Something is devouring my plants

Question: Wednesday, June 27, my flowers and herbs were fine.  Thursday morning something had eaten the leaves on various plants leaving just the stems (pictures attached).  Plants affected are thyme, spearmint, hot lips salvia, annual blue salvias, a perennial blue salvia, yellow petunia, sweet potato vine and sunflowers.  Some of my vinca leaves are also being eaten.  I cannot see anything on or around the plants.  Any thoughts?

responder: An Ask Extension Expert Replied July 02, 2024, 11:52 AM EDT
response: It is likely this is slug/snail damage to those plants. They do their damage at night hiding under rocks, boards, leaves, mulch during the day. You can identify slugs/snail by trails of shiny mucus which are left behind. Look for them under plants where it is shady or with a flashlight at night. To discourage them create lighter and drier conditions so there are fewer places to hide. For control handpick and destroy them. Set out flat boards, shingles or damp newspapers then check under those traps in the morning and repeat until they are no longer appearing. Beer traps can also be set out. If nonchemical methods don't reduce the damage from slugs/snails, there are pesticide baits available. Some bait products are toxic to other animals so be aware and follow any pesticide product directions carefully.   For more information:  https://extension.psu.edu>slugs-and-their-control  and https://content.ces.ncsu.edu>slugs-snails

responder: The Question Asker Replied July 03, 2024, 8:17 AM EDT
response: Thanks for your reply. I went out with a flashlight last night and there were no slugs anywhere.  What I found were brown beetles (see picture) on all the plants.  As they decimate one batch they move down the line to others.  My second picture shows our yard. The beetles started at the plants on/near the patio (thyme, sweet potato vine, yellow petunias, spearmint all in pots then attacked the salvias, both annual and perennials and sunflowers along the trees.  As those were decimated they came back to the patio and attacked the vinca in pots and the raised bed then moved back over by the trees to hit the vinca, a echinacea in a pot, then along the pool where there is both tall phlox and vinca.  I spent an hour and a half going up and down the beds picking them off and dumping them into soapy water.  A rather backbreaking process. What are these beetles and how do we get rid of them?

responder: The Question Asker Replied July 03, 2024, 8:25 AM EDT
response: Thanks for your reply. I went out with a flashlight last night and there were no slugs anywhere.  What I found were brown beetles (see picture) on all the plants.  As they decimate one batch they move down the line to others.  My second picture shows our yard. The beetles started at the plants on/near the patio (thyme, sweet potato vine, yellow petunias, spearmint all in pots then attacked the salvias, both annual and perennials and sunflowers along the trees.  As those were decimated they came back to the patio and attacked the vinca in pots and the raised bed then moved back over by the trees to hit the vinca, a echinacea in a pot, then along the pool where there is both tall phlox and vinca.  I spent an hour and a half going up and down the beds picking them off and dumping them into soapy water.  A rather backbreaking process. What are these beetles and how do we get rid of them?   Pat Kucek  On Jul 2, 2024, at 11:52 AM, Ask Extension <<personal data hidden>> wrote:   ﻿

responder: An Ask Extension Expert Replied July 03, 2024, 2:59 PM EDT
response: That was good sleuthing and productive work! You have been effective in reducing the next stage of laying eggs I think.  They are Asiatic garden beetles-a cousin to Japanese beetles. Except they do their eating damage at night as you've detected. Because the Asiatic garden beetle is attracted to light at night, perhaps an easier method (rather than hand picking with a flashlight) I've found says to construct light traps. "Hang a light bulb above a pan of soapy water. Because this beetle tends to feed close to the ground, it would probably be a good idea to place the pan of soapy water on the ground and the light bulb about six inches above it. Asiatic garden beetles are not resistent to pesticides. Sevin and other insecticides labeled for residential landscapes should give adequate control." This information came from:  https://content.ces.ncsu>asiatic-garden-beetle The life cycle of this beetle is like the Japanese beetle so you may want to control them at other stages. Removing weeds and tall grasses in the fall may help to deter the grub population.  The grubs are living underground generally in a lawn area where they can easily feed on grass roots. Nematodes are a safe and effective way to control grubs. Neem oil is also effective. Of course always follow the product instructions carefully.  Note that large amounts of pesticides kills many types of insects including our beneficial insects such as bees. This article explains in detail:   https://www.psu.edu>news>fayette>story>take-control and for further information:  https://ag.umass.edu>landscape>fact-sheets>asiatic-garden-beetle