1. Dr. S.K. Dutta & Dr. Badal Bhattacharyya Department of Entomology
Identification, symptoms and nature of damage: white grub, mole cricket and ants
Dr. S.K. Dutta & Dr. Badal Bhattacharyya
Department of Entomology
Assam Agricultural University,Jorhat-13

2. White grubs: Identification:
The adult beetles are dull brown, reddish or black in colour
The larvae are “C” Shaped, white in colour with brown head and prominent thoracic legs. The grubs are generally found in the upper 5 to 10 cm layer of the soil
Video: grubs of scarab beetles
Video: Adult scarab beetles
Source: AINP on White grubs, Department of Entomology,
Assam Agricultural University, Jorhat-13

3. Symptoms:
The damage becomes evident only when the entire potato plants dry up due to the grubs feeding on fibrous roots
Fig. White grub infested potato plants
Source: AINP on White grubs, Department of Entomology,
Assam Agricultural University, Jorhat-13

4. Nature of Damage:
Initially young grubs feed on mother tuber, roots of developing potato plants
After tuber formation, the older second instar and third instar grubs feed on the under ground potato tubers by making large, shallow and circular holes into them and thus rendering them unfit for marketing
They live concealed while feeding on tubers, and the plants continues to grow normally without any reflection of injury on aerial parts

5. Fig. White grub infested potato tubers
Source: AINP on White grubs, Department of Entomology,
Assam Agricultural University, Jorhat-13

6. Mole cricket: Identification:
Adults are cylindrical, nearly cm long and dull brown. Mole crickets have front legs enlarged, shovel-like and modified for digging
They fly at night, can run quickly, but are poor jumpers.
Nymphs resemble adults but are smaller and do not have fully developed wings
Fig. Mole Cricket
Source: AINP on White grubs, Department of Entomology,
Assam Agricultural University, Jorhat-13

7. Symptoms: Cutting of seedlings and tunnelling in the soil
Fig. Tunneling in fallow land by mole cricket Fig. Tunneling in field after sowing
Source:

8. Nature of Damage:
Mole crickets can damage potato plants by feeding at night on above ground foliage or stem tissue and below ground on roots and tubers
Seedlings may be girdled at the stems near the soil surface, though some plants may be completely severed and pulled into a tunnel to be eaten
Mole cricket tunneling in the upper 25 cm of the soil dislodges plants or causes them to dry out. Reduction of plant stand is common
Fig. Potato tubers infested by mole cricket
Source: AINP on White grubs, Department of Entomology,
Assam Agricultural University, Jorhat-13

9. Red ant: Identification:
The red ants are reddish in colour and measures cm in size
Fig. Red ant
Source: AINP on White grubs, Department of Entomology,
Assam Agricultural University, Jorhat-13

10. Symptoms: Potato tubers show minute holes on the entire surface
Fig. Potato tuber infested by red ant
Source: AINP on White grubs, Department of Entomology,
Assam Agricultural University, Jorhat-13

11. Nature of Damage:
This ant attacks plant parts that are mostly underground
Red ants are serious phytophagous pest of potato making galleries in tubers and their attack is characterised by presence of minute holes on the surface of tubers