The following butterfly species (those in bold) were seen in Berks County, Pennsylvania in 2004. There have been records of 106 species seen in Berks County. The list below includes all those reported in 2003 and 2004, a total of 73 species. No doubt other species were present, but not seen. Some of the 106 species are historical records and many are of strays or southern migrants which are not often found in the county. Ninety one of the 106 species are known to have been seen in the past 40 years. The most notable sightings this year were those of the Sleepy Orange, Zebra Swallowtail, Gray Comma and, Red-banded Hairstreak. The first two had not been recorded in decades. Since 1997 the following six species have been added to the Berks County list: Sachem (a skipper), Broad-winged Skipper, Horace's Duskywing (a skipper), Ocola Skipper, Gray Comma, and Red-banded Hairstreak.

Sightings in 2004    (63 species)  (63 species were also seen in 2003.) A total of 73 species have been seen in the two years.

 Family HESPERIIDAE
1 Silver-spotted Skipper
2 Northern Cloudywing
3 Dreamy Duskywing
4 Sleepy Duskywing
5 Juvenal's Duskywing
6 Horace's Duskywing
7 Wild Indigo Duskywing
8 Checkered Skipper
9 Common Sootywing
10 Swarthy Skippper
11 Least Skipper
12 European Skipper
13 Fiery Skipper
14 Leonard's Skipper
15 Cobweb Skipper
16 Indian Skipper
17 Peck's Skipper
18 Tawny-edged Skipper
19 Crossline Skipper
20 Long Dash
21 Northern  Broken Dash
22 Little Glassy Wing
23 Sachem
24 Delaware Skipper
25 Hobomok Skipper
26 Zabulon Skipper
27 Broad-winged Skipper
28 Dun Skipper
29 Ocola Skipper
 Family PAPILIONIDAE
30 Pipevine Swallowtail
31 Zebra Swallowtail (First sighting in many years.)
32 Black Swallowtail
33 Tiger Swallowtail
34 Spicebush Swallowtail
35 Giant Swallowtail 
 Family PIERIDAE 
36 Cabbage Butterfly
37 Clouded Sulphur
38 Orange Sulphur
39 Sleepy Orange  (First sighting in many years.)