Help for my bush
This is a crape myrtle. The white film on the leaves is a fungal disease known as powdery mildew. It is hammering plants this year, because it has had ideal weather for growing conditions favoring it. Here is more: https://extension.umd.edu/hgic/topics/powdery-mildew-trees-and-shrubs
Since you have not had a problem with this disease before this year, there is a good chance that your crape myrtle has good disease resistance to powdery mildew, and it will rarely get the disease.
The insects you see are aphids.The crapemyrtle aphid produces multiple generations throughout the season so populations can increase quickly. Look for distortion and curling on new growth. Control: Check for predators and parasitoids such as syrphid flies, lady bird beetles, and wasps (look for the aphid mummies) because they do a lot to keep aphid populations down. If aphid populations are high enough to warrant treatment, consider horticultural oil. (Read the label very carefully before spraying. If temperatures are too hot, it will burn the leaves.)
Here is more about aphids: https://extension.umd.edu/hgic/aphids-trees-and-shrubs