Effective Techniques for Insect Trapping Using Natural Baits
In entomology and pest management, effective trapping methods are essential for studying insect behavior, monitoring populations, and implementing control strategies. Among the various techniques employed, those utilizing natural baits have proven particularly effective. From rotting meats and fermented liquids to colorful visual cues, these baits attract a diverse range of insects.
This article explores some trapping methods.
Chromotropic traps
Chromotropic traps are simple traps that use colors to attract insects. Typically, small bowls or colored ice cream containers (3 coats of spray paint give excellent results) are used, filled almost to the brim with water and soap. The soap reduces the surface tension of the water so even the most agile insects cannot escape the trap.
Colors vary depending on the insect you want to attract:
- Yellow: primarily attracts Jewel beetles (Anthaxia and Acmaeodera especially), Longhorn beetles (only flower beetles), Tumbling flower beetles, Diptera, various Hymenoptera (Chrysididae, Apoidea, Pompilidae, Sphex, and Ichneumonidae).
- Red or pink: used particularly for Rose chafers (Cetoniinae), but also attracts some other beetles and few Hymenoptera.
- There are also other chromotropic traps mainly used in phytopathology and triggered differently (e.g., blue traps against Thrips).
It is recommended to leave them in action for a couple of days and then check them, removing the catch insects and adding water and soap if necessary.
Sweet hanging traps
Sweet hanging traps are classic plastic bottles filled halfway with wine and salt or beer and salt. Fermenting wine or beer attracts many insects, including Flower chafers (Protaetia cuprea, Cetonia aurata, Netocia morio ...), Hymenoptera (9 out of 10 are usually Vespa crabro), Longhorn beetles, Moths, Diptera, and occasionally a Jewel beetle that accidentally falls while flying among the foliage. Salt serves as a preservative.
To build them, you can proceed in two ways:
- Cut off the upper part of the bottle (from the narrow part upwards);
- Make two windows in the upper part of the bottle.
The first method is more useful for catching dead insects to put in an entomological box, the second for catching live insects. In the latter case, care must be taken to put something that prevents the insects from drowning, such as a piece of polystyrene or a glued net.
Vinegar drop trap
This is the simplest trap. Just take a container 15-20 cm tall (the best are half-liter yogurt cups) and fill it halfway with vinegar and salt. Then bury it up to the brim in strategic points like at the base of trees or under rocks. It is also important to remember to put some kind of shield to prevent it from filling with leaves or debris, for example, by creating a network of branches around the opening.
It primarily attracts Ground beetles, but other insects may also fall into it.
Traps with excrement
As the name suggests, these are traps filled with various types of excrement. The best are equine, caprine, and bovine (although bovine has collection issues due to its consistency); in African countries, elephant dung is used. They are made like vinegar traps, filling a jar or bucket with excrement and burying it up to the brim. They should be placed in open areas (such as pastures and clearings) frequented less by people.
They obviously attract coprophagous insects like Dung beetles (Afodiinae and Geotrupini) and many Diptera.
Trap with meat
These are traps that use decaying meat as bait. The best types of meat are those that decay quickly, such as liver, other offal, or pieces of fish; even better, carcasses of small mammals or birds in various stages of decomposition are preferred.
The construction consists of two containers, one inside the other: take a plastic bottle with a window in the upper part and hang another smaller container inside it (baby food jars work well) with many holes. Water and soap are placed on the bottom of the bottle, and the bait is placed in the smaller container. This method prevents insects from getting dirty with the bait and allows for more hygienic collection.
You can decide whether to place it on the ground or hang it from a tree depending on what you want to collect:
- On the ground, it is much more productive and allows for the collection of Rove beetles (Staphylinidae), Carrion beetles (Silphidae, especially Silpha and Thanatophilus), Hide beetles (Trogini), and other necrophagous insects and Diptera.
- Hanging from a tree attracts fewer insects but interesting ones; it allows for the collection of Sexton beetles (Nicrophorus), which are more common in hanging traps than in ground traps. Additionally, Rove beetles (Staphylinidae) and Diptera are also attracted.
There are also mentions of hanging traps with 95% alcohol placed in coniferous forests, but I have never personally tried this due to doubts about its effectiveness and the high cost of alcohol. It is said that alcohol emits odors identical to those of conifer resins, thus attracting wood-boring beetles associated with them. However, as mentioned earlier, this remains uncertain.
