INSECTS IN THE PLANT-HOUSE. 257 



The thorax is cylindrical and very long, being nearly half as 

 long as the abdomen, and very smooth. On the prothoracic seg- 

 ment is a large, long, narrow, curved spiracle, while the abdom- 

 inal spiracles, seven on each side of the body, are round and 

 raised on a low tubercle. 



The abdomen is long, cylindrical ; the segments are not con- 

 vex, and the sutures between them are well defined. On the 

 posterior edge of each segment is a row of stiff hairs surround- 

 ing the body ; they are not so stiff and spinelike as in the Asilidas. 

 On the tip, which is rather blunt, are six short, stout spines. 

 The legs and wings are soldered to the body more closely than 

 in the pupee of the Asilidee, and are merged with the integument. 

 When the fly emerges from the chrysalis, the thorax splits open 

 along the back, the front of the head separates, falls forwards, 

 and the fly crawls out of the rent thus formed. 



This species is larger than most of the species of Tabanus, 

 and seems to differ generically from them in the conical head, 

 the large eyes, while the mouth-parts are constructed more like 

 those of the common house-fly, the bladelike jaws and labrum 

 not being well developed, so that it is doubtful whether this 

 species bites like the well-known " green-head " horse-fly and 

 its allies. This species is nearly an inch in length, and is black 

 throughout, including the mouth-parts, legs, antennae and wings. 



PLANT-HOUSE INSECTS. 



By far the most injurious insect in our plant-houses is the 

 Aphis, of which I have noticed two species which have probably 

 been imported from Europe. One is entirely green, with a 

 broad, flattened abdomen. The wingless, asexual form, is fig- 

 ured on PL 1, fig. 1. I have not yet been able to identify the 

 species. The other is spotted with black on the abdomen, and 

 is abundant on various hot-house plants. The best means to 

 get rid of them is to smoke the plants with tobacco, or wash 

 them with soap-suds, and turn a stream on them from a hose. 



The White Scale Bark-Louse. — The most troublesome bark- 

 louse in the Amherst and Cambridge plant-houses is the Aspi- 

 dioius bromeliae of Bouch^. (PI. 1, fig. 6, magnified ; 4, young, 

 magnified ; 4a, end of body still more enlarged.) It infests the 

 long, narrow leaves of the acacia, the small, white scales crowd- 

 ing upon one another, especially along the mid rib, scarcely a 



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