What's eating my cosmos?

Cosmos are relatively pest-resistant, but aphids cluster on new growth and spreading stems. Thrips streak petals, and spotted cucumber beetles feed on flowers in North American gardens. Caterpillars and earwigs cause occasional leaf and petal damage. Deer and rabbits browse cosmos readily in rural gardens. Their drought tolerance and fast growth mean healthy plants usually outpace most minor pest pressure.

Clusters on stem tips and buds; sticky honeydew and distorted new growth; populations build quickly in summer. Blast off with water; apply insecticidal soap or neem oil. Attract beneficial insects by growing companions such as sweet alyssum nearby.

White to silver streaking and flecking on petals and leaf surfaces; petals may brown and fail to open fully. Remove and discard affected blooms; spray with spinosad or insecticidal soap targeting buds and leaf undersides. Use blue sticky traps to monitor.

Adults feed on open flowers and soft petals, leaving chewed ragged holes; primarily a problem in the US Midwest and South. Hand-pick beetles from flowers; apply kaolin clay as a deterrent. Pyrethrin sprays are effective for heavy infestations.

Young plants browsed to stubs; mature plants have stems and flowers cleanly nipped off at browse height. Surround beds with wire mesh fencing (at least 2 ft high for rabbits, 6 ft for deer). Repellent sprays with repeated application provide some protection.