A: First conspicuous sign of infestation is large quantities of “frass” which is the fibrous, excrement from the larval form of a tiny moth called the Palm leaf skeletonizer, Homaledra sabalella. This moth feeds mostly on tissue between veins or ribs of lower leaf surfaces of many palms to it will be difficult for any chemical to reach the larvae. This is the reason we do not recommend any heavy broad spectrum pesticides. The Palm leaf skeletonizer will also feed on leaf stems, disrupting vascular tissue and causing death of entire frond. Female moths lay batches of 36 or more eggs glued to the surface of older palm leaves and covered with brown, papery material. The larvae mine in groups on both the upper and lower surfaces of older leaves, under webs of silk. Excrement from the larvae is deposited on top of the silk. Pupation takes place in the larval mines. There may be up to five generations per year. Cutting and bagging or burning infested leaves is an effective method of control.
A: After talking to you about bringing a sample in a sealed plastic bag to the office, I was able to determine they were most likely Weeping fig thrips, Gynaikohrps uzeli. Since the plants at your nursery were originally brought in from South Florida, it was important for me to notify the Florida Division of Plant Industry plant inspector about spotting this insect pest. We do not want these insects to become established here as it is quite possible for the insects to feed on other landscape plants which could lead to some serious issues. Weeping fig thrips is a very large thrips compared to the flower and chili thrips we are more accustom to seeing in this area. They are dark black and can be plainly seen without the aid of a stereoscope or eyepiece whereas flower or chili thrips are best seen using magnification aids. Weeping fig thrips typically feed on the new leaves and cause them to fold onto themselves, covering the thrips. The feeding causes blotches on the leaves and can lead to pre-mature leaf drop. Chemical control is difficult but professionals have chemicals available with the appropriate pesticide license. Such products as Merit and Safari can be used as a soil drench (poured around the root area of the plant). This will allow the chemical to be absorbed through the roots and then the chemical will move to other parts of the plant eventually reaching every leaf. When the insects feed on the leaves they will take in the chemical and you should see some control in your nursery setting.
Thanks for bringing in a sample of the insect as there are two very similar looking. One is the Milkweed assassin bug and the other, the Giant Milkweed bug, Oncopeltus fasciatus. Yours was the Giant Milkweed bug which feeds in milkweed plants, preferentially the fl
ower buds and seed pods, which are rich in nutrients. Oncopeltus fasicatus lives out its life on milkweed plants. Mating, egg-laying, development of larvae, and courtship all take place on milkweed plants. The primary food is milkweed seed, while the insects also feed on milkweed plant juices. The milkweed diet makes the bugs unpalatable and they tell predators to stay away with their combination of red and black coloring. The species ranges from Ontario to South America, including the West Indies.