Cereal rust mite larvae are feeding on timothy leaves across southeastern Pennsylvania, according to Penn State University entomologists. Mites are active only in early spring and generally aren't a problem after first cutting. But they can reduce timothy's first-cutting yield by 30-100% and turn the crop brown, which lowers its market value. So scout now, the entomologists urge. Check whole fields. Look for purple or wrapped leaves, especially in fields with a history of mite problems. Under magnification (20x), mites look like white maggots laying in troughs between leaf veins. The eggs are round and clear to white to reddish in color. Mites feed on the surface cells of the leaf between the veins. This causes the leaf to curl, as if drought-stressed. This is really obvious in April when there is plenty of moisture and little transpiration.