Lavender can be affected by a number of insect pests, but only a few cause economic damage to the crop on a regular basis, such as the four-lined plant bug. However, under the right conditions, other insect pests can reach damaging levels. That is why it is important for growers to constantly scout fields and identify localized pest issues before they become a major issue.
In one of the provincial lavender cultivar trial locations, we noted major damage over the past week by garden fleahoppers (Figure 1). A section the trial containing about 100 plants had significant damage to almost all of the leaves on the plant. When the plants were shaken, hundreds of small green nymphs and a few adults fell out of the plant. Damage from garden fleahoppers has been noted on lavender before, but not at the damaging levels noted in this field.
Garden fleahoppers are true bugs that suck plant juices out of the leaves and stems, much like four-lined plant bugs. Instead of the distinct circular brown lesions of four-lined plant bug, garden fleahopper damage appears as smaller irregular white discoloured areas of the leaf (Figure 2). In the cultivar trial, the leaves in severely affected areas appeared silvery instead of green because of the severe speckling. These leaves will likely die over the next few weeks and are already turning yellow. Adult garden fleahoppers are small (2 mm) black hopping insects with large hind legs (Figure 3) similar to flea beetles. Nymphs are green but have the same large hind legs and hopping characteristics of the adults (Figure 4). They are best identified by shaking the plant over a piece of paper or other flat surface and watching what falls out on the paper. If insects are seen, disturb them to see if they hop away. There are no other known insect pests of lavender that hop in this manner. Hundreds of insects may fall out of severely affected plants.
If garden fleahoppers are seen in low populations in a field, they are unlikely to cause economic damage. They should be watched over time, but no immediate corrective action is necessary. For more severely affected plants, insecticidal soaps may provide some suppression, but it is unknown if the level of control warrants the cost of application. If only a few plants are affected, spraying these plants several times may control the population enough to prevent spread to neighbouring plants.