Sunday, October 13, 2013

Insect pests: Flea Beetle and 26 Spotted Ladybird

 Every second year or so I grow a small crop of potatoes, last time it was 'Red Pontiac' , as above, and this year it is 'Dutch Cream'.
 They are just coming into flower but as it has been a hot dry spring a couple of insect pests are starting to make their presence felt.
 The 3mm metallic flea beetle (Xenidia picticornis ,Halticinae) pictured here, has very stout femora of the hind legs which means it is able to jump out of the way when disturbed. They leave tiny shot holes in the leaves but do not reduce crop yields. Other edible plants which are more seriously affected by flea beetles include beans, basil, mint and rhubarb as well as ornamentals such as Plectranthus species. They lay their eggs on the stems of plants and the resulting larvae may bore into the stem when feeding resulting in wilting of the affected parts. They require a systemic insecticide for adequate control and to break the life cycle.

The twenty-six spotted ladybird (Henosepilachna sparsa vigintisexpunctata) and the closely related twenty-eight spotted ladybird (Henosepilachna virgintiopunctata) are garden villains active from October to April. They relish the leaves of potatoes, cucumbers and rockmelons as well as ornamentals such as Brugmansia or members of the family Solanaceae. These beetles are oval in shape and about 6mm long making them larger and  easily distinguishable from the small 'good guy' ladybirds which feed on aphids.Their larvae feed on the underside of leaves and they are covered in burr like spines.They may be present at the same time as the adult beetles feeding on the upper surface and if the infestation is severe the leaves may appear as if burned and collapse.
If your crop is small, as is mine, they are easy to remove by hand as they don't budge when
approached. Too busy producing the next lot of offspring as is the case in the middle photo above.

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