What pests affect daylilies?
Daylilies do have some pests, but many do only minor damage.

Aphids
Daylilies have their own specific aphid which feeds only on daylilies.

Aphids are most active in cool weather spring and fall in temperate zones, and all winter long in the subtropics.

Controlling daylily aphids is not as easy as with other kinds of aphids, which are usually vulnerable to such soft controls as soaps.

In order to reach daylily aphids inside the fans, a pesticide with at least a mildly systemic action is needed.

Do not use the pesticide Kelthane, which is known to harm daylilies.

Spider Mites
Spider mites are among the most common daylily pests.

Spider mites are most active in hot, dry weather.

You can get some control of spider mites just by hosing them off as needed.

Again, do not use the pesticide Kelthane; it is known to harm daylilies.

Thrips
Several species of thrips are know to infest daylilies.

Control thrips by starting early in the growing season with a pesticide having either a systemic or long residual action.

To repeat, do not use the pesticide Kelthane.

Slugs and Snails
Slugs and snails feed on the young, tender tissues, causing ragged edges and holes.

They feed at night and hide during the day in cool, moist places, such as in mulch, under rocks and bricks, and in dead foliage.

Sanitation helps to control slugs and snails. Otherwise, control requires using pesticides which are targeted specifically at these pests.

Other Pests
There are other pests that attack daylilies.

Other insect pests which have been reported affecting daylilies include cutworms, tarnished plant bugs, cucumber beetles, wasps, Japanese beetles, grasshoppers, and periodical cicadas.

Bulb mites may be involved in the transmittal of crown rot.

Deer will sometimes eat daylily flower buds.