Harlequin bugs can be a problem after mild winters, but low densities are unlikely to cause damage which will be regained economically by insecticides.
Harlequin bugs are shield-shaped flat bugs, easily identified because of their bright, shiny black and red coloration. The triangular plate on the top of the thorax is black with a cross shaped mark of red in the center. Harlequin bugs smell bad at all life stages.
Harlequin bugs overwinter mostly as adults in our area, hiding under crop residue and in other protected sites. They become active in mid-spring and begin the feed on wild crucifers. They move into crop stands by early summer, and begin to lay eggs on leaves. After hatching, harlequin bug nymphs usually remain on the same plant, feeding for about two months before becoming adults. Unless the weather remains unseasonably warm, only one generation occurs per growing season.
Harlequin bugs feed by sucking sap from crucifers. If young plants are fed on, the growth is distorted and slowed, and the growing point may die. Plant tissue around the feeding sites often turn cloudy. Harlequin damage is more likely after mild winters.
Cultural Control
Crop residue should be destroyed immediately after harvest to reduce local populations. Other cover, such as vegetation near field edges should be reduced to minimize overwintering success.
The cabbage varieties Copenhagen Market 86, Headstart, Savoy Perfection Drumhead and Early Jersey Wakefield; the cauliflower varieties Early Snowball X and Early Snowball Y, and radish varieties White Icicle, Globemaster, Cherry Belle Champion, Red Devil and Red Prince have all been recognized as resistant to harlequin bugs.
Harlequin bugs are subject to attack by some predators, but have developed effective chemical defenses of their own. If harlequin bugs are controlled with insecticides, however, natural enemy populations of other more important pests, such as aphids and caterpillars, will be disrupted.
Product List for Harlequin bugs:
|
Insecticide |
Product per Acre |
Preharvest Interval , remarks |
|
Thiodan 3E, Endocide 3E Thiodan 5OW |
1-1.3 qt 1.5-3 lb |
(7 days) Some rotational restrictions with root crops. Proposed 48 hour reentry interval. Chlorinated hyrdrocarbon insecticide (endosulfan). |
|
Sevin XLR+, 4F Sevin 80S Sevin 5OW |
1-2 qt 1.25-2.5 lb 2-4 lb |
(3 days) A carbamate insecticide (carbaryl). The 80S, 4F, and 5OW formulations are highly hazardous to bees. Some rotational restrictions. May be used with sprinkler irrigation. 12 to 24 hour reentry proposed. |
|
Sabadilla dust |
as labelled |
A botanical insecticide that is allowed for use in Colorado Certified Organic production. |
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Cole crops, Insects, Harlequin bugs
Date: 01/08/1998