HOT-HOUSE THRIPS. 263 



winged like the males, and other structural characters. Next 

 above stands Coccus, which resembles, in the adult stage of the 

 female, the young of Lecanium and Aspidiotus. The genus 

 Lecanium differs, besides other structural characters in tlie fe- 

 males remaining very minute, and secreting a scalelike covering, 

 or cocoon, which, as in A. conchiformis or A. Gloverii, is long 

 and narrow, with the dead skin of the female at the smaller end, 

 or surrounded by it wholly, as in A. bromelice. In Lecanium, 

 however, the female grows to a large size before laying her eggs, 

 which are not protected by a scale, but by a cottony secretion. 

 I have found the young of L. platycerii hiding under the body 

 of their parent, which was still living, moving its antennae and 

 legs. The Aspidiotus should therefore be considered, perhaps, 

 as a step higher than Lecanium in the zoological scale. 



Tlie Hot-House Thrips. — (PI. 1, fig. 2, magnified.) This is 

 one of the greatest pests in our hot-houses. It is the Helio- 

 thrips hcemorrhoidalis of Burmeister, and agrees perfectly with 

 the descriptions of the European insect. In all its stages it 

 may be found puncturing the leaves of liliaceous plants, azalia, 

 Pellea hastata, aspidium, pinks, &c., &c., and by its attacks caus- 

 ing the surface of the leaf to turn red or white in blotches, or 

 sometimes the whole leaf withers and whitens. The larva and 

 pupa are white, long, with short antennse. After several suc- 

 cessive changes, it assumes the adult state, and the pupee may 

 be found in different stages of growth, with the antennse turned 

 imderneath the head, and the rudimentary wings folded to 

 the sides of the body. The eyes are pink. The half-grown 

 young are shorter and broader than those fully mature. Hali- 

 day describes the adult in the following words : " Dusky black, 

 the extremity of the abdomen ferruginous. Antennae and legs 

 white, the base and sixth joint of the former dusky, wings 

 almost hyaline. The body above is entirely netted with elevated 

 lines, forming pretty regular hexagons, equal in size on the head, 

 where they are largest, to those of the eyes, and disposed in 

 perfect rows on the abdomen." It is about one-twelfth of an 

 inch in length. 



The best remedy against them is repeated washings with soap- 

 suds, cleaning each leaf by itself. 



Peabodt Academy of Science, 

 Salem, February 10, 1870. 



