<p> Table S6 Total number of base pairs found at the interface regions between double-stranded and single-stranded regions (junctions, bulges and internal and terminal loops). Two base pairs at the vicinity of these regions were considered. The observed and expected values of GC, GU and</p><p>AU pairs at these regions are shown, including the results of a chi-square test comparing them. GU and AU pairs were grouped together since both are less stable than GC pairs and because UG ↔ UA and GU ↔ AU are the most common hemi-CBCs found in this dataset (Table S9). Bold numbers indicate significant results at p<0.05 (**) and p<0.10 (*)</p><p>Total pairs at Total pairs (observed) Total pairs (expected) chi-square Species interface regions GC GU AU GU+AU GC GU AU GU+AU GC GU+AU Total p-value(1d.f.) Calliphora vomitoria 62 17 0 45 45 10.3333 4.01852 47.6481 51.6667 4.30108 0.86022 5.16129 p<0.025 ** Aldrichina grahami 75 19 4 52 56 13.8889 4.86111 56.25 61.1111 1.88089 0.42747 2.30836 p<0.15 Calliphora vicina 68 15 5 48 53 9.44444 6.2963 52.2593 58.5556 3.26797 0.52709 3.79507 p<0.06 * Lucilia caesar 73 16 3 54 57 11.4907 4.73148 56.7778 61.5093 1.76955 0.33057 2.10012 p<0.15 Lucilia illustris 68 16 3 49 52 10.5631 5.28155 52.1553 57.4369 2.7984 0.51465 3.31305 p<0.07 * Hemipyrellia ligurriens 70 15 3 52 55 10.6061 3.53535 55.8586 59.3939 1.82035 0.32506 2.14541 p<0.15 Lucilia cuprina 66 17 1 48 49 12.1224 2.02041 51.8571 53.8776 1.96252 0.44157 2.40408 p<0.15 Lucilia sericata 66 17 3 46 49 11.88 3.96 50.16 54.12 2.2066 0.48438 2.69097 p<0.15 Lucilia ampullacea 62 16 3 43 46 11.0222 2.75556 48.2222 50.9778 2.24803 0.48606 2.73409 p<0.10 * Lucilia porphyrina 66 17 1 48 49 11.9362 2.10638 51.9574 54.0638 2.14829 0.4743 2.62259 p<0.15 Lucilia bazini 54 15 1 38 39 9.81818 3.68182 40.5 44.1818 2.73485 0.60774 3.34259 p<0.07 * Lucilia eximia 73 17 0 56 56 11.3853 3.34862 58.2661 61.6147 2.76888 0.51164 3.28052 p<0.07 * Chrysomya megacephala 62 15 6 41 47 10.1346 6.55769 45.3077 51.8654 2.33575 0.45641 2.79217 p<0.10 * Chrysomya bezziana 62 15 4 43 47 10.233 6.01942 45.7476 51.767 2.22068 0.43897 2.65965 p<0.15 Chrysomya saffranea 62 15 5 42 47 9.9434 6.43396 45.6226 52.0566 2.57148 0.49118 3.06266 p<0.08 * Chrysomya pinguis 58 15 3 40 43 9.57282 5.63107 42.7961 48.4272 3.07687 0.60822 3.68509 p<0.06 * Chrysomya latifrons 55 16 5 34 39 9.33962 7.26415 38.3962 45.6604 4.74972 0.97153 5.72126 p<0.025 ** Chrysomya semimetallica 59 16 6 37 43 9.28704 8.19444 41.5185 49.713 4.85234 0.90648 5.75882 p<0.025 ** Chrysomya albiceps 68 16 1 51 52 11.027 3.06306 53.9099 56.973 2.24271 0.43407 2.67679 p<0.15 Chrysomya rufifacies 69 16 4 49 53 11.5 4.47222 53.0278 57.5 1.76087 0.35217 2.11304 p<0.15 Chrysomya incisularis 75 17 1 57 58 11.9469 3.9823 59.0708 63.0531 2.13727 0.40496 2.54223 p<0.15 Chrysomya nigripes 70 14 7 49 56 10.8182 8.27273 50.9091 59.1818 0.93583 0.17107 1.10689 p<0.30 Chrysomya putoria 71 17 4 50 54 12.5294 4.87255 53.598 58.4706 1.59514 0.34182 1.93696 p<0.20 Chrysomya flavifrons 63 16 2 45 47 9.82569 4.62385 48.5505 53.1743 3.87984 0.71693 4.59677 p<0.03 ** Chrysomya varipes 61 16 3 42 45 9.97115 5.27885 45.75 51.0288 3.64521 0.71228 4.3575 p<0.04 ** Cochliomyia hominivorax 66 15 2 49 51 9.58065 4.79032 51.629 56.4194 3.06549 0.52056 3.58605 p<0.06 * Cochliomyia macellaria 65 13 2 50 52 8.84 5.2 50.96 56.16 1.95765 0.30815 2.2658 p<0.15 Hemilucilia segmentaria 66 15 2 49 51 10.0179 4.71429 51.2679 55.9821 2.47775 0.44339 2.92114 p<0.09 * Chloroprocta idioidea 69 15 3 51 54 10.7615 3.16514 55.0734 58.2385 1.6694 0.30848 1.97787 p<0.20 Phormia regina 65 16 4 45 49 9.20354 5.75221 50.0442 55.7965 5.01892 0.82786 5.84679 p<0.02 ** Protophormia terraenovae 68 15 2 51 53 10.0741 3.77778 54.1481 57.9259 2.40863 0.41889 2.82753 p<0.10 * Mesembrinella peregrina 69 17 0 52 52 12.3474 2.90526 53.7474 56.6526 1.75317 0.3821 2.13527 p<0.15 Mesembrinella bellardiana I 72 17 5 50 55 16 4.66667 51.3333 56 0.0625 0.01786 0.08036 p<0.80 Mesembrinella bellardiana II 67 16 5 46 51 13.5354 4.06061 49.404 53.4646 0.44879 0.11362 0.5624 p<0.50 Stomoxys calcitrans 59 13 9 37 46 11.0625 6.14583 41.7917 47.9375 0.33934 0.07831 0.41764 p<0.60 Musca domestica 74 22 6 46 52 16.7304 5.7913 51.4783 57.2696 1.65975 0.48487 2.14462 p<0.15 Haematobia irritans 72 17 7 48 55 14.1308 8.07477 49.7944 57.8692 0.58256 0.14225 0.72481 p<0.40</p>