For the second year in a row, my monarda plants have been eaten before bloom...

Asked June 18, 2014, 11:17 PM EDT

For the second year in a row, my monarda plants have been eaten before bloom time. Today I was able to see several small yellow bugs about a quarter of an inch long, and also gooey black spots which I presume to be eggs all over the plants. The plants looked healthy just a few days ago. The bugs look nothing like the pictures on your web page, although I understand they could be in a different stage of development. Can you help me? Other info: our soil is very sandy, although we have had loads of rain this year. Nearby plants include peonies, johnny jump-ups, cat mint and day lilies. Nothing else has any issues.

Stearns County Minnesota

5 Responses

The fourlined plant bug, Poecilocapus lineatus, is causing the severe damage. Young nymphs are red-orange with black markings on the thorax. Adults are yellow or greenish yellow oval-shaped body with four distinct black stripes on the wings. Four-lined plant bug feeding results in round, depressed spots on leaves. Pitted areas eventually turn black or translucent. These spots may coalesce, forming large blotches. Most of the damage is usually caused by the nymph stage. By the time adults appear much of the damage has been done. Soaps and oils are effective on the wingless nymphs. Sevin, malathion, and some of the newer pyrethroids, such as cyfluthrin and permethrin work on both stages. Cut down host plants in the fall to remove eggs that may have been inserted into them. Be sure to bury or compost removed plant material or remove residues from the landscape area.

This does not match my bugs at all. See pictures.

Here is an additional picture.

The insects in the photo are larvae of a kind of leaf beetle (Cassadine). They might be the one spotted tortoise beetle (Physonota unipunctata). The black stuff is excrement.

See below for more information:

An Offensive Chemical Defense

One Spotted Tortoise Beetle

That looks like what I have. Thank you!