1920] Richmond, Studies on the Biology of the Aquatic Hydrophilidce 43 



Laccobius Erickson 



This genus is evidently represented by one species and a variety in 

 New York State but the variety has not been described to date. The 

 more common or silvery species is apparently the one which Randall 

 named agilis and was first recorded from Maine. The other, which 

 seems to be a new variety, is less common and of a general brown color 

 lacking the pale triangular space in front of the eye. Both species seem 

 to have a great diversity in size. L. agilis, although very abundant in its 

 habitat, has been little collected in Ithaca, only three specimens having 

 been recorded to the date of my first observations in the fall of 1913. It 

 is found frequently in Cascadilla Creek either on mud flats or on stone 

 ledges which border its waters. Specimens are most easily collected by 

 washing the vegetation and shore with the creek water, using the hand as 

 a dipper. "When thus disturbed, the little beetles will be noted swimming 

 speedily towards the shore and presently observed burrowing in the mud 

 or hiding in the vegetation until they are entirely concealed from view. 

 The most abundant vegetation in their environment seems to be the alga, 

 Cladophora, which is especially common in our swiftly flowing streams. 



The brown variety frequents mud holes and swampy lands but, with 

 that exception, its habits are very similar. The life history of this 

 genus is practically unworked 1 except by d'Orchymont, who gives what 

 he considers the generic larval characters of Laccobius 2 sp. ?, an immature 

 specimen of which he obtained. This is accompanied by a dorsal view 

 of the head. 



Laccobius agilis Randall 



Plate IX 



The egg-cases of the brown variety have not been taken as yet in 

 the field but those of agilis are very abundant at certain seasons of the 

 year. They have been collected in April, May, June, and July. The most 

 natural place for the cases is apparently at the water line in Cladophora 

 or attached to the roots or blades of grass. They are frequently attached 

 to the rock-ledge itself and, in such condition, are hard to remove with- 

 out breaking open the case. 



'Dr. Adam Boving, however, gave me the following data as to the rearing of Laccobius. "Dr. 

 Wesenbere-Lund has not yet published anything arbout it; Sehlick has published a note in the Danish 

 Entomologiske Meddeldser Vol. 4, 1894, p. 304 and also in a later volume, as far as I remember Vol. 6; 

 in the same periodical Vol. 5, 1895, p. 12, you will find a note that E. Rosenberg has taken and reared the 

 us larva to adult." 

 2 It differs mainly from L. agilis in that the right mandible possesses only two inner teeth. This 

 s also true of the undescribed larva of L. minutus. 



