Перефразируйте предложения, используя Perfect Infinitive в значении уверенного предположения. probably — вероятно
evidently — очевидно
Probably they have solved the problem.
Probably you left your umbrella in the bus.
Probably Helen forgot to call him.
Evidently mother took my key by mistake.
Evidently they took the wrong turning.
Of course they looks ugly, but they make useful things such as collecting rubbish. But also this insects have disadvantages too and this disadvantages are really very serious! The mail problem of them it's their ability to spread infections.
In conclusion i want to add that we need to overcome problems which connected with insects, but we mustn't kill them, because insects also make a lot of usefull things for us.