, as they can often destroy their wings by beating them against the jar.

See also Insect collecting Container glass

References

External links Collecting and Preserving Insects and Mites: Tools and Techniques How to Collect and Prepare Forest Insect and Disease Organisms and Plant Specimens for Identification Archived 2010-06-13 at the Wayback Machine A.Tereshkin Killing Jar with pieces of rubber tube for absorption of chloroform.

Illustrations

Worked examples

Example 1 — a first encounter with Killing jar

Start with the simplest possible case. Write down what Killing jar claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Killing jar before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Killing jar ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Killing jar

In research: Killing jar appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Killing jar in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Killing jar is common in secondary-school and first-year university syllabi. It links to neighbouring topics Animal killing, Entomology equipment, Glass jars, so understanding it makes those chapters shorter.
In everyday life: Look for Killing jar outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Killing jar in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Killing jar means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Killing jar out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Killing jar in simple terms?

Why does Killing jar matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Killing jar?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Killing jar.