This insect hatched from the long arranged eggs. At beginning their whole bodies are red in colour and then turn black after not very long time. Many similar eggs found on house wall. What this insect is and what its function to ecosystem?

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Without knowing where you are that is a very hard question. I am fairly sure (cue someone telling me I'm wrong) they are nymphs of a true bug (hemipteran). They look a lot like either assassin bugs (Reduviidae) or leaf-footed bugs (Coreidae) but both are large families withthousands of species.