Curculio elephas
In 3 days ~10% in a week ~20%
Curculio elephas is a species of beetle in the family Curculionidae, the true weevils. It is known commonly as the chestnut weevil. It is a serious pest of chestnut (Castanea sativa) in Europe. Curculio elephas are similar to Curculio sayi and Curculio caryatrypes in the United States.
Adults feed on chestnut foliage until nut kernels enter the dough stage in mid to late August. Although they can lay eggs any time after kernel filling, most eggs are laid after the bur begins to open. The adult female weevil drills a hole in a chestnut fruit and deposits one egg inside. The eggs are laid into the cupules or around the peduncle joints. Eggs hatch in five to seven days producing large, legless grubs. When the larva emerges from the egg it feeds on the developing chestnut. The larvae leave behind frass and excrement. Infested nuts may contain several weevil larvae or weevil burrows filled with excreta. Upon chestnuts fall, the larvae chew their way out of the nuts and retreat into the ground. They immediately bury themselves several centimeters deep in the soil. The following July, the larvae turn into pupae. Pupae may be in the soil for one season or for several years... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cévennes National Park | 🇫🇷 France | |
| 2 | Pyrénées National Park | 🇫🇷 France |
Rare
Under 5% of wildlife watchers report a Chestnut Weevil sighting in Porto on a given day, based on 6 verified sightings from GBIF citizen-science data. It is the 422nd most-seen of the 498 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
August
In that month about 10% of wildlife watchers report a Chestnut Weevil in Porto on a given day, against under 5% in September to July, the lowest months. That is one of Porto's driest months, with about 20 mm of rain against 140 mm in January.
Between 10 pm and 1 am
Across all the parks we cover, that three-hour window holds the most Chestnut Weevil sightings with a recorded time, and about 7 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
5th of 6
Of the 6 cities where we can rate Chestnut Weevil sightings, Porto ranks 5th at under 5%. The best odds are in Berlin (Germany, about 10%), Hamburg (Germany, about 10%) and Paris (France, under 5%).
GBIF citizen-science records
It is estimated from how often the Chestnut Weevil is recorded against all the insects logged in Porto (6 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
