Leaf Beetle, Flea Beetles
An extensive family of beetles, Leaf Beetles have an enormous appetite. Of course, some species of flea beetle are more damaging than others. Sometimes they're called Flea Beetles because they tend to jump from leaves when disturbed. Many are shiny, metallic or iridescent.
Will leave numerous small holes in leaves.
Flea Beetles have a handful of natural enemies that can help control their numbers.
Adults: Mature beetles active spring to summer. The adult beetle is normally metallic or brightly coloured. They can measure 3mm to 1cm. Adults can jump when disturbed. Larvae are active late spring to summer. The larvae resemble a small caterpillar which is black in colour 3mm to 5cm in length. Pupating in the soil and emerging as adults to feed on the host plant, before hibernating during the winter months.
Small holes in the leaf and shoot tips. Small brown patches on the leaf surface. Leaves have a 'peppered' effect where beetles have taken bites. Seedlings are at most risk. Beetles will jump away from leaves. Grubs can attack the roots but this doesn't seem to be detrimental to the plant, so can be tolerated. Heavy infestations stunt growth.
Hand removal if a minor infestation. Doing so with care as if you bump the plant they beetle will jump off in the soil. Incorporate yellow sticky traps to monitor your garden population. Try to ensure seedlings grow and become established quickly. Older plants are more resistant to the damage. Floating row covers are perfect for covering seedlings until plants become established enough to withstand the damage. Cultivate the soil around the plant to expose pupa and fallen beetle to wildlife to feed. Keep the growing media damp and moist as the beetles prefer a dry environment. Clear away fallen leaves and cultivate around the plant to remove hibernation opportunities for the beetles. Neem oil, or homemade insecticidal soap, can be sprayed onto the leaf surfaces. Make sure to follow guidance for neem oil and to test treat before applying to the whole plant. If available, beneficial nematodes watered into the soil media will attack the larvae that develop in the soil. This will rid of the pests attacking plant roots, and reduce the number that develops into adults. Alternatively, Flea Beetles are eaten by ladybugs and predatory wasps. Attract beneficial insects into your own green spaces by planting an array of indigenous plants, incorporating bug hotels, or just by letting some areas grow a little wild!
Organic pyrethroids can give good control, but should only be applied to foliage and not to flowers. The chemicals are unselective and will kill any insect that comes into contact with it. If you intend to eat your yield, be sure your crop is stated on the bottle label. If you ever feel unsure, please consult with your garden centre or ask the Candide community!