As the warmer months approach, so does the threat of damage and loss of seedlings from chewing insects. With evening temperatures increasing, so will the activity of nocturnal chewing insects such as sowbugs, earwigs, caterpillars, slugs and snails. The threat of these pests occurs more commonly where renovation or development of landscape is on or adjacent to existing older ground cover. These are sheltered areas that harbor pests during the daylight hours.

There is an assumption throughout the industry that “sowbugs” live on dead and decaying plant matter. This is not completely true. It might be stated that once the availability of young and juicy vegetation is depleted they resort to eating dead and decaying plant matter. It might also be noted that they nest in dead and decaying plant matter, and in the process of nesting they will eat some of the decaying tissue. Sowbugs have never really been classified or recognized as harmful chewing pests. We should reconsider our attitudes and assumptions towards this particular pest.

In field observations we have seen them literally mow down acres of one and two day old seedlings in a matter of forty-eight to seventy-two hours. Rancho del Oro in Oceanside, CA was one project in particular, on a large scale, that the sowbugs (and snails) were directly attributed to the devastation of several acres of newly seeded slopes. One cannot fully assess the damage by sowbugs from casual observation after a project has “apparently not germinated” in a seven to ten day period. At Rancho del Oro, devegetation occurred within 24 hours of germination.

Once you’ve seen the destruction from sowbugs, you come away with a different attitude about their destructive eating habits. It’s hard to acknowledge the force in such a small, seemingly harmless creature, but there is power in numbers. You might see a few by day, but you can bet there are hundreds by night. We’ve seen virtually dozens in a one square foot area when they were on a feeding frenzy in the evening. If not total devastation, the damage can give an overall appearance of being too light or thin and total destruction will only be a matter of time.


We don’t know how far these pests will travel from their hiding places, but we do know that, especially during the dry summer months, they are attracted by moisture from irrigation. Whereas the seeded area might be free of debris or shrubbery for shelter, sowbugs, snails and slugs can move in from neighboring hiding places to forage in the evening hours.

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Preventative preparation saves time and money for those costly call backs.

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Once a potential pest problem has been recognized, preventative measures must be taken. Pesticide applications are necessary. Product recommendations should be made by a qualified, licensed pest control advisor. We have found granular materials as opposed to liquid pesticides to be more suitable in hydroseeded areas. Granular compounds will stand up to one or two waterings, giving greater control under these wet conditions. Liquid pesticides will be washed out immediately and little or no control is obtained.

The most important thing to remember, with sowbugs in particular, is that they generally will not occur on projects with virgin soils, that is, newly graded, uncultivated areas. Unless of course, there are surrounding areas with cover to harbor the pests. The problem generally occurs with renovations of older, established sites that have had existing growth for some time. The solution is recognizing the potential problem and then follow steps needed to eradicate the pest. Simply recognizing the problem is half the battle. Preventative preparation saves time and money for those costly call backs.