SPAN-WORMS. 



SPEARMINT. 



the trunks to go into the ground will be caught 

 and killed. If greater pains were to be taken 

 to destroy the insects in the caterpillar state, 

 their numbers would soon greatly diminish. 



Even after they have left the trees, have 

 gone into the ground, and have changed their 

 forms, they are not wholly beyond the reach of 

 means for destroying them. One person told 

 me that his swine, which he was in the habit 

 of turning into his orchard in the autumn, 

 rooted up and killed great numbers of the chry- 

 salids of the canker-worms. Some persons 

 have recommended digging or ploughing under 

 the trees, in the autumn, with the hope of 

 crushing some of the chrysalids by so doing, 

 and of exposing others to perish with the cold 

 of the following winter. If hogs are then al- 

 lowed to go among the trees, and a few grains 

 of corn are scattered on the loosened soil, these 

 animals will eat many of the chrysalids as 

 well as the corn, and will crush others with 

 their feet. Mr. S. P. Fowler thinks it better to 

 dig around the trees in July, while the shells 

 of the insects are soft and tender. He and 

 Mr. John Kenrick, of Newton, Mass., advise us 

 to remove the soil to the distance of 4 or 5 feet 

 from the trunk of the trees, and to the depth of 

 6 inches, to cart it away and replace it with an 

 equal quantity of compost or rich earth. In 

 this way, many of the insects will be removed 

 also ; but, unless the earth, thus carried away, 

 is thrown into some pond-hole, and left covered 

 with water, many of the insects contained in 

 it will undergo their transformations and come 

 out alive the next year. (See Yankee Farmer, 

 of July 19, 1840, and New England Farmer of 

 June 2, 1841, for some valuable remarks by 

 Mr. Fowler.) 



Canker-worms are subject to the attacks of 

 many enemies. Great numbers of them are 

 devoured by several kinds of birds, which live 

 almost entirely upon them during their season. 

 They are also eaten by a very large and splen- 

 did ground-beetle (Calosoma scrutator), that ap- 

 pears about the time when these insects begin 

 to leave the trees. These beetles do not ily, 

 but they run about in the grass after the canker- 

 worms, and even mount upon the trunks of the 

 trees to seize them a? they come down. The 

 latter are also stung by a four-winged ichneu- 

 mon-fly, which deposits an egg in every can- 

 ker-worm thus wounded. From the egg is 

 hatched a little maggot, that preys on the fatty 

 substance of the canker-worm, and weakens it 

 so much that it is unable to go through its fu- 

 ture transformations. I have seen one of these 

 flies sting several canker-worms in succession, 

 and swarms of them may be observed around 

 the trees as long as the canker-worms remain. 

 Their services, therefore, are doubtless very 

 considerable. Among a large number of can- 

 ker-worms, taken promiscuously from various 

 trees, I found that nearly one-third of the whole 

 were unable to finish their transformations, be- 

 cause they had been attacked by internal ene- 

 mies of another kind. These were little mag- 

 gots, that lived singly within the bodies of the 

 canker-worms, till the latter died from weak- 

 ness; after which the maggots underwent a 

 change, and finally came out of the bodies of 

 their victims in the form of small two-winged 

 1006 



cuckoo-flies, belonging to the genus Tachina, 

 Mr. E. C. Herrick, of New Haven, Connecticut, 

 has made the interesting discovery that the 

 eggs of the canker-worm moth are pierced by 

 a tiny four-winged fly, a species of Platygastcr, 

 which goes from egg to egg, and drops in each 

 of them one of her own eggs. Sometimes 

 every canker-worm egg in a cluster will be 

 found to have been thus punctured and seeded 

 for a future harvest of the -Platygaster. The 

 young of this Platygaster is an exceedingly mi- 

 nute maggot, hatched within the canker-worm 

 egg, the shell of which, though only one-thir- 

 tieth of an inch long, serves for its habitation, 

 and the contents for its food, till it is fully 

 grown; after which it becomes a chrysalis 

 within the same shell, and in due time comes 

 out a Platygaster fly, like its parent. This last 

 transformation Mr. Herrick found to take place 

 towards the end of June, from eggs laid in No- 

 vember of the year before ; and he thinks that 

 the flies continue alive through the summer, 

 till the appearance of the canker-worm moths 

 in the autumn affords them the opportunity of 

 laying their eggs for another brood. As these 

 little parasites prevent the hatching of the eggs 

 wherein they are bred, and as they seem to be 

 very abundant, they must be of great use in 

 preventing the increase of the canker-worm. 

 Without doubt, such wisely appointed means 

 as these were once enough to keep within due 

 bounds these noxious insects; but, since our 

 forests, their natural food, and our birds, their 

 greatest enemies, have disappeared before the 

 woodman's axe and the sportsman's gun, we 

 are left to our own ingenuity, perseverance, 

 and united efforts, to contrive and carry into 

 effect other means for checking their ravages. 



Apple, elm, and lime trees are sometimes 

 injured a good deal by another kind of span- 

 worm, larger than the canker-worm, and very 

 different from it in appearance. 



Probably more than one hundred different 

 kinds of geometers may be found in Massa- 

 chusetts alone. Seventy-eight are already 

 known to me. Some of these are small, and 

 are not otherwise remarkable ; some are dis- 

 tinguished for their greater size and beauty in 

 the moth state, or for the singularity of the 

 forms and habits of their caterpillars. None 

 of them, however, have become so notorious oa 

 account of their devastations as the species 

 already described. (Harris's Treatise.) See 

 LIMK TREE, INSECT ENEMIES. 



SPATTLING POPPY. A name sometimes 

 applied to chickweed. 



SPAVIN. In farriery, a disease in horses, 

 consisting of a swelling in or near some of the 

 joints, by which a lameness is produced, and 

 of which there are three kinds ; the blood-spavin, 

 the bog-spavin, and the bone-spavin. 



SPAYING. The operation of castrating or 

 extracting the ovaries of the females of different 

 kinds of animals, as sows, heifers, mares, &c., 

 in order to prevent any future conception, and 

 promote their fattening. 



SPEAR GRASS. The American name for 

 the great smooth-stalked meadow-grass. See 



POA PRATEXSIS. 



SPEARMINT (Mentha viridis). This species 

 of mint is employed in sauces and salads, as 



