Onions may from time to time be infested with thrips. This is especially true in Spanish onions. Therefore, you should peel outer layers and discard. Then, rub in hands while washing under water. After, examine outer layer for presence of insects
The Vaad does not recommend checking this item because some national hashgochas do not recommend it. However, for one who still want to use fresh broccoli, the Vaad recommends using the STEMS only. You should wash the stems thoroughly with water. No inspection is necessary
The topic of flour as it relates to the requirement of sifting is a subject with various opinions. During the warmer months (May – October), is measurably more prone to insects than during the rest of the year. Generally during the winter months, flour, both because of the outside weather conditions and inside storage conditions, is less prone to insect presence. Nevertheless, it is a good practice to take three cups of flour, pour them onto a white surface (e.g., a paper plate or parchment paper), and with your fingers spread out the particles of flour while looking for small insects or worms. This practice, at minimum, should certainly be done during the summer months as well. If insects are found, the entire bag should be checked. If three insects are found in the bag, discard the entire bag.