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Problem: Squash Bugs - Anasa tristis
Hosts: Squash and pumpkin
Description: Squash bugs are 'true bugs' which utilize their piercing sucking mouthparts to remove plant juices. Squash bugs generally occur on well-established plants (as opposed to being a pest of seedling plants).
Adult squash bugs move to plants from various adjacent (and sometimes within field) protected overwintering sites. Adult females deposit brownish-red eggs in clusters on a lower leaf surfaces. Newly emerged nymphs are small and greenish with black legs. Studies have shown that (in Kansas) first generation adults deposit eggs for a second generation, the adults of which overwinter.
High squash bug populations can literally drain plants causing them to die and wilt. Reduced yields and poor quality fruit may result from squash bug feeding activities.
Recommendations: Squash varieties resistant to squash bugs include Butternut, Royal Acorn, and Sweet Cheese.
Effective control of squash bugs is contingent upon timely insecticide sprays coupled with thorough coverage. Observe plantings for the presence of adult bugs and scout fields for egg masses on the undersides of leaves. Eggs get darker in color just before hatching. Treat when most eggs have hatched and when nymphs are still small to medium in size. Placing pieces of board or shingles on the ground near the plants concentrates these insects in a small area that is more easily treated. Adult squash bugs have a hard, protective shell which is impervious to insecticide treatments.
Use high pressure when applying liquid insecticides to ensure penetration of the dense plant foliage and thorough coverage to the nymphs which often are on the undersides of leaves. Using a duster will also work. Subsequent treatments are usually required due to the continual presence of egglaying squash bugs. Carbaryl (Sevin) and permethrin (Hi-Yield Garden, Pet & Livestock Dust, Ortho Bug-B-Gon Multi-Purpose Garden Dust, Green Thumb Multipurpose Garden and Pet Dust)
It is especially critical to reduce the overwintering population of squash bugs by
working the soil and/or removing foliage and fruit immediately after harvest. This
deprives nymphs of the necessary food source to complete their development. Also, recently
formed adults are denied a food source with which to build up the sufficient amounts of
body food reserves required to see them through winter.
References:
1. Pumpkins, K-State Research and Extension Publication, MF-2030, pg 8
2. Ortho Problem Solver, Ortho Information Services, pg 717
3. Squash Bug, Ohio State University Extension Factsheet, HYG-2141-88
Last Update: 04/03/2003
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