What kind of Caterpillar? How Do I Destroy?

Lake Forest, CA(Zone 10a)

I started a thread the other day regarding these plague proportion monsters eating everythin in my garden- what are they?

Thanks

Thumbnail by croclover
Lake Forest, CA(Zone 10a)

Look at the incredible damage these things are doing to my morning glories. I think I need a strong remedy- any suggestions? Does the Rescue Trap that lures moths work for this kind?

Thumbnail by croclover
Acton, TN(Zone 7a)

It's a looper and since it's eating beans my guess is a "Soybean Looper"
http://www.utextension.utk.edu/fieldCrops/soybean/soybean_insects/photogallery.htm / http://www.utextension.utk.edu/fieldCrops/soybean/soybean_insects/photogallery.htm .
-- Cabbage looper (which is more common) looks the same but I don't think it bothers beans. Maybe you have those, too? Dipel (BT) or Bulls-Eye should work and not hurt other beneficials (except butterfly larvae).
http://www.gardensalive.com/product.asp?pn=8756&ss=bulls-eye

Griffin, GA(Zone 8a)

I second the Bt suggestion unless you are trying to use your morning glories as a host plant for any other caterillars.

Union City, CA(Zone 9b)

Depending on where plant is , you can put out bird food [ seeds - micro-way 2 minutes on Hi - you don't want volunteers ] or a pan disk of water for birds . They will probably deposit seeds - but will eat any buds they see .
It is probably hot enough where you are for the birds to be looking for water .

Kalispell, MT(Zone 4b)

I had those and hand picked and squashed every one because in one day they can eliminate a whole plant. I just put on a pair of gloves and pinched them right on the leaf. Take that and die you miserable nighmare of a worm, die, die,..........

Stephenville, TX(Zone 8a)

It is indeed a looper, but hard to tell which one. The two already mentioned both occur in CA along with a third, the alfalfa looper, which this resembles as well. See:
http://mint.ippc.orst.edu/looperid.htm
for a comparison.

All three species have large host ranges and aren't limited to any one group of plants. Like most caterpillars, they do 95% of the damage in the last two life stages or instars. This means that they are often unnoticed until they have gotten big and voracious. Bt products are very effective against all loopers, however the older they are the less susceptible they are. Further, the bacteria have to be eaten to be effective, which means there is going to be some more damage from the biggest eaters. There are at least four toxic entities produced by Bt and the crstal toxin (delta endotoxin) is the most effective and fast acting. If a Bt treatment is going to work, it normally will stop larval feeding within a couple of hours. Within 24 hours, the gut is paralyzed and then it is pretty much over. Bacterial cells are growing and penetrate the crystal compromised gut, causing the larva to blacken (or sometimes just dry out) and dissolve. In the interval between gut paralysis and death the larva is not going to look very different from an untreated larva. The big difference is that it is not eating.

When treating with Bt, getting good coverage is important. Some liquid formulations contain stickers and spreaders to get the spray over the leaf and keep it there. Although UV rays inactivate Bt very quickly, treating in the evening will avoid most of the problem. Some products come with stickers/spreaders/sunscreens, others do not. There are some home-made recipes for these, but I don't know how effective they are.

Finally, although Bt is toxic only to the insect, the inert ingredients can cause allergic reactions if the product is not used according to the label. This is especially true of dry formulations that can be inhaled during application, although the liquid mist can do this as well. It's rare, but I know of two instances where it has happened - one dry in a greenhouse and one liquid in a pecan orchard.

The goal of this ramble is not to discourage, but to point out that using Bt, especially against large larvae, has some drawbacks that you need to be aware of and plan for. Nothing is more disappointing than to have a treatment fail or for the critters to keep eating like nothing is wrong when in fact you are on the verge of successfully stopping them. In your case, the hand-picking that was recommended might be best, followed by Bt as a backup to get what you missed. If another generation starts, try treating them before they are 1/2 inch long. Bt is deadly on the early caterpillar stages.

-FM

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