| Species | Sites Reporting | Year |
|---|---|---|
| Cabbage White | 58 | 1999 |
| Monarch | 58 | 1999 |
| Common/Orange Sulphur | 57 | 1999 |
| Pearl Crescent | 54 | 1999 |
| Black Swallowtail | 52 | 1999 |
| Eastern Tiger Swallowtail | 49 | 1999 |
| Great Spangled Fritillary | 45 | 1999 |
| Spring/Summer Azure | 44 | 1999 |
| Eastern Tailed Blue | 44 | 1999 |
| Buckeye | 40 | 1999 |
| Red Admiral | 38 | 1999 |
| Silver Spotted Skipper | 35 | 1999 |
| Common Wood Nymph | 31 | 1999 |
| Viceroy | 31 | 1999 |
| European Skipper | 29 | 1999 |
| Little Wood Satyr | 27 | 1999 |
| Question Mark | 27 | 1999 |
| Mourning Cloak | 23 | 1999 |
| Least Skipper | 22 | 1999 |
| Fiery Skipper | 22 | 1999 |
| Eastern Comma | 22 | 1999 |
| Eyed Brown | 20 | 1999 |
| Peck's Skipper | 19 | 1999 |
| Red-Spotted Purple | 19 | 1999 |
| Tawny Edge | 18 | 1999 |
| Delaware Skipper | 16 | 1999 |
| Silvery Checkerspot | 15 | 1999 |
| Northern Pearly-eye | 14 | 1999 |
| Snout Butterfly | 13 | 1999 |
| Banded Hairstreak | 11 | 1999 |
| Black Dash | 10 | 1999 |
| Bronze Copper | 10 | 1999 |
| Coral Hairstreak | 9 | 1999 |
| Little Yellow | 9 | 1999 |
| Dun Skipper | 9 | 1999 |
| Spicebush Swallowtail | 8 | 1999 |
| Appalachian Brown | 8 | 1999 |
| American Painted Lady | 8 | 1999 |
| Pipevine Swallowtail | 7 | 1999 |
| Gray Hairstreak | 6 | 1999 |
| Common Sootywing | 6 | 1999 |
| Dion Skipper | 6 | 1999 |
| Hobomok Skipper | 6 | 1999 |
| Horace's Duskywing | 6 | 1999 |
| Broken Dash | 6 | 1999 |
| Aphrodite | 5 | 1999 |
| Wild Indigo Duskywing | 5 | 1999 |
| Acadian Hairstreak | 5 | 1999 |
| Hackberry Butterfly | 5 | 1999 |
| Giant Swallowtail | 5 | 1999 |
| Cloudless Sulphur | 4 | 1999 |
| Meadow Fritillary | 4 | 1999 |
| Mulberrywing | 4 | 1999 |
| Olympia Marble | 3 | 1999 |
| Baltimore Checkerspot | 3 | 1999 |
| Edwards Hairstreak | 3 | 1999 |
| Variegated Fritillary | 3 | 1999 |
| Crossline Skipper | 3 | 1999 |
| Broadwinged Skipper | 3 | 1999 |
| Striped Hairstreak | 3 | 1999 |
| Juvenal's Duskywing | 2 | 1999 |
| Zabulon Skipper | 2 | 1999 |
| Little Glassywing | 2 | 1999 |
| American Copper | 2 | 1999 |
| Harvester | 2 | 1999 |
| Regal Fritillary | 2 | 1999 |
| Long Dash | 2 | 1999 |
| Two Spot Skipper | 2 | 1999 |
| Sachem | 2 | 1999 |
| Checkered Skipper | 2 | 1999 |
| Hoary Elfin | 2 | 1999 |
| Tawny Emperor | 2 | 1999 |
| Dogface | 1 | 1999 |
| Purplish Copper | 1 | 1999 |
| Sleepy Duskywing | 1 | 1999 |
| Dwarf Sulphur | 1 | 1999 |
| Goatweed Butterfly | 1 | 1999 |
| Gray Comma | 1 | 1999 |
| Milbert's Tortoiseshell | 1 | 1999 |
| Silver-Bordered Fritillary | 1 | 1999 |
| Dusky Azure | 1 | 1999 |
| Olive Hairstreak | 1 | 1999 |
| Leonard's Skipper | 1 | 1999 |
| Zebra Swallowtail | 1 | 1999 |
| White-M Hairstreak | 1 | 1999 |
| Northern Cloudywing | 1 | 1999 |
Illinois Butterfly Monitoring Network
The Illinois Butterfly Monitoring Network engages citizen scientists in the process of collecting quantitative data on butterfly populations.