Family: Chrysomelidae
Subfamily: Chrysomelinae
Length: 7-9 mm
We're picturing these two species on one page because they are easily confused with each other. The clearest difference is that Calligrapha multipunctata (left) has considerable white on the pronotum. Calligrapha philadelphica (below) has an all-dark pronotum.
Food plants will also distinguish the two species. Calligrapha multipunctata feeds on members of the Willow family, while Calligrapha philadelphica feed on Silky Dogwood and other Dogwoods.
Right: the all-dark pronotum distinguishes this species, Calligrapha philadelphica, from the similar species Calligrapha multipunctata.
Clark (2000) indicates that with Calligrapha philadelphica a majority of specimens were collected in May. Calligrapha multipunctata specimens were taken from April through September, with July being the peak month.
Robertson (1966) reported that in some populations of Calligrapha philadelphica the two sexes are present in approximately equal numbers, but that one collection site yielded 24 males and 35 females, and another 0 males and 12 females. In a combined sample from Ontario, there were 98 males and 152 females. In certain other species of Calligrapha males are unknown, and those species reproduce by parthenogenesis.
Robertson reported that most colonies of Calligrapha multipunctata had essentially equal numbers of males and females, but that one colony in Ottawa yielded 11 males and 24 females.
Calligrapha is a fascinating genus to use in studying the process of speciation. There are few discernible morphological differences between many species of Calligrapha, and the identity of the food plant can be a key identification characteristic. Although Calligrapha multipunctata and Calligrapha philadelphica look very much alike, these two species (with two different food plants) have not been observed mating. On the other hand, Calligrapha philadelphica has been observed to copulate with Calligrapha rowena; these two species share the same foodplant, Dogwood.
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