Colorado Beetle. 89 
pass the winter in the pupal stage, which, however, is apparently 
exceptional. 
This secondary method of passing the winter makes the insect 
more difficult to cope with when it makes its appearance in a new 
country, and should be borne in mind in the destruction of any future 
colony that is found. 
The number of beetles that appeared this year (1902) was not 
large, but sufficient to show that they can well survive our winter, 
even under such unfavourable circumstances as existed on the plots 
at Tilbury. 
From specimens in the National collection it seems that there are 
three closely-related species of Doryphora, namely, D. undecemlineata , 
Stal ; D. juncta , Germ. ; and D. melanothorax, Stal. The first-named 
has black legs, but otherwise resembles the Colorado Beetle. 
I). melanothorax has an entirely dark thorax, not yellow with black 
spots and central mark, as seen in the Colorado Beetle. D. juncta , 
known as the Bogus Colorado Beetle, has two of the black lines on 
the wing cases very closely united, forming almost one broad single 
line. 
There is a fourth species in the collection, D. multitceniata, 
Stal, but there seems to be no difference between it and D. undecem- 
lineata. 
The only species likely to be confounded with the potato pest is 
D. juncta in its larval stage ; but it can easily be told when young by 
being much paler than decemlineata, and when adult by having a pale 
head instead of a black one ; its eggs also differ, being white instead 
of orange. 
The Beports sent to the Board of Agriculture on visits paid to the 
infested plots are appended. 
First Report on Colorado Beetle Outbreak at Tilbury. 
The potato plots in the allotments in Tilbury Dockyard were visited on 
August 22nd, 1901. 
The Colorado Beetle ( Doryphora 10 -lineata) was found to be present. 
The beetles were not at all numerous, not more than two dozen being 
observed. 
They were, however, very active, and breeding was going on. Larvae 
n all stages were found and three batches of ova. 
The beetles seemed to be limited to about fifty yards of the allotments, 
the end nearest the station being quite free from the pest. A single 
specimen vas also found on the Nightshade. None were detected in the 
rough herbage surrounding the plots, a likely place to harbour hibernators 
during the winter. 
The beetles showed great vitality, but the damage, although noticeable 
