Native budworm adults
Heliothis (Native budworm)
Native budworm/helioth s larvae — range of colours
The native budworm, or heliothis (Helicoverpa punctigera), generally attacks lucerne during spring and early autumn. Eggs are laid singly on the leaves and the larvae grow to maturity in two or three weeks. Larvae vary from dark brown to pale green, with stripes along their bodies.
Most larvae in lucerne never reach the pupal stage; they are invariably killed by an insect virus disease. Infected larvae at death are soft and rupture readily, oozing dark liquid over the leaves.
Spraying is unnecessary where there are high numbers of diseased larvae, as they die anyway. Spraying is recommended when at least one-in-ten stalks hosts a healthy, medium to large sized larva, i.e. larger than 10 mm long.
.
.
Black cutworm — larvae and damage
Cutworms
Cutworms (Agrotis spp.) are moth larvae which shelter in trash and soil during the day and feed at night. Indicators of cutworm activity are thinning seedling stands and plants cut off at ground level. Their presence can be confirmed by digging at the base of plants to reveal large, soft-bodied brown larvae. The larvae are readily controlled with insecticides. Insecticide should be applied late in the day or at night for best results.
.
.
Crown borers
Crown borers (Zygrita diva and Corrhenes stigmatica), are normally pests of old lucerne stands. The larvae tunnel and feed in the crown,sometimes killing the plant. Current insecticides are not a practical solution; heavily infested stands should be ploughed out.
Zygrita crownborer adult - oviposition lesion
Lucerne crownborer larva and damage
Corrhenes crownborer adult
.
.
