. Economic entomology for the farmer and fruit-grower. Beneficial insects. 374 AN ECONOMIC On grapes there are often black-dotted slugs, the larvae of Blennocampapygmaa, that do some injury ; and on roses almost every grower has been annoyed by numer- â ^^^' ous green slugs, the larvae of Monostegia }'0S(e, which make their appearance early in the season. Raspberries are sometimes severely in- jured by little spiny slugs, the larvae of Monophadnus rubi, that appear in June or early July, first eating round holes in the leaves, but eventually, when they become Grape-slug, larva of
. Economic entomology for the farmer and fruit-grower. Beneficial insects. 374 AN ECONOMIC On grapes there are often black-dotted slugs, the larvae of Blennocampapygmaa, that do some injury ; and on roses almost every grower has been annoyed by numer- â ^^^' ous green slugs, the larvae of Monostegia }'0S(e, which make their appearance early in the season. Raspberries are sometimes severely in- jured by little spiny slugs, the larvae of Monophadnus rubi, that appear in June or early July, first eating round holes in the leaves, but eventually, when they become Grape-slug, larva of ^/('«- numcrous euough, taking the foliage com- nocampa pygmtra. pletely. Many other cultivated plants, m- cluding the strawberry, are attacked by these saw-fly larvae ; but their habits are very similar, and the remedies to be adopted against them are also very much the same. The largest of our American species, Cimbex americana, is found on willow, sometimes in considerable number, as a pow- dery, whitish larva an inch and a half in length, with a broad dark stripe on its back. Experience has shown that all these species are very suscep- tible to the influence of white hellebore, and that even a small quantity is quickly fatal. Infested plants can, therefore, be cleared in a few hours by a thorough drenching with a decoction of white hellebore, used at the rate of one ounce in one gallon of water ; or the plants may be dusted with the powder, undiluted or mixed with several times its own bulk of cheap flour. Any stomach poisonâ, the arsenites or tobaccoâwill answer as well as hellebore, while on the slimy types even fine road-dust will quickly choke them to death. Air-slaked or dry hydrate of lime burns through them in less than an hour when carefully ap- plied. These insects are so easily killed that it is the fault of the farmer himself if he suffers injury. The "horn-tails" resemble the "saw-flies" in away, but the character of the ovipositor
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