Economic entomology for the farmer Economic entomology for the farmer and the fruit grower, and for use as a text-book in agricultural schools and colleges; economicentomol00smit Year: 1906 344 AiV ECONOMIC ENTOMOLOGY. Fig. 393. An Asilid fly.—Erax bastardi larva, pupa, and adult. their resemblance to, and to distinguish them from, the ' horse- flies.' Another series of large species we find among the 'robber- flies' belonging to the family Asilidcz, and these are quite different in appearance from any heretofore treated. The head is prominent, very hairy, with rather short, several-jointed
Economic entomology for the farmer Economic entomology for the farmer and the fruit grower, and for use as a text-book in agricultural schools and colleges; economicentomol00smit Year: 1906 344 AiV ECONOMIC ENTOMOLOGY. Fig. 393. An Asilid fly.—Erax bastardi larva, pupa, and adult. their resemblance to, and to distinguish them from, the ' horse- flies.' Another series of large species we find among the 'robber- flies' belonging to the family Asilidcz, and these are quite different in appearance from any heretofore treated. The head is prominent, very hairy, with rather short, several-jointed antennae, and with a short, stout proboscis, which is formed for piercing. The body is robust, also covered with hair, and the abdomen is long, slender, and cylindrical, tapering very gradually to the tip. The wings are long and nar- row, the legs moderately long and very powerful, densely clothed with spines, while the tips of the tarsi are supplied with unusually long and stout claws. The insects are called '' robber-flies'' from their habit of pouncing upon, piercing, and sucking the juices of other insects in mid-air, while holding them with their powerful legs. We have a great variety of species, some of them large and brightly colored, though the majority are of a sober gray, varying sometimes to reddish, sometimes to yellow, and only rarely becoming black, except in the genus Laphria. Though predaceous, the insects can hardly be called beneficial, because they rarely attack injurious species, and in some cases become themselves injurious by attacking bees. The late Dr. C. V. Riley records having observed a single species kill forty bees in one afternoon. Professor Comstock notes their feeding upon the cotton-worm, and undoubtedly they do occasionally kill injurious insects, but can scarcely be credited with being a factor of much importance in keeping down troublesome forms. They never attack man or animals, although, if carelessly handled, they are ready to sink thei
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