Appreciation of virus-biofilm ecological interactions remains poorly developed. One conspicuously unanswered question is the extent to which naturally occurring biofilms are virus susceptible. As has been previously suggested, physical and genetic heterogeneity across both environments and individual biofilms could limit the productivity and therefore effectiveness of wild phages as biofilm-eradicating agents, even if individual biofilm bacteria are still highly permissive to phage infection (Abedon, 2011, monograph). Clonal clumps of bacteria making up biofilms, called microcolonies, nevertheless could be more susceptible to phage exploitation if they are either more numerous across environments or instead individually larger in size (Abedon, 2012, Viruses). Physiological heterogeneity across biofilms also has been considered by a number of researchers as a mechanism which could reduce biofilm vulnerability to phages without blocking all phage infections, such as if new biofilm growth is what is especially exploitable by phages (Abedon, FEMS Microbiology Letters, 2016). Combining models, it would be large, environmentally numerous microcolonies possessing substantial still-phage-vulnerable new bacterial growth which should be most likely to suffer extensive phage exploitation in the wild rather than biofilms in general displaying substantial or, alternatively, a complete lack of vulnerability to phages—e.g., just as tender leaves on more abundant plants can be especially susceptible to herbivory. The result is a non-strain-specific hypothesis for why biofilms in nature could give the impression of being phage resistant despite a well-documented potential for phages to eradicate biofilms in the laboratory. An example of partial biofilm susceptibility/resistance to phage-mediated eradication is likely seen during the phage therapy of biofilm-associated chronic bacterial infections. Better laboratory approximation of such interactions – particularly realistic conditions where phage-mediated eradication of biofilms is demonstrably challenging and thereby potentially experimentally informative – should help to increase our appreciation of phage-biofilm interactions in nature while also improving bacterial eradication strategies during anti-biofilm phage therapies.