May one check produce for infestation―on Shabbat and holidays? Must we fear that such checking comes under the category of borrer, orselecting, and is prohibited on Shabbat?
Answer: As long as the insect is relatively large and easily distinguishable―it may be removed28.
This is comparable to removing a feather from a garment. It is permitted, since the feather is distinguishable from the garment and stands apart from it. The case of a relatively large insect is the same.
As a precaution, however, one should take some of the food substance away together with the insect. This would not be considered as removing bad, which is prohibited, but, rather, as removing good and bad from good–which is permitted29.
If, on the other hand, the insect is relatively small and difficult to distinguish from the food substance, one may not remove it, as is, on Shabbat. One may, however, remove some of the food together with the insect. In such a case, one is not removing bad from good. One is removing good and bad from good―which is permitted.
One may not soak foods on Shabbat and holidays in order to remove the insects that are upon them30. This is indeed borrer (separating), and is prohibited. (In addition, if the insects are alive and the soaking kills them, a second prohibited action—killing the insect—has taken place.) 31