|Figure 1. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.|
Give priority to following factors when selecting monitoring sites:
□ Choose fields and sections of the fields with past or present damage symptoms.
□ Choose fields that are well irrigated (leaves are dark green in color), including young, lush crops. Areas of a field that are under stress and not as lush (yellow) are less likely to support CLB.
□ Monitor fields located along riparian corridors, roads and railroads.
□ Survey field areas that are close to brush cover or weeds, easy to access, or are nearby sheltered areas such as hedge rows, forest edges, fence lines, etc.
Focus your site selection on the following host plant priorities:
□ First - winter wheat. If no winter wheat is present then;
□ Second - other cereal crops (barley, wheat, oats, and rye). If no cereal crops are present then;
□ Third - hay crops. If no hay crops or cereal crops are present then;
□ Fourth - ditches and water corridors
Sweep-net Sampling for Adults and Larvae:
● A sweep is defined as a one pass (from left to right, executing a full 180 degrees) through the upper foliage of the crop using a 37.5 cm diameter sweep-net.
● A sample is defined as 100 sweeps taken at a moderate walking pace collected 4-5 meters inside the border of a field.
● At each site, four samples should be collected, totaling 400 sweeps per site. The contents of each sample should be visually inspected for life stages of CLB and all suspect specimens should be retained for identification.
● Because the CLB larvae are covered in a sticky secretion, they are often covered in debris and are very difficult to see within a sweep-net sample.
● To help determine the presence of CLB, place the contents of the sweep net into a large plastic bag for observation.
Both the adults and larvae severely damage plants by chewing out long strips of tissue between the veins of leaves (Fig. 1), leaving only a thin membrane. When damage is extensive, leaves turn whitish.