Insect Pests of Vegetable, Ornamental and Spice Crops (2+1)

Blister beetles

3. Blister beetles, Mylabris spp. (Meloidae: Coleoptera)

• Distribution: Africa and south-east Asia.
• Hosts: Cururbits, okra, cotton, carnation, rose, groundnut, beans, millet etc.

Damage:

• Caused by the adults only
• Feed on the floral buds and flowers
• Attacked flowers become brownish and unattractive
• Larvae are beneficial
• Grubs feed on the eggs of various grass hoppers and locusts found in the soil

Identification

• Full grown grubs are coarctate and form pseudopupae, which become pupae later
• Beetles have three black and three yellowish orange bands running transversely and alternatively on elytra.
• Among different species, M. pustulata are the biggest (22-26 mm), M. phalerata are slightly smaller (20-24 mm) and has its yellowish red bands narrower than black bands.
• Beetles of M. mecilenta and M. tiflensis are relatively smaller in size than the earlier two species.

Salient features:

• The eggs are laid in soil of cultivated fields.
• Full grown grubs are coarctate and form pseudopupae, which become pupae later.
• Adults emerge from soil in August and remain active till December
• Beetles have three black and three yellowish orange bands running vertically and alternatively on elytra
• When handled, beetles exude an acrid yellow fluid which contains, cantharidin
• It is irritant to touch and cause blisters on human spin, hence the common name.

Management

• Hand picking and destroying the beetles during morning hours when they are less active is effective.
• During severe infestation the crop can be sprayed with deltamethrin (0.0028%) or carbaryl (0.1%) at 10 days interval.