Caterpillars are becoming a problem in some areas now. Tent caterpillars have started eating crabapples, chockecherries, and some other ornamental plants. Watch out for a big nest of spider web looking material on branches. Early treatment will stop massive defoliation and limb die-off. Trimming nests out can work if caught early enough and if it will not damage the tree or make it unsightly. Here at Delaney’s we carry a full line of control measures. We have two organic products (Spinosad and Bt) that will knock those insects out quickly. Our triple action insecticide made with pyrethrins and neem oil is not quite as organic as the previously mentioned insecticides, but is just as well working. Traditional chemical control using Sevin or Malathion can be used as well.
Other caterpillars out now include leaf rollers and leaf eaters. Leaf rollers can be found on many fruit trees, roses, and various other ornamental trees and bushes. They can be mistaken for aphids as both of them will cause a leaf to curl inward. Opening up the leaf will normally produce a little caterpillar or maybe just some webbing if the critter is already gone. If their numbers get high leaf rollers can devastate a tree and cause much unneeded stress on plants. The above mentioned insecticides will work well on these as well. The only difficulty is you need to get the spray in the leaf so a good drenching is needed.
Leaf eaters usually leave small holes in the leaf or can take irregular notches out of leaf margins. Some holes may be very small. Also some leaf eaters can be voracious eaters and eat entire leafs and leave nothing left. These are what to really watch out for. They can defoliate a whole branch in days! Luckily infestations of this type are rare, but always keep an eye on your landscape! Again Bt and Spinosad will control these insects easily. Circular holes on leaf margins are usually caused by leaf cutter bees.
The last problem I would like to address is spider mites. These are showing up now as well with the onset of hot dry weather (which they love). These can creep up on the homeowner quickly as well. The damage starts with yellowing leafs and we call a mottled look. This looks like very small yellow dots on the leaf surface. When all the little dots come together the whole leaf will be yellowish and fall off. This is cause by the feeding of the mites. They tear up the leaf and eat the juices that come out. Now because mites are arachnids not insects most insecticides will not control them. Neem oil and other horticultural oils are labeled for mites. These are contact pesticides which means you have to get it on the pest. So you have to spray the underside of the leaf surface to get good control. I recommend a follow up spray after 3-5 days to kill any mites that have hatched out after the first spray. Caution must be used with these oil based products in hot weather to avoid harming the plant and remember to always read the label before applying any pesticide.
Two Spotted Spider Mite (not life size!)