Cryptic species are present in many animal groups and they may be best detected through large sample sizes collected over broad geographic ranges. Fine-scale local adaptation has been hypothesized to occur in armoured scale insects (Hemiptera: Diaspididae) and a consequence of this process may be multiple cryptic species. We estimate species diversity of pine-feeding Chionaspis scale insects across North America by inferring species boundaries using genealogical concordance across allele genealogies of two nuclear loci and one mitochondrial locus. Our ingroup sample includes 366 individual insects from 320 localities and 51 host species within the Pinaceae. We also conducted a morphological survey of all insect specimens and assigned them as either one of the two currently recognized pine-feeding species, Ch. heterophyllae, Ch. Pinifoliae, or with undescribed morphology. Using maximum likelihood allele genealogies in a majority-rule consensus to assess congruence, we conservatively detect ten species in this group. Most of these species are robust to alternative methods of genealogical inference (Bayesian inference, maximum parsimony) and a few are robust to the use of strict consensus to assess congruence. Species show both narrow and more widespread ranges where almost half of the individuals sampled belong to a single very widespread polyphagous species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 47–62.