Does it start out as a root eating grub like some other critters?
I see Japanese beetles hatching or digging in to lay eggs mostly at night.
Nematodes seems to have solved my problem for a few seasons.
There was a time when I checked my pots during the day to find several plants laying down all of a sudden.
When I emptied the pot I found as many as 60 grubs in a true 20 gal. pot.
After 1 nematode spray of all my pots I haven't seen a grub or cutworm in a few years.
I think the Pupa is in soil for some but don't know about the grub stage.
I'd think that it is like the japanese beetle.
Googled it-
What Do Weevils Eat?
Weevils feed on plants in the larval stage and as adults. Some weevils can be very destructive to crops. For many years, one of the most destructive weevils was the cotton boll weevil. The
black vine weevil,
Otiorhychus sulcatus (F.), is found in many parts of the United States. It feeds on a variety of plants, including hemlocks and rhododendrons.
Most weevils are found in fields, gardens or orchards. A few weevils attack stored grains and seeds. They can be very destructive, and their damage is often very expensive. The most common stored product weevils are the rice weevil,
Sitophilus oryzae (L.), the granary weevil,
Sitophilus granarius(L.), and
the cowpea weevil,
Callosobruchus maculatus (F.).
However, a few weevils become structural pests. These are the weevils that upset homeowners because they invade homes—often in great numbers. Some of them invade in the fall. They hide during the winter and leave in the spring. Others invade in the summer when the weather starts turning hot.
Weevil Life Cycle
Life cycle of weevils depends greatly on the species. For some, in spring, the adult weevils lay their eggs on the ground near the host plant. When the eggs hatch, the larvae burrow into the ground and feed on the roots. Since the larvae are underground, people seldom see them.
Many of the larvae spend the winter in the ground and emerge as adults the following spring. However, the adults that emerge during the summer or fall may invade homes for shelter. Some, like the Asiatic oak weevil, are attracted to light, so they are drawn to homes at night. Others may be attracted by the warmth from the house.
Nasty guys for roots and plants in most any stage.
Didn't mean to Hyjack the thread.
We want details. 
