2026-09-22

Hairy caterpillar attack

Started noticing Hairy caterpillar(Eupterote mollifera) moving around the front garden yesterday morning. Wondering about the source, i looked at our moringa tree. It looked quite healthy, except for very minor damage. Then i looked around and realized that the moringa tree in the empty plot opposite across the road has been nearly defoliated.

Based on past experience, i started searching for more and found few more of various sizes in the front garden area. I killed all of them and started reading about the control measures to take.

A summary of what i found about the them is given below:

Hairy caterpillars are the 2nd stage in a moth's lifecycle. They are voracious eaters and nocturnal in nature.
Baby caterpillars can be carried by wind upto 100's of metre.
Once the adult stage is reached, the moth can fly and lay eggs below the leaves and give rise to next generation.
Caterpillars eat the moringa leaf during night and comedown during daytime to avoid the heat. To avoid heat, they can even drop down to the soil below. When the heat reduces in the evening they climb up again the next to continue their hunt.
Since the congregate in the bottom most part of the trunk in the daytime, it is the best time to kill them enmasse either by burning or by pouring soap water.

The following control measures suggested by Claude were adopted.

A trunk collar/band was tied at the bottom part of the trunk using a polythene covered. The cover was covered by grease for around 2 inches breadth. The barrier is supposed to prevent the crawling caterpillars from climbing up from the soil. Whatever has gone up already get to enjoy their stay there.

I got a small amount of grease for ₹20 from the local auto mechanic Rajesh. This seems to be effective as i could see a caterpillar returning back to the soil after going around the trunk yesterday night itself. This morning i could see few caterpillars crawling around the front garden, but no new damage appears in the tree.

The second suggestion was to put up a light trap to capture the adult flying moth during the night time.

This was also setup in the first floor balcony, safely away from rain.

A bulb was suspended right over the soapy water in a tub at around one feet above the surface. The tub was placed on a stool at a elevation so it was above the open railing with a view out over the moringa tree at a distance of around 10 ft. The affected tree on the opposite plot is atleast 25 ft away from both light trap and our moringa tree. The stool is around 5 ft inside the covered balcony.

This morning not even single moth got captured. Will continue this for some time as it roughly takes 2–3 weeks for the moths to complete their lifecycle.

References:

Note:

The last two references talk about ballooning/silk-dispersal and grease-band-trapping. Those researches are specifically on bagworms (Thyridopteryx ephemeraeformis), a different species used as the general reference for how ballooning and sticky barriers work in Lepidoptera larvae broadly.