394 STATE HORTICULTURAL SOCIETY. 



the dark green background of the celery leaf an object that is readily seen. 

 It has been known as a celery caterpillar for some time. Every year we 

 receive specimens of the caterpillar with a great many queries regarding 

 it; not particularly because it is so plentiful, but because it so quickly 

 catches the attention and arouses the curiosity. The Y-shaped yellow 

 horns, that it throws out when annoyed, have no sting and are harmless. 

 They are scent organs that emit a very disagreeable odor as a protection 

 against its enemies, 



FROM CATERPILLAR TO BUTTERFLY. 



Of course, this caterpillar first hatched from an egg that was laid on the 

 celery plant. At first the caterpillar is small, but in only a few weeks it 

 has grown to its full size. Then it attaches itself to the stem and in a few 

 hours time the caterpillar will have become a chrysalis as seen at d, Plate 

 II. This is the resting period, as it has little power to move and eats noth- 

 ing; but on some bright sunny morning a fresh, new, black and yellow 

 butterfly comes from this pnpa case and spreads her gauzy wings ready for 

 flight. The butterfly feeds only on the sweets from flowers and does the 

 celery no harm, except that, after a few days of her career, she haunts the 

 celery field and deposits her eggs there for another brood. The cater- 

 pillars are the most common through September, but are occasionally seen 

 in July and August. They live through the winter in the chrysalis stage. 



OTHER FOOD PLANTS. 



Parsnip, carrot, and wild parsnip are fed upon by this caterpillar as 

 readily as celery. Many other plants as caraway, parsley, sweet fennel, 

 etc., belonging to the same family, also furnish it food. 



NUMBERS REDUCED BY A PARASITE. 



Whenever these caterpillars are present, 

 wasp-like parasites with yellowish red 

 bodies and black wings, may be seen dart- 

 ing through and around the plants in 

 search of their host. The young of these 

 parasites feed inside the caterpillars, and 

 f\P after the caterpillar has changed to a 

 * A l»i^ '^ chrysalis, the parasite gnaws a hole in the 

 X^ case and comes forth instead of a butter- 



* ' fly. The parasite (Trogus exessorius) 



Fig. u— Trogus e.ressoriMs on the pupa case helps greatly to keep the number of cater- 



from which it has issued at the side. Twice „'ii„ „ i^ ^^^A 



natural size (orignai). pillarS lessened. 



* 



REMEDIES. 



As a usual thing the caterpillars will not be plentiful enough to need 

 special attention. When so large and conspicuous, hand picking would be 

 a ready remedy. 



