INSECTS AFFECTING PARK AND WOODLAND TREES l6l 



Grand Surprise are worthy of mention. The injurious caterpillar could 

 easily be designated as the larva of the mourning cloak or whatever com- 

 mon name is preferred, but it is simpler for a person interested only in the 

 practical side of the subject to use a special name for the caterpillar and 

 therefore, following Dr C. M. Weed, we have employed the designation of 

 spiny elm caterpillar for this destructive larva. 



Food plants. This insect is more frequently brought to notice on 

 account of its depredations on the white or American elm, though it is also 

 very injurious to willows and poplars but the small value of the latter two 

 renders the damage of less importance. The caterpillars are also recorded 

 as feeding on the hackberry, C e 1 1 i s o c c i d e n t a 1 i s, and the butterfly 

 has been observed depositing its eggs on white and canoe birch. 



Distribution. Mr Scudder in his work. The Duttcrjlics of N^cw England, 

 writes that this insect " is apparently distributed over the entire breadth of 

 the northern hemisphere below the Arctic circle as far as the thirtieth 

 parallel of latitude." He further states that it is found in nearl_\' equal 

 abundance throughout New England and flies to but does not breed on the 

 highest summits of the White mountains. 



Natural enemies. There are several insects which prey on this species. 

 A minute, four winged fly known as Telenomus graptae How. 

 ■watches its opportunity to oviposit in the eggs of this butterfly. P t e r o- 

 malus fuscipes Prov., was reared in Albany last summer from this 

 insect. Three other Chalcids, Pteromalus vanessae How., P t e r o- 

 m a 1 u s p u p a r u m Linn, and PL n t e d o n a n t i o p a e Pack., all minute, 

 four winged flies, attack the caterpillars, the former two sometimes in 

 large numbers. Several ichneumon ilies are parasitic on this species in 

 Europe but no records of such rearings in America have been found. A 

 dipterous parasite, P3 u p h o r o c e r a c 1 a r i p c n n i s Macq,, has been reared 

 in this country from the caterpillars. A fierce ground beetle, C al o s o m a 

 scrutator Pabr., is another enemy. This beneficial species is com- 

 parativel)' rare however. Two predaceous bugs. Pod is us placidus 

 Uhler and P. serieventris Uhler, prey on the caterpillars as recorded 



