Edible oil droplets trap bugs without the harm to people and wildlife that synthetic pesticides can cause
The insect glue, produced from edible oils, was inspired by plants such as sundews that use the strategy to capture their prey. A key advantage of physical pesticides over toxic pesticides is that pests are highly unlikely to evolve resistance, as this would require them to develop much larger and stronger bodies, while bigger beneficial insects, like bees, are not trapped by the drops.
The drops were tested on the western flower thrip, which are known to attack more than 500 species of vegetable, fruit and ornamental crops. More than 60% of the thrips were captured within the two days of the test, and the drops remained sticky for weeks.
Work on the sticky pesticide is continuing, but Dr Thomas Kodger at Wageningen University & Research, in the Netherlands, who is part of the self defence project doing the work, said: “We hope it will have not nearly as disastrous side-effects on the local environment or on accidental poisonings of humans. And the alternatives are much worse, which are potential starvation due to crop loss or the overuse of chemical pesticides, which are a known hazard.”
A key advantage of physical pesticides over toxic pesticides is that pests are highly unlikely to evolve resistance, as this would require them to develop much larger and stronger bodies.
Insect body size is dictated by oxygen levels, and since they absorb oxygen through their skin if they get too large with too little oxygen they suffocate.
You are thinking of sea scorpions who for one werent scorpions and for two were aquatic in nature only going onto the pre carboniferous land as a shortcut since there was nothing on land.
Natural selection is usually implied. So, in long form, smaller insects would have to be less reproductively successful, and that's hard when you're a pest that really benefits from being tiny, stealthy and energy-economical.