How Tiddi reads a district
Two kinds of evidence, never mixed: what survey teams found on the ground, and whether the weather would let locusts breed.
In short
- 12 districts
- India's Scheduled Desert Area in Rajasthan and Gujarat, where desert locusts arrive and breed.
- 14 days
- The oldest a survey can be. After that a district reads unknown, never clear.
- 100 km
- Locusts reported this close in the last 14 days, on either side of the border, and a district reads locusts seen.
- 25 mm
- Rain in 30 days that, with moist soil where eggs are laid, makes breeding possible. Weather, not a sighting.FAO Desert Locust Guidelines
Locusts or not
Field teams of the Locust Warning Organisation survey the desert and report what they find, including when they find nothing. Their reports reach FAO's Locust Hub, usually weeks later. For each district, Tiddi asks three questions, in this order, and stops at the first yes.
| Question | If yes, the district reads | Today |
|---|---|---|
| Has anyone reported locusts within 100 km in the last 14 days? | Locusts seen | 0 |
| Is the last survey here older than 14 days, or is there none? | Unknown | 12 |
| Otherwise: surveyed in the last 14 days and nothing found | No locusts seen | 0 |
A survey that finds nothing is real evidence: someone went and looked. But silence is not. The desert is large, the teams are few, and the record arrives late, so an old survey is treated as no survey. The district page always shows the date of the last one.
Breeding weather
Satellites can't see locusts. What the weather can show is whether they could breed: females lay eggs 10–15 cm down in sandy soil, and the eggs only hatch if that soil stays moist. So for each district Tiddi reads two things from the ECMWF weather model, on Maplore's own weather server:
- Rain over the last 30 days, all thirty of them. A missing day makes the total unknown, never a smaller number.
- Soil moisture at egg depth (the model's 7–28 cm layer), the latest hour.
| Band | Rule |
|---|---|
| Breeding weather | At least 25 mm of rain and soil at least 0.15 m³ of water per m³ |
| Some rain | At least 10 mm of rain, but not both of the above |
| Too dry | Less than 10 mm |
Rain decides the middle band, not soil. Over these desert soils the model's moisture sits near 0.2 even without rain: in September 2026 it read 0.23 for Jaisalmer after 2.3 mm in a month. A rule on soil alone called bone-dry desert "some rain". Soil only confirms rain that fell.
The thresholds follow the FAO guidelines in spirit. They are indicative bands for a public page, printed here so anyone can disagree with them.
Today's districts
Rain in the last 30 days, district by district, against the two marks: 2 with breeding weather, 8 with some rain, 2 too dry. Read 27 Sep 2026.
10 mm and 25 mmSoil: m³ of water per m³, breeding from 0.15
Across the border
India's locusts usually come from Pakistan and Iran: they breed on the coast and in Balochistan in spring, then in Nara, Tharparkar and Cholistan, against the Indian border, in summer. Pakistan's and Iran's survey teams report through the same FAO system. Each district also looks 300 km over the border for reports from the last 30 days, and a report within 100 km counts toward locusts seen just as an Indian one would.
Countries read: India, Pakistan, Iran, Afghanistan.
Wind paths
For twelve breeding areas in Pakistan and Iran, Tiddi draws where the wind would carry a swarm leaving today, over the next 3 days. The rules are FAO's figures for how swarms fly:
- By day only, 9:00 to 17:00 local time, and not below about 20 °C.
- With the wind at 850 hPa, about 1.5 km up (ECMWF forecast).
- No more than 130 km a day.
The paths are weather. A path is drawn in locust amber only when it starts from a group that was actually reported; every other path is a "what if".
What it can't tell you
- Where locusts are today. The newest survey is days to weeks old, and the LWO's bulletins every two weeks are often newer than the FAO record; Tiddi shows both, with dates.
- That a district is safe. "No locusts seen" means a team looked recently and found none, nothing more.
- A forecast. Breeding weather says eggs could survive, not that any were laid.
Tiddi is not an official LWO or FAO forecast. To report a sighting, call the LWO in Jodhpur on 1800-180-2111. Where each record comes from: Sources.