540 



TRANS. SI . LOUIS ACAD. SCIENCE. 



the larvae of a lace-wing fly {Chrysopa)^* and a little beetle 

 Scymnus ptmctzan. 



The present season, on accounl/of the dry weather, has been 

 very favorable for the increase of the red spider ; but these three 

 insects, of which the little beetle has been the one most import- 

 ant, have kept it s j> well under control that it has done very little 

 damage. 



The larva of 6*. fuiictum was first observed on Aug. 7 on Mo- 

 rns rubra. The red spider was well distributed over the leaves 

 of this plant, but had not become so bad as to do serious damage. 

 The Scymmts increased rapidly and was soon found in all stages. 

 The mites soon began to decrease, so that on Aug. 23 none could 

 be found on the mulberry trees. On Aug. 29, neither Scymnus 

 nor mites could be found in the mulberry grove. About the same 

 state of affairs was repeated on the lindens (^Tilia^. Red spiders 

 have usually been very bad on Jlaui/iot ittilissiina and JFictis 

 Parcelli^ and attacked these plants badly early in the present 

 season. Aug. 16, J>. puiictum was found in all stages on the 

 plants, increasing so rapidly that the mites soon began to decrease 

 in numbers, and by the last of August were not numerou senough 

 to do much damage to the plants. These mites next appeared 

 on the moon-vines (^Tp07nea bona-nox) in great numbers. The 

 little beetle soon followed, and, finding such an abundance of 

 food, increased rapidly. There are now (Sept. 24th) very few 

 of the mites on these vines, and Scy/nnics is decreasing in 

 numbers. 



This Coccinellid beetle apparently goes through all of its trans- 

 formations on the plant on which its food is found, but I have not 

 found the ^g^, and hence cannot give the number of moults nor 

 the length of the larval state. In instances where I have had op- 

 portunity to observe it, the pupal state lasted four to five days. 

 I have seen a half dozen of these pupse attached to a single leaf 

 of the moon-vine. I have bred no parasites from this beetle, and 

 only in one instance have I observed any enemy to attack it ; this 



•■ I have seen one of these larvje devour no of the mites at a single meal and it was still 

 eating when I left it on account of darkness. Next day a full-grown web-worm was placed 

 in the box in which this larva was confined. The ravenous little fellow soon attacked 

 the web-worm, thrusting its long mandibles into the posterior segment of tlie web-worni, 

 which remained quiet for some time; bnt finally, bringing its head around, grasped its tor- 

 mentor by the thorax with its mandibles and crushed it to death. 



