User:Scarabaeoid/bottle trap

The term bottle trap is used for some different objects. Among these are a piece of material used in bathroom plumbing, as well as various trap models made out of discarde bottles which are used to trap animals as different as beetles, mice, fish and octopusses. This article is about the use of modified bottles for trapping flying insects.

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A bottle trap is a type of baited arboreal (placed in a tree) trap widely used for collecting either prized or harmfull fruit eating beetles, especially flower beetles., leaf chafers and longhorn beetles as well as wasps and other unwanted flying insects.

Structure

A bottle trap is an insect trap made out of a plastic bottle. Most collectors use bottles of 1,5 or 2 liters to make these traps but smaller bottles may work as well. There are basically two types:

• The first one is the funnel type. These bottle traps are made by cutting off the neck of the bottle as well as the complete tapering part of the top. The neck and cap are discarded. For catching wasps it is sufficient to remove the cap while leaving the neck in place. The tapering part is placed upside down on top of the rest of the bottle, thereby effectively forming a funnel. This funnel is then fixed to the bottle by piercing both bottle and funnel at two opposing sides. A wire fitted through these holes ensures the funnel solidly fits on the bottle, while the trap can easily be opened when required. After putting the bait in the bottle the trap is ready for use.
  • Pro's:
    • Insects can't escape from this type of trap, since they fly up along the side of the bottle, not finding the exit which is in the middle
    • Bats and large moths can't enter the trap since they are to large to fit through the funnel
    • This type can, unlike the other one, also be used for collecting hindersome wasps
  • Con's:
    • Not only insects but also rain will funnel into the trap. This trap should therefore only be used in dry seasons
    • This construction requires a bit more work than the side door type
• The other one is the side door type. A side door bottle trap consists of a bottle with cap of which the higher end of one upright side is cut open. A simple rectangular shape is cut out, taking care that it stays attached to the bottle on it's upside. This plastic flap is then bend upward, effectively forming a rainshield over the entrance. After adding some bait the trap can be placed.
  • Pro's:
    • Because of it's opening with rainshield very little rain enters the trap, making it effective in wet seasons too
    • Construction is very simple and requires no additional materials
  • Con's:
    • The wider opening allows for bats and large moths to enter. These may die in the trap and pollute it, as wel as forming, with their wings, some bridge to the exit
    • Captured beetles may escape again since they may simply fly upward along the side of the bottle to escape

Bait

Many different types of bait can be used. Since this kind of trap is mainly used for beetles which are attracted to (over)ripe fruits, a bait with a certain amount of alcohol is usually very effective. Types of bait which are commonly used are:

• For beetles:
  • Banana with beer (and suger if pleased)
  • Banana with rum
  • A mixture of (cheap) red wine, vinegar and sugar
• For wasps (funnel type bottle trap only):
  • Sirup, soft drink or sugar water

Other fruits may be used as well, but banana is widely available, normally inexpensive and contains suffient sugar to start a fermenting proces by itself. The different ingredients are usually kept apart and mixed in the trap itself, but some collectors prefer to mix their bait before going into the field.

Placement

Bottle traps (like all traps) are best place where most of the desired insects are to be expected. For beetles, in general this means high up in trees, preferably flowering or fruiting trees. However, very good results can also be obtained from forest borders. Traps placed inside forests usually yield smaller amounts of beetles, but also different species. Traps for luring wasps are best placed on a short distance (several meters) from the place where they are hindersome. Placing traps can be done in various ways:

• by making a small hole in them (and subsequently bending down some branch and fitting it's top through the hole)
• by attaching a thin cord on them (after which the cord can be thrown over a high branch and the trap pulled up, the rope then being fixed to some lower branch)
• fixing some wire hook on them (and then either manually or with the aid of a long stick hanging them over a branch)
• by just placing them on the ground

The first three methodes are used most often for collecting beetles, while the latter two are more commonly used for catching wasps.

Bycatch

Next to the desired beetles, many other insects may find the bait attractive. Sap beetles (a group of small fruit-eating beeetles), moths like the large white witch moth, various butterflies, cockroaches, flies, stingless bees, wasps and even small fruit eating bats may enter the bottle traps as bycatch while aiming for beetles. Such unwanted animals may cause several problems:

• They pollute the trap. Because they cannot escape the trap, they will, like the beetles, eventually die in it. Especially fragile insects like moths and butterflies will live only for a short time in these traps. After they die, their bodies will quickly start rotting, and their intestines as well as the scales on their wings will pollute the bait. Although this will not necessarily alter the attractiveness of the bait to other insects, the remains of unwanted specimen will make it more difficult to check the bait for desired beetles
• They may create an escape route for trapped beetles. Especially the very long wings of the neotropical white witch moth may form an effective bridge from the bait to the opening of the trap
• Protected species such as bats may enter the trap not being able to leave it again

See also

• Entomology
• Insect collecting
• Pitfall trap
• Malaise trap
• Flight Interception Trap (FIT)