PHORA ALETIAE. 209 



alive or appeared parasitized, we may consider this as good proof of the 

 true parasitic habits of the species. 



With the determination of the species as belonging to the genus 

 PJwra, however, all doubt as to its parasitic habits was lost, as many 

 species of the genus are known to be parasitic upon other insects. The 

 most celebrated species, perhaps, is P. incrassata of Europe, concerning 

 the habits of which we quote the following from an article by Dr. Pack- 

 ard in the American Naturalist for 1868 : 



An insect allied to the Tachina has been found in Europe to be the most formidable 

 foe of the hive-bee, sometimes producing the well-known disease called "foul-brood," 

 which is analogous to the typhus fever of man. 



This fly, belonging to the genus Phora, is a small insect about one line and half 

 long, and found in Europe during the summer and autumn, flying slowly about flow- 

 ers and windows and in the vicinity of bee-hives. Its white, transparent larva is cylin- 

 drical, a little pointed before, but broader behind. The head is small and rounded with 

 short three-jointed anntenre, and at the posterior end of the body are several slender 

 spines. The puparium, or pupa-case, inclosing the delicate chrysalis, is oval, consist- 

 ing of eight segments, flattened above, and with two large spines near the head and 

 four on the extremity of the body. 



When impelled by instinct to provide for the continuance of its species, the Phora 

 enters the bee-hive and gains admission to a cell, when it bores with its ovipositor 

 through the skin of the bee larva, laying its long oval egg in a horizontal position 

 just under the skin. The embryo of the Phora is already well developed, so that in 

 three hours after the egg is inserted in the body of its unsuspecting and helpless host 

 the embryo is nearly ready to hatch. In about two hours more it actually breaks off 

 the larger end of the egg-shell, and at once begins to eat the fatty tissues of its victim, 

 its posterior half still remaining in the shell. In an hour more it leaves the egg 

 entirely and buries itself completely in the fatty portion of the young bee. 



The maggot moults three times. In twelve hours after the last molt it turns 

 around with its head toward the posterior end of the body of its host, and in another 

 twelve hours, having become full-fed, it bores through the skin of the young, eats its 

 way through the broad covering of the cell, and falls to the bottom of the hive, when 

 it changes to a pupa in the dust and dirt, or else it creeps out of the door and trans- 

 forms in the earth. Twelve days after the fly appears. 



The young bee, emaciated and enfeebled by the attacks of its ravenous parasite, 

 dies, and its decaying body fills the bottom of the cell with a slimy foul-smelling 

 mass, called "foul-brood." This gives rise to a miasma which poisons the neighbor- 

 ing brood, until the contagion (for the disease is analogous to typhus, jail, or ship 

 fever) spreads through the whole hive, unless promptly checked by removing the 

 cause and thoroughly cleansing the hive. 



Foul-brood sometimes attacks our American hives, and, though the cause may not 

 be known, yet from the hints given above we hope to have the history of our suecies 

 of Phora cleared up, should our disease be found to be sometimes due to the attacks of 

 such a parasite fly. 



Mr. Edward Burgess informs me, after comparing specimens of the 

 Phora bred from Aletia with the types in the Cambridge collection, that 

 this is probably a new species. I will therefore provisionally designate 

 it as Phora aletiae, and submit the following description to* accompany 

 the figures : 

 PHOIIA ALETIAE, n. sp. 



LARVA. Length of mature larva about 3.6 mm . ; tapers gradually from the 9th seg- 

 ment towards the head; color milk-white; body very much wrinkled, the wholo 

 surface sparsely beset with short, backward-directed teeth, which arft most conspic- 

 14 c I 



