A Malaise trap is a large, tent-like structure used for trapping

Insect trap

Insect traps are used to monitor or directly reduce insect populations. They typically use food, visual lures, chemical attractants and pheromones as bait and are installed so that they do not injure other animals or humans or result in residues in foods or feeds. Visual lures use light, bright...

 flying insects particularly Hymenoptera

Hymenoptera

Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...

 and Diptera

Diptera

Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...

. The trap is made of a material such as terylene netting and can be various colours. Insects fly into the tent wall and are funnelled into a collecting vessel attached to highest point. It was invented by René Malaise

René Malaise

René Edmond Malaise was a Swedish entomologist, explorer and art collector who is mostly known for his invention of the Malaise trap and his systematic collection of thousands of insects.-Early career:...

 in 1934.

Structure

There are many versions of the malaise trap, but the basic structure consists of a tent with a large opening at the bottom for insects to fly into and a tall central wall that directs the flying insects upwards to a cylinder containing a killing agent. The chemicals vary according to purpose and access. Conventionally, cyanide

Cyanide

A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....

 was used inside the jar with an absorbent material. However, due to restrictions, many people use ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

. Ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 will damage some flying insects like Lepidoptera

Lepidoptera

Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...

ns, but most people use the malaise trap primarily for Hymenoptera

Hymenoptera

Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...

ns and Dipterans

Fly

True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...

. In addition, the ethanol will keep the specimens preserved for a longer period of time. Other dry killing agents include no-pest strips (vapona

Dichlorvos

Dichlorvos or 2,2-dichlorovinyl dimethyl phosphate is a highly volatile organophosphate, widely used as a insecticide to control household pests, in public health, and protecting stored product from insects. It is effective against mushroom flies, aphids, spider mites, caterpillars, thrips, and...

) and ethyl acetate

Ethyl acetate

Ethyl acetate is the organic compound with the formula CH3COOCH2CH3. This colorless liquid has a characteristic sweet smell and is used in glues, nail polish removers, and cigarettes...

 and need to be checked more regularly.

Design details

Cylinder

When choosing a malaise trap design, it is important to consider the types of insects you want to catch. The opening to the cylinder is of key importance. Typically, the opening is around 12 millimetre, and can vary according to the size of insect you are trying to catch. If using a dry agent, a smaller hole will result in a faster death, limiting the amount of damage a newly caught insect will inflict on older, fragile specimens. In ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

, this is less of a concern. Larger holes also allow in more butterflies, moths

Moths

Moths may refer to:* Gustav Moths , German rower* The Moths!, an English indie rock band* MOTHS, members of the Memorable Order of Tin Hats...

, and dragonflies potentially.

Location

Placement of the trap is very important. The trap should be positioned to maximize the number of flying insects that pass through the opening. This is determined by the natural features of the site. One should evaluate topography, vegetation, wind, and water. For example, if there is a wide corridor in a forest such as a trail, the trap should be oriented with its opening to the corridor. Also, places where vegetation is growing high around the opening will limit the number of flying insects that enter the trap. Other ideal places may be above small streams or on edges of forests.

A well placed trap in ideal seasonal conditions can catch over 1,000 insects a day. Even in less ideal conditions, like rain, the trap is still effective.

Other uses

The malaise trap can also function as a light trap. If a lamp is placed at the end opposite of the opening, the light will attract insects into the trap. For those who want to know what insects they are catching in the day versus the night, the specimens should be collected and removed at dawn and dusk. For others, specimens should be removed from the trap at least once a week if using ethanol, or more often if using a dry killing agent.

The design of the trap catches insects that naturally fly upwards when they hit a barrier. However, some insects drop when met with a barrier. An addition of a pan with ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 at the bottom of the main wall will catch specimens like beetles that fall before reaching the top. A trap without the netting on top but with just a preservative-filled basin under the barrier is commonly named a Flight Interception Trap

Flight Interception Trap

The Flight Interception Trap or FIT is a widely used trapping system for flying insects. It is especially well-suited for collecting beetles, since these animals usually drop themselves after flying into an object, rather than flying upward...

or FIT.