Tarsocera cassus

{{Short description|Species of butterfly}}

{{Speciesbox

| name = Spring widow

| image = Tarsocera cassus.jpg

| taxon = Tarsocera cassus

| authority = (Linnaeus, 1764)[http://www.nic.funet.fi/pub/sci/bio/life/insecta/lepidoptera/ditrysia/papilionoidea/nymphalidae/satyrinae/tarsocera/index.html Tarsocera] at Markku Savela's Lepidoptera and Some Other Life Forms

| synonyms =

• Papilio cassus Linnaeus, 1764
• Dira cassus (Linnaeus, 1764)

}}

Tarsocera cassus, the spring widow, is a butterfly of the family Nymphalidae. It is found in South Africa.

The wingspan is 42–52 mm for males and 50–57 mm for females. Adults are on wing from September to December (with a peak in October or November). There is one generation per year{{cite book|last=Woodhall |first=Steve |title=Field Guide to Butterflies of South Africa |year=2005 |location=Cape Town, South Africa |publisher=Struik |isbn=978-1-86872-724-7 }}

The larvae feed on various Poaceae species, including Lolium temulentum and Haparrhenia hirta.