I checked the oleander plants to find not just one but several of the polka-dot wasp moth caterpillars, At this stage though they are commonly called the oleander caterpillar (Syntomeida epilais). As you can see from the photos below, they eat the entire leaf and can easily strip the leaves of an oleander bush in a few days.
If you see them, the IFAS site says their hairs are not stinging so handling them is not painful. I didn’t bother to find out if the hairs sting or not. I sprayed the entire bush to make sure I didn’t miss any of the younger stages hiding under a leaf somewhere on the bush. I have other plants in the garden specifically for feeding caterpillars, and I don’t want to harm any of the butterflies or bees in the garden, so I sprayed carefully making sure to avoid spraying anything other than the oleander bushes.
This lovely visitor, Syntomeida epilais commonly called the polka-dot wasp moth or oleander moth, is sitting on a Christmas cactus on the patio. I hadn’t seen one before, so I took the photo and then researched to see what it is. I learned it is unusual in that it emits a sonic sound to attract mates instead of attracting them by releasing scent and it is active during the day not at night like most moths. (see An Exception to the Rules and Oleander Caterpillar)
Now that I know what it is, I realize I saw one of the caterpillars, orange with black bristles, a few weeks ago sitting on a leaf of an oleander plant (see image). At the time I thought it was a Fritillary caterpillar (see image) which is also orange with black bristles. A few of the polka-dot wasp moth caterpillars can strip an oleander plant in a few days. They eat the entire leaf and not just the underside of the leaf as many caterpillars do. The oleander is a common plant in Florida and not always valued when planning a garden, but I enjoy the deep pink of the flowers just off the patio. I don’t want to lose them, so I’ll have to keep an eye out for larvae.
I captured this photo of a gulf fritillary caterpillar yesterday. The gulf fritillary butterflies are common in the garden, but this is the first time I have photographed the caterpillar. According to the IFAS website, the butterfly overwinters in Florida and migrates north in the spring.
The photos below show a gulf fritillary butterfly on a duranta skyflower and on flowers at a garden shop.
Diagnosing and treating problems in a garden is a continuous learning process. Next year I will know that a black spot on a tomato indicates that the invasion has begun. Next year when holes start to appear on the tomato leaves, I will know where to look and what to look for. I finally found the cause of the problems, a caterpillar hanging on the underside of a branch, a southern armyworm. The nasty caterpillar in the photo and his friends that have appeared since then are large enough to pull off, but I have also treated cherry tomato plant with BT (Bacillus thuringiensis). BT is a microbial insecticide.
The organisms used in microbial insecticides are essentially nontoxic and nonpathogenic to wildlife, humans, and other organisms not closely related to the target pest. The safety offered by microbial insecticides is their greatest strength.
The toxic action of microbial insecticides is often specific to a single group or species of insects, and this specificity means that most microbial insecticides do not directly affect beneficial insects (including predators or parasites of pests) in treated areas.
Because their residues present no hazards to humans or other animals, microbial insecticides can be applied even when a crop is almost ready for harvest.
Because a single microbial insecticide is toxic to only a specific species or group of insects, each application may control only a portion of the pests present in a field, garden, or lawn. If other types of pests are present in the treated area, they will survive and may continue to cause damage. Conventional insecticides are subject to similar limitations because they too are not equally effective against all pests. Nonetheless, the negative aspect of selectivity is often more noticeable for microbials.
Heat, desiccation (drying out), or exposure to ultraviolet radiation reduces the effectiveness of several types of microbial insecticides. Consequently, proper timing and application procedures are especially important for some products.
Special formulation and storage procedures are necessary for some microbial pesticides. Although these procedures may complicate the production and distribution of certain products, storage requirements do not seriously limit the handling of microbial insecticides that are widely available. (Store all pesticides, including microbial insecticides, according to label directions.)
I’m trying to use organic methods, but the reality is that sometimes I have to do something or give up the plant to the pests. BT does not instantly kill the caterpillars, but there is less activity until the caterpillars die in 2-3 days.
I continue to research solutions to problems, but more importantly what I am doing is learning to recognize problems so that next year I will anticipate the problems and will be ready with solutions faster. Luckily I started with a small vegetable garden this first year in Florida. I would be more frustrated than philosophical about the loss of vegetables to the pests if I were managing a larger garden. The smaller size allows me to regard this as a year of learning, not a year of “farming”. In the meantime, we enjoy the tomatoes, ochra and radishes plus the herbs that we have harvested, and we are happy that everything we have eaten so far was organically grown without application of pesticides.