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Ogilvy et al. 2012). However, the results can be inconsistent, due to a variety of factors that impact
how much of the diet and the supplemental nutrient in question is actually consumed by the insect
(Finke 2003; Livingston et al. 2014). This inconsistency was demonstrated by the fact that only one
of seven commercially-available gut-loading products sold in pet stores significantly increased
cricket calcium content above that of the control group (Finke et al. 2004, 2005). Further, gut-
loading foods are not suitable maintenance diets and may negatively impact viability when used
for more than a few days (e.g. Klasing et al. 2000). This means that a rehabilitation facility would
have to keep two colonies of each insect species used, one on a maintenance diet and another on
the gut-loading diet. A comprehensive review of these issues may be found in Livingston et al.
(2014), and although this article focused on crickets, the issues are similar regarding other species
of insects. In summary, care is required in selecting and implementing gut-loading diets, especially
those that are not supported by published research.
Dusting is another method used to supplement feeder insects (Figure 41.3). This approach
involves using a fine powder, typically calcium carbonate with or without other nutrients, and
applying it to the insect just prior to offering it as food. Dusting can be an effective means of sup-
plementation, but the amount that adheres to the insect depends on factors that include the char-
acteristics of the powder, the species and age/size of the insect, and the ability of that insect to
remove the powder by grooming over time since the dust was applied (Winn et al. 2003; Michaels
et al. 2014). The previously-mentioned review by Livingston et al. (2014) also contains a discussion
and summary of research on dusting crickets. While dusting can be effective, care must be taken,
as the results can be inconsistent.
Another strategy is delivering supplements in oily pastes that can be applied to insects in greater
quantities than would be possible with powders. For nestling and fledgling passerines raised on
100% insects, Perlman (2016) suggested creating a package of human supplements comprising
calcium, vitamins A, C, D, and E, plus taurine and omega-3 marine oil. The supplement mix is
either applied daily to a feeder insect or fed directly in small amounts that vary according to
the size of the bird. Because the supplements are packaged for human consumption, users must
estimate small fractions of a total mixture volume, which may affect accuracy. Also, without

Figure­41.3­ Eastern Phoebe fed calcium-dusted mealworm. Source: photo courtesy of Diane Winn/Avian
Haven.