Answer: Unfortunately, based on your description I am not certain which insects are bothering your squash plants. Without knowing that, it is difficult to suggest a control.
Wood ashes will affect the soil pH so I would not recommend using them, and although some gardeners have good results using dishwater, it would be better to use a commercially formulated insecticidal soap per the label directions -- this is less likely to damage the foliage. You could try the insecticidal soap and see if it is effective.
However, I suspect it is squash bugs and insecticidal soap will not control those. Here is a photo. You may need to cut and paste the complete url into your browser.
Squash bugs are very difficult to control. Handpicking is somewhat effective, especially if you can catch them while still small. Otherwise, you may need to resort to using carbaryl (Sevin).
If it is not squash bugs, then I would suggest you work with your local county extension to obtain a specific identification of the pest and then once you know that, determine how to proceed.
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